Article: 222952 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Current through coils References: <122rb4p4vmdui0d@corp.supernews.com> <11783-442DB20F-474@storefull-3254.bay.webtv.net> <122rep9k2fqc49d@corp.supernews.com> <1143872213.259056.278130@z34g2000cwc.googlegroups.com> Message-ID: Date: Sat, 01 Apr 2006 12:55:44 GMT w8ji@akorn.net wrote: > He alters dimensions ... I don't remember the exact dimensions of your coil so you might refresh my memory. Was it 100 turns at 8 TPI? I have the same coil stock in a 50 uH version. As far as the EZNEC files go, I created them. Gene altered they away from the agreed upon length specifications. I altered them back and corrected a mistake I made in the traveling wave configuration. -- 73, Cecil http://www.qsl.net/w5dxp Article: 222953 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Current through coils References: <122rb4p4vmdui0d@corp.supernews.com> <11783-442DB20F-474@storefull-3254.bay.webtv.net> <122rep9k2fqc49d@corp.supernews.com> <8Niof3FsOiLEFAkM@ifwtech.co.uk> Message-ID: Date: Sat, 01 Apr 2006 13:06:00 GMT Ian White GM3SEK wrote: > It's a simplification of any real-life coil - but loading by > pure-and-simple lumped inductance is also a vital test case. It only tests the validity of the lumped-circuit model. It does NOT test the validity of the real world. Testing the validity of the real world is best left to metaphysicians, not engineers. > This form of loading is the simplest imaginable. If a theory about the > behaviour of loaded antennas fails to give correct results for this very > simplest test case, it cannot be valid... and all the further > elaborations about real-life coils will not be valid either. Whoa there, Ian. You are confusing cause and effect. If the lumped inductance fails to give correct real-world results, then it must be abandoned in favor of a more powerful model, e.g. the distributed network model. You are making my argument for me. Do you really believe a 2" dia x 12 inch coil has 100% flux linkage between coil 1 and coil 100? > But it is an absolutely basic fact that the physical world > does NOT change its behaviour according to the way we choose to think > about it. Exactly! Choosing to think about an inductance as "lumped" does NOT change the behavior of the coil. The behavior of the coil is what it is. Choosing to think about it as "lumped" is often an over-simplification, a fantasy existing only in someone's mind. > For the avoidance of doubt (as they say in Scottish legal documents): > It certainly IS possible to analyse and predict the behaviour of > coil-loaded antennas in terms of travelling and standing waves. My > objection is specifically against Cecil's method, which is provably > incorrect. The distributed network model, a superset of the lumped circuit model, is "provably incorrect" after being accepted and tested for more than a century??? By all means, please prove it incorrect. That should be very interesting - overturning a century of acceptance. -- 73, Cecil http://www.qsl.net/w5dxp Article: 222954 of rec.radio.amateur.antenna From: "John" References: Subject: Re: Elivated vertical Message-ID: Date: Sat, 1 Apr 2006 09:09:06 -0600 Thanks for the info - looks like it might be fun to try and build one... I'm sure a lot of vertical users would find something like that very handy... Kind of reminds me of the CB antennas I see with their ground plane kits except for the wire... John "Glenn" wrote in message news:aslXf.4554$C85.4317@dukeread10... > > "John" wrote in message > news:JekXf.456$8h7.50@fe04.lga... >> I've got a Butternut vertical HF6V and have plans to place it up on the >> roof. I've had it ground mounted (worked super) but due to family uses >> for the yard will have to move it up and out of the way. >> >> Rather than laying down 20 pieces of wire on my roof for radials >> (insulated with the tips protected) I'd like to try and build a Butternut >> "No radials required with the optional CPK Counterpoise kit" but I'm >> having difficulty finding the specs. >> >> Has anyone ever built one or have the measurements for a general purpose >> counterpoise kit? >> >> Thanks. >> >> John >> john_stlmo at yahoo dot com >> > > Bencher has the instructions on their site: > > > > The spreaders are 5.5' and the wire is 8'3" on a side. > Article: 222955 of rec.radio.amateur.antenna From: John - KD5YI Subject: Re: Amother look at a choke balun. References: <2ZeXf.1088$dU3.257@trnddc01> Message-ID: Date: Sat, 01 Apr 2006 15:36:49 GMT Reg Edwards wrote: >>So, then, I would have the same transformer (or balun or whatever) > > if I used > >>a wooden or plastic torus to wind the thing? >> > > ======================================== > John, yes you would. But you would not have the choke. > ---- > Reg. Reg - You removed the important part of your post. I will quote it. You said: "The presence of ferrite has hardly any effect." This is what I do not understand. If the ferrite has hardly any effect, then explain to me why plastic could not be used as long as the plastic torus is shaped the same. Now you say it wouldn't be a choke. Why not? As long as the shape of the turns of wire are the same without the ferrite, why would it not be a choke without the ferrite which has "hardly any effect"? I am not trying to pick an argument. I am trying to understand something that goes against everything I have been taught. Thanks, John Article: 222956 of rec.radio.amateur.antenna From: John - KD5YI Subject: Re: Amother look at a choke balun. References: <2ZeXf.1088$dU3.257@trnddc01> Message-ID: Date: Sat, 01 Apr 2006 15:45:48 GMT Reg Edwards wrote: > John, I'm afraid you havn't the foggiest idea about how a choke balun > works. You are being confused by the Gurus' bafflegab. I accept that statement, although I think my idea is somewhat better than a fog. I do think I understand relative permeability, for example. > A choke balun is a device which permits a balanced circuit to be > connected to an unbalanced circuit without interference to the power > flow. In this respect it is NOT a transformer. No ratios are involved. > > There are two conductors or wires in a transmission line. > > In a choke balun the two wires are TOGETHER wound round a ferrite core > AS ONE WIRE. It is this pair of wires together, as one wire, which > forms the choke using the ferrite core. But, you said, "The presence of ferrite has hardly any effect." Why are you bringing up ferrite again? Why is ferrite used if it has hardly any effect? Is there not a cheaper material? > The choke has inductance and inductive reactance. The reactance chokes > the current which would flow equally in both wires, in the same > direction in both wires. > > Entirely independently, the pair of wires can carry the normal > transmission line currents which flow in oposite directions to each > other. If normal currents in the two wires flow in opposite > directions to each other then there is no flux induced in the ferrite > and the ferrite may just as well not be there. > > So the choking action has no effect on normal transmission line > operation along the two wires. > > The choke only acts on that current which flows along the line when > both wires in parallel are considered to be ONE wire. > > For longitudinal currents the two wires can be considered as being > connected together at both ends. Connected in parallel. It's really a > single wire choke. > > It's all very simple really. There are two INDEPENDENT currents > flowing. > ---- > Reg, G4FGQ I must be more dense than I realize. I do not see an answer to my question in your reply. If your answer is there, I would appreciate it if you would point it out to me. Thanks, John Article: 222957 of rec.radio.amateur.antenna From: Gene Fuller Subject: Re: Current through coils References: <122rb4p4vmdui0d@corp.supernews.com> <11783-442DB20F-474@storefull-3254.bay.webtv.net> <122rep9k2fqc49d@corp.supernews.com> <1143872213.259056.278130@z34g2000cwc.googlegroups.com> Message-ID: <3ixXf.49763$bn3.11158@bgtnsc04-news.ops.worldnet.att.net> Date: Sat, 01 Apr 2006 15:49:19 GMT Cecil, That's quite remarkable. You issued a "challenge" to design and report on a loading coil for 4 MHz, with a whip of 8 feet. I responded with a solution that used a whip length of 10 feet. I did not "alter" anything, and I told you exactly what I did. What came back in return? Three separate times you altered my file and reported back here that something was incorrectly designed, illegal, or just plain different. You did not acknowledge the changes you made until I complained. (EZNEC did not change the coil pitch or connect the bottom of the coil to the top of the coil.) I don't have a copy of the IEEE Dictionary, but I believe the correct descriptive word for your action is dishonesty. -73 Gene W4SZ Cecil Moore wrote: > w8ji@akorn.net wrote: > >> He alters dimensions ... > > > I don't remember the exact dimensions of your coil so you > might refresh my memory. Was it 100 turns at 8 TPI? I have > the same coil stock in a 50 uH version. > > As far as the EZNEC files go, I created them. Gene altered > they away from the agreed upon length specifications. I > altered them back and corrected a mistake I made in the > traveling wave configuration. Article: 222958 of rec.radio.amateur.antenna From: richardharrison@webtv.net (Richard Harrison) Subject: Re: Current through coils Date: Sat, 1 Apr 2006 10:32:53 -0600 Message-ID: <21950-442EAB35-9@storefull-3255.bay.webtv.net> References: <122rvnrid599e3f@corp.supernews.com> Roy, W7EL wrote: "Just a couple of hours ago you said the current would have to wind its way atound each turn, following the wire from one end to the other, and it would take nearly the wire length divided by the speed of light." Yes, and I`m still convinced that is the case in an air cored r-f coil that is long because the coupling between ends of the coil isn`t enough to bypass the delay of the coil. I posted speculations on bypassing the delay in the coil. Capacitance between turns is too small over the length of the coil, said to be about one loot, and about 100 turns. Tom, W8JI had said that magnetic coupling between the start and finish of the coil bypassed the time delay of following the path of the wire. Well, nothing happens instantly when voltage is applied across a coil. 90-degrees after the voltage has crossed the zero axis on its way up, the current does the same. It lags the voltage by 90-degrees. It`s the current which induces a voltage in the coil and this is delayed by the forces predicted by Lenz`s law. 90-degrees at 4 MHz equates to about the time required for a radio wave to traverse about 60 feet of thin wire. 100 turns of wire on a 2-inch form requires about 52 feet of wire. The current travels from start to finish on the coil before the current reaches its maximum in the coil and before energy could be effectively induced from one end of the coil to the other. The wave velocity is about 984 feet per microsecond. These are just musings aloud and confirm my speculation that signal progress is through conduction on the surface of the wire of the coil. Best regards, Richard Harrison, KB5WZI Article: 222959 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Current through coils References: <122rb4p4vmdui0d@corp.supernews.com> <11783-442DB20F-474@storefull-3254.bay.webtv.net> <122rep9k2fqc49d@corp.supernews.com> <8Niof3FsOiLEFAkM@ifwtech.co.uk> <1143904124.955415.179020@i39g2000cwa.googlegroups.com> Message-ID: Date: Sat, 01 Apr 2006 18:26:25 GMT w8ji@akorn.net wrote: > It seems to me Cecil now agrees the system can be modeled as a lumped > components and loads and we do not need to use standing waves. A 100% false statement but we are accustomed to such from W8JI. Since the lumped circuit model is a subset of the distributed network model, if there is any disagreement between the two models, the distributed network model wins every time. They are both right under certain conditions and the lumped circuit model is wrong under certain conditions. Quoting from: http://www.ttr.com/corum/index.htm "There are no standing waves [allowed] on a lumped element circuit component. ... for coils whose WIRE LENGTH exceeds 1/6WL", the distributed network model is required. Quoting from: http://www.ttr.com/TELSIKS2001-MASTER-1.pdf Concerning the *impedance only* of a loading coil: "The formula will NOT (and, being lumped, can not) give the voltage magnification by VSWR dur to physically true current standing waves on the structure ... If impedance is the only item of interest, the empirical Medhurst approximation is acceptable out to about 60 degrees." But we haven't been arguing about impedance. We have been arguing about phase. Here's what the above paper says about phase shift through a loading coil. "Further, the voltage distribution passes from the loop of a sinusoid (at 90 degrees) to the linear portion of the sinusoid (for heights less than 15 degrees)." It is necessary to use the distributed network model if the phase shift through the coil is greater than 15 degrees. Continuing the quote: "Lumped elements 'have no physical dimensions and no preferred orientation in space; they can be moved around and rotated at will.' Not so for real world coils. ... The concept of coil 'self capacitance' is an attempt to circumvent transmission line effects on small coils when the current distributions begins to depart from its DC behavior." -- 73, Cecil http://www.qsl.net/w5dxp Article: 222960 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Current through coils References: <122rb4p4vmdui0d@corp.supernews.com> <11783-442DB20F-474@storefull-3254.bay.webtv.net> <122rep9k2fqc49d@corp.supernews.com> <1143872213.259056.278130@z34g2000cwc.googlegroups.com> <3ixXf.49763$bn3.11158@bgtnsc04-news.ops.worldnet.att.net> Message-ID: Date: Sat, 01 Apr 2006 18:32:12 GMT Gene Fuller wrote: > You issued a "challenge" to design and report on a loading coil for 4 > MHz, with a whip of 8 feet. I responded with a solution that used a whip > length of 10 feet. No, you didn't! You responded with a antenna length of 11.775 feet, 3.775 feet longer than the agreed upon 8 foot antenna. It wasn't the whip that was to be 8 feet, it was the entire antenna. I made that perfectly clear early on so it would match the mobile antennas in the ARRL Antenna Handbook. > You did not acknowledge the changes you made until I complained. Of course I did. Go back and read my postings about such. It wasn't until you complained that I sent you the corrected EZNEC files. I made a severe blunder in the traveling wave model and you copied my blunder. -- 73, Cecil http://www.qsl.net/w5dxp Article: 222961 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Current through coils References: <122rb4p4vmdui0d@corp.supernews.com> <11783-442DB20F-474@storefull-3254.bay.webtv.net> <122rep9k2fqc49d@corp.supernews.com> <1143872213.259056.278130@z34g2000cwc.googlegroups.com> <3ixXf.49763$bn3.11158@bgtnsc04-news.ops.worldnet.att.net> <1143908934.616412.73520@u72g2000cwu.googlegroups.com> Message-ID: Date: Sat, 01 Apr 2006 18:40:20 GMT w8ji@akorn.net wrote: > I was complaining about him altering the coil I measured and altering > the context of what I say. I was doing it from memory, Tom, which may be faulty. As I remember, you coil was 2" dia and 100 turns at 8 TPI. If that's not right, what was it? > http://www.w8ji.com/agreeing_measurements.htm > Roy's first. You're way down the list Gene. Get back in line. Telling Roy about his abortive use of standing wave current phase to try to measure phase shift when there is zero phase shift in a wire or in a coil is just stating the technical facts. As far as measuring phase through a coil goes, neither you nor W7EL has any clue as to how to make valid measurements. You guys really need to listen to Gene Fuller who said: Regarding the cos(kz)*cos(wt) term in a standing wave: > Gene Fuller, W4SZ wrote: >> In a standing wave antenna problem, such as the one you describe, there is no >> remaining phase information. Any specific phase characteristics of the traveling >> waves died out when the startup transients died out. >> >> Phase is gone. Kaput. Vanished. Cannot be recovered. Never to be seen again. >> >> The only "phase" remaining is the cos (kz) term, which is really an amplitude >> description, not a phase. The so-called "phase reversal" in longer antennas is >> not really about phase either. It is merely a representation of the periodic >> sign reversal seen in a cosine function. What is it about Gene's posting that you and W7EL don't understand? -- 73, Cecil http://www.qsl.net/w5dxp Article: 222962 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Current through coils References: <122rvnrid599e3f@corp.supernews.com> <21950-442EAB35-9@storefull-3255.bay.webtv.net> Message-ID: Date: Sat, 01 Apr 2006 18:43:42 GMT Richard Harrison wrote: > 100 turns of wire on a 2-inch form requires about 52 feet of wire. 52 feet of wire on 4 MHz is 0.21 WL. Dr. Corum says anything over 0.17 WL requires the distributed network model. The 3 nS delay measured by W8JI through that coil is simply technically impossible except in his mind. -- 73, Cecil http://www.qsl.net/w5dxp Article: 222963 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Current through coils References: <122rb4p4vmdui0d@corp.supernews.com> <11783-442DB20F-474@storefull-3254.bay.webtv.net> <1143912658.321932.277610@j33g2000cwa.googlegroups.com> Message-ID: Date: Sat, 01 Apr 2006 18:53:58 GMT K7ITM wrote: > Because of that, it is crystal-clear that that is NOT "the basic > presupposition of the lumped-circuit model." Sounds like your argument is with Dr. Corum, not with me. He said: "In fact, lumped-element circuit theory inherently employs the cosmological presupposition that the speed of light is infinite, as every EE sophmore should know. ... Lumped element representations for coils REQUIRE that the current is uniformly distributed along the coil - no wave interference and no standing waves can be present on lumped elements. ... Lumped circuit theory fails because it's a THEORY whose presuppositions are inadequate." Perhaps you missed that day in EE203? -- 73, Cecil http://www.qsl.net/w5dxp Article: 222964 of rec.radio.amateur.antenna From: richardharrison@webtv.net (Richard Harrison) Subject: Re: Current through coils Date: Sat, 1 Apr 2006 12:55:51 -0600 Message-ID: <25559-442ECCB7-613@storefull-3253.bay.webtv.net> References: Richard Clark wrote: "The apparent capacitance based on reported resonances and modeled reactance is on the order of 12 -14 pF." Have you calculated the self-capacitance of a 2in x 12in single-layer coil for yourself? The length to diameter ratio is 6. H = .92 D = 5 cm HD = 4.6 pF by the formula on page 451 of the "Radiotron Designer`s Handbook". Course, formulas are a dime a dozen and disputed. Best regards, Richard Harrison, KB5WZI Article: 222965 of rec.radio.amateur.antenna From: "Jerry" References: Subject: Re: Any recomends on a Auto tuner Message-ID: Date: Sat, 1 Apr 2006 14:07:03 -0500 "Howard W3CQH" wrote in message news:qfSdnQtbAur6ZbDZnZ2dnUVZ_sadnZ2d@adelphia.com... > Looking to purchase an auto antenna tuner that covers from approx 1.6 - > 60Mhz. Predominantly for coax. > Any suggestions? > > 73's For price and performance, it is hard to beat the LDG Pro-series. 73 Jerry > > Article: 222966 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Current through coils References: <122rb4p4vmdui0d@corp.supernews.com> <11783-442DB20F-474@storefull-3254.bay.webtv.net> <122rep9k2fqc49d@corp.supernews.com> <8Niof3FsOiLEFAkM@ifwtech.co.uk> <1143915679.346520.74580@v46g2000cwv.googlegroups.com> Message-ID: <9iAXf.61446$H71.47254@newssvr13.news.prodigy.com> Date: Sat, 01 Apr 2006 19:14:13 GMT K7ITM wrote: > YOUR model doesn't have any capacitance to the outside world, as YOU > have posted and repeated till you are perhaps blue in the face. (No > charge storage translates very directly to no capacitance, in case > anyone could have missed that.) I do wish you guys would argue in good faith. ***STRAWMAN ALERT*** I didn't say there was no capacitance to the outside world. I said such is a secondary effect, not a primary effect, and for the sake of the present argument, can be ignored as secondary effects often are ignored. > Because of that YOUR model has, guess what, ZERO time delay along the > coil. No, transmission lines have negligible capacitance to the outside world and their time delays are NOT zero. You straw man is just not believable. > It is ONLY through a combination of both inductance AND capacitance > that you get propagation velocities equal to or less than the speed of > light. Yes, and that capacitance can be either internal or external. I'm ignoring the rest of your posting because it is based on the false premises of your straw man. But you get an 'A' in Obfuscation 101. > It amazes me that you fought so hard for a distributed model in which > that capacitance to the outside world is missing, ... It is *NOT* missing. That is just your straw man. It is just secondary to the addition of the forward and reflected current phasors. At a point where the the forward and reflected current phasors add up to zero, it's hard for anything else to contribute much of an effect. -- 73, Cecil http://www.qsl.net/w5dxp Article: 222967 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Current through coils References: <122rb4p4vmdui0d@corp.supernews.com> <11783-442DB20F-474@storefull-3254.bay.webtv.net> <1143912658.321932.277610@j33g2000cwa.googlegroups.com> <1143918684.221674.276010@i39g2000cwa.googlegroups.com> Message-ID: Date: Sat, 01 Apr 2006 19:26:42 GMT K7ITM wrote: > I REGULARLY model transmission lines as "lumped elements" and do NOT > "presuppose that the speed of light" through them is infinite. I'm interested in knowing how you model a shorted quarter wavelength stub using the lumped element model. > I REGULARLY model op amps as "lumped elements" and do NOT presuppose > that the phase shift (and therefore propagation time) through them is > infinite. I should hope not! You would never get a signal through them. :-) > I REGULARLY model inductors as "lumped elements", and do not presuppose > that they have no resistances and capacitances parasitic to their > inductANCE. Then you are somehow applying a patch to the lumped element model. The basic lumped element model assumes no resistance and no capacitance. That's how the lumped inductance-only works in EZNEC. > I find that my models very reliably predict the behaviour I actually > observe in the circuits I build. I am served very well by the models I > use. Do you use them on 75m bugcatcher coils and obtain an incorrect phase shift as W8JI and W7EL have done? > By the way, what's EE203? The sophmore EE class alluded to by Dr. Corum. -- 73, Cecil http://www.qsl.net/w5dxp Article: 222968 of rec.radio.amateur.antenna From: "Jim" References: <1143759372.007217.65370@g10g2000cwb.googlegroups.com> Subject: Re: Adjusting a colinear antenna Message-ID: <4HAXf.10092$dU3.6515@trnddc01> Date: Sat, 01 Apr 2006 19:40:48 GMT I saw a construction article in the ARRL Antenna Handbook , 13th Edition, 1980 on page 247-249. I also did some google searchs and there was a thesis paper on this very same article in the 1990's where two people modeled the antenna described in the Antenna Handbook and said there were errors in the article. I could not get the complete paper that would have gone into the details. I have built one of these antennas for the 850 mHz range using rigid coax per the article in the ARRL Handbook (with 7 half wave elements, and two 1/4 wave elements per the article) and saw poorer performance compared to a small 1/4 whip antenna connnected to the back of the radio. Not sure what went wrong. Comments?? Tnx Jim "K7ITM" wrote in message news:1143759372.007217.65370@g10g2000cwb.googlegroups.com... > Measure the velocity factor (at or near the operating frequency)! If > you are using solid polyethylene dielectric cable, then the v.f. really > should be close to 0.66. For a flat pattern, you want the > center-to-center spacing of the elements to be 1/2 wave, considering > the net velocity factor. I say net because at the junctions between > elements, it's possible that the effective v.f. is slightly higher than > in the coax itself. You'd cut the elements long by enough to let you > solder them together and end up with that 1/2 wave center to center. > (It's easier and equivalent to measure from top of one element to the > top of the next element, etc.) > > Since the _pattern_ depends mainly on the phasing of the feed system, > and the phasing is established mainly by the propagation velocity in > the line, and not by the surrounding environment, putting it next to > something won't affect the pattern, except that if there are conductors > in that display you want to mount it to, they may very well screw up > the pattern by allowing current where you don't want it. Especially if > there is some piece that's resonant near the operating frequency it > would be like putting an unwanted parasitic element in a Yagi: not a > good idea for optimum performance. > > OK, so the phasing is designed to get you the right pattern. But the > phasing is independent of the feedpoint impedance. You need to match > to that, and you also need to decouple the antenna from nearby > conductors. Any conductors in the display fall into that category, but > the feedline from the xcvr also does. A choke balun, and other > feedline choking, is very highly recommended. > > I used to have a web page with quite a bit of text about the why and > the how of coaxial collinears; it wasn't a construction article, but it > armed you with enough info that you could go out and make one that > would work well on pretty much any frequency you might want. It > included things like why the center-center half wave spacing, and why > it's slightly better to use foam dielectric cable. If I got enough > requests, I'd make a revised version of that available, maybe even with > some pictures this time. Every once in a while I get a request to > re-print it in a club newsletter, so I know there are some of those > floating around out there. > > Cheers, > Tom > Article: 222969 of rec.radio.amateur.antenna From: "Tom Donaly" Subject: Re: Current through coils References: <122rb4p4vmdui0d@corp.supernews.com> <11783-442DB20F-474@storefull-3254.bay.webtv.net> <1143912658.321932.277610@j33g2000cwa.googlegroups.com> <1143918684.221674.276010@i39g2000cwa.googlegroups.com> Message-ID: Date: Sat, 01 Apr 2006 20:57:00 GMT Cecil Moore wrote: > K7ITM wrote: > >> I REGULARLY model transmission lines as "lumped elements" and do NOT >> "presuppose that the speed of light" through them is infinite. > > > I'm interested in knowing how you model a shorted quarter wavelength > stub using the lumped element model. > >> I REGULARLY model op amps as "lumped elements" and do NOT presuppose >> that the phase shift (and therefore propagation time) through them is >> infinite. > > > I should hope not! You would never get a signal through them. :-) > >> I REGULARLY model inductors as "lumped elements", and do not presuppose >> that they have no resistances and capacitances parasitic to their >> inductANCE. > > > Then you are somehow applying a patch to the lumped element model. > The basic lumped element model assumes no resistance and no > capacitance. That's how the lumped inductance-only works in EZNEC. > >> I find that my models very reliably predict the behaviour I actually >> observe in the circuits I build. I am served very well by the models I >> use. > > > Do you use them on 75m bugcatcher coils and obtain an incorrect > phase shift as W8JI and W7EL have done? > >> By the way, what's EE203? > > > The sophmore EE class alluded to by Dr. Corum. Cecil, there are two Corums and they're both Tesla coil crackpots. Secondly, Tom is right, you have to have capacitance to somewhere or your transmission line analogy becomes mired in absurdities. Third, it isn't enough to think something up in your head to make a convincing theory, you have to be able to predict behavior with it. Finally, you have to understand your subject before you even start thinking. I'm surprised you didn't even take the time to make a real coil and at least try to determine its characteristics before wasting everyone's time by starting this thread. 73, Tom Donaly, KA6RUH Article: 222970 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Current through coils References: <122rb4p4vmdui0d@corp.supernews.com> <11783-442DB20F-474@storefull-3254.bay.webtv.net> <1143912658.321932.277610@j33g2000cwa.googlegroups.com> <1143918684.221674.276010@i39g2000cwa.googlegroups.com> Message-ID: <4GCXf.63456$Jd.43417@newssvr25.news.prodigy.net> Date: Sat, 01 Apr 2006 21:56:16 GMT Tom Donaly wrote: > Cecil, there are two Corums and they're both Tesla coil > crackpots. Secondly, Tom is right, you have to have capacitance > to somewhere or your transmission line analogy becomes mired in > absurdities. Would you guys please stop implying falsehoods and make an attempt to argue in good faith? I didn't say the capacitance didn't exist. I said it was a secondary effect to the superposition of the forward and reflected waves. That you are forced to twist what I said speaks volumes about your argument. Why don't you feel secure enough in your technical argument not to have to twist my words into something I didn't say? > Third, it isn't enough to think something up in > your head to make a convincing theory, you have to be able to > predict behavior with it. I have predicted behavior on http://www.qsl.net/w5dxp/current.htm with text surrounding http://www.qsl.net/w5dxp/1WLDIP.GIF. That graphic is not disembodied as you claimed. It is surrounded with examples and text, more than enough proof for any rational person. The current at each end of a coil obviously depends upon where it is installed in the standing wave antenna system. Your wearing of blinders doesn't hide that technical fact from anyone except yourself. -- 73, Cecil http://www.qsl.net/w5dxp Article: 222971 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Current through coils References: <122rb4p4vmdui0d@corp.supernews.com> <11783-442DB20F-474@storefull-3254.bay.webtv.net> <1143912658.321932.277610@j33g2000cwa.googlegroups.com> <1143918684.221674.276010@i39g2000cwa.googlegroups.com> Message-ID: Date: Sat, 01 Apr 2006 22:00:49 GMT Richard Clark wrote: > All measurements done by everyone are incorrect. > > Yours, by your own admission 59% in error, ... Uhhhh Richard, those weren't measurements. Those were calculated results, using formulas out of books. The only measurements that I have made were of 1. self-resonant frequencies within the accuracy of an MFJ-259B and 2. standing wave phase measurements that agree with Kraus and EZNEC. The 59% accuracy was in my wild ass *guesses* as opposed to the 207% error in W8JI's phase *measurements*. -- 73, Cecil http://www.qsl.net/w5dxp Article: 222972 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Current through coils References: <122rb4p4vmdui0d@corp.supernews.com> <11783-442DB20F-474@storefull-3254.bay.webtv.net> <122rep9k2fqc49d@corp.supernews.com> <1143872213.259056.278130@z34g2000cwc.googlegroups.com> <3ixXf.49763$bn3.11158@bgtnsc04-news.ops.worldnet.att.net> <1143908934.616412.73520@u72g2000cwu.googlegroups.com> Message-ID: Date: Sat, 01 Apr 2006 22:07:29 GMT w8ji@akorn.net wrote: > I was complaining about him altering the coil I measured and altering > the context of what I say. The real problem is your concept that "current is current", implying that there is some sort of identity between all kinds of current. Is DC current identical to RF current? If not, your "current is current" statement is incorrect. There are different flavors of current. DC Vs RF is just one. Standing wave current Vs traveling wave current is another. That you don't see the difference between func(kx)*func(wt) and func(kx +/- wt) is the entire problem. Why are you so unwilling to discuss that narrow technical topic? If you would discuss that problem, you might wind up winning the rest of the argument but you will never know until you do. -- 73, Cecil http://www.qsl.net/w5dxp Article: 222973 of rec.radio.amateur.antenna From: John - KD5YI Subject: Re: Amother look at a choke balun. References: <2ZeXf.1088$dU3.257@trnddc01> <0mct22dtjmgg0rkrr16f16ukbjdtrgntfk@4ax.com> Message-ID: Date: Sat, 01 Apr 2006 22:13:05 GMT Richard Clark wrote: > On Sat, 01 Apr 2006 15:45:48 GMT, John - KD5YI > wrote: > > >>Reg Edwards wrote: >> >>>John, I'm afraid you havn't the foggiest idea about how a choke balun >>>works. You are being confused by the Gurus' bafflegab. > > ... > >>I must be more dense than I realize. I do not see an answer to my question >>in your reply. If your answer is there, I would appreciate it if you would >>point it out to me. > > > Hi John, > > No, you are no more dense than the next, and Reggie's bafflegab is no > more distinct than all that which preceded it - once you discard his > pretension. Hi, Richard - I am afraid I do not understand the meaning of "bafflegab". I take it to be a derogatory term indicating that the posting person believes the monologue to be unbelievable. Or something like that. Wikipedia has nothing on the meaning of this word. A search of Dictionary.com produces Gobbledygook which is no help at all. Another search on Dictionary.com of Gobbledygook results in "Unclear, wordy jargon." Is this what is meant? Thanks, John Article: 222974 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Amother look at a choke balun. References: <2ZeXf.1088$dU3.257@trnddc01> <0mct22dtjmgg0rkrr16f16ukbjdtrgntfk@4ax.com> Message-ID: Date: Sat, 01 Apr 2006 22:15:35 GMT John - KD5YI wrote: > I am afraid I do not understand the meaning of "bafflegab". A Netscape web search turned up 4890 hits. -- 73, Cecil http://www.qsl.net/w5dxp Article: 222975 of rec.radio.amateur.antenna From: Alan WA4SCA Subject: Re: Any recomends on a Auto tuner Message-ID: References: Date: Sat, 01 Apr 2006 22:53:09 GMT The LDG tuners are certainly durable. I still use an old AT-11, no longer made, which just keeps on matching everything I throw at it. After a while, you don't even notice the "marbles in a Waring blender sound" when the relays tune. Hi Hi! -- Alan WA4SCA Article: 222976 of rec.radio.amateur.antenna From: Jim - NN7K Subject: Re: Adjusting a colinear antenna References: <1143759372.007217.65370@g10g2000cwb.googlegroups.com> <4HAXf.10092$dU3.6515@trnddc01> Message-ID: Date: Sat, 01 Apr 2006 23:24:11 GMT Also, consider that this is a GAIN antenna (a misnomer, as the "gain" is created, by takeing power from somewhere else!). This means that the radiation patern is on the horizon, tho, say 15 degrees above, or below THAT horizon, the radiation from that "gain antenna" may be a LOSS! and it gets worse, at higher angles! Kinda like aiming a yagi at a (say , 20 degree angle above (or below) the horizon, wouldn't expect to have a full signal, if the SOURCE were on the horizon, would you)? A 1/4 wave whip is much more forgiveing at higher angles of radiation0, while your "GAIN" antenna has a pattern like a doughnut (power concentrated on the horizon, limited radiation at angles above, and below that horizon). This can be a problem in mountainous territory,where a 1/4 wave whip will out-perform a gain antenna for coverage. As info, Jim NN7K Jim wrote: > I saw a construction article in the ARRL Antenna Handbook , 13th Edition, > 1980 on page 247-249. I also did some google searchs and there was a thesis > paper on this very same article in the 1990's where two people modeled the > antenna described in the Antenna Handbook and said there were errors in the > article. I could not get the complete paper that would have gone into the > details. > > I have built one of these antennas for the 850 mHz range using rigid coax > per the article in the ARRL Handbook (with 7 half wave elements, and two 1/4 > wave elements per the article) and saw poorer performance compared to a > small 1/4 whip antenna connnected to the back of the radio. Not sure what > went wrong. > > Comments?? > > Tnx > > Jim > "K7ITM" wrote in message > news:1143759372.007217.65370@g10g2000cwb.googlegroups.com... > >>Measure the velocity factor (at or near the operating frequency)! If >>you are using solid polyethylene dielectric cable, then the v.f. really >>should be close to 0.66. For a flat pattern, you want the >>center-to-center spacing of the elements to be 1/2 wave, considering >>the net velocity factor. I say net because at the junctions between >>elements, it's possible that the effective v.f. is slightly higher than >>in the coax itself. You'd cut the elements long by enough to let you >>solder them together and end up with that 1/2 wave center to center. >>(It's easier and equivalent to measure from top of one element to the >>top of the next element, etc.) >> >>Since the _pattern_ depends mainly on the phasing of the feed system, >>and the phasing is established mainly by the propagation velocity in >>the line, and not by the surrounding environment, putting it next to >>something won't affect the pattern, except that if there are conductors >>in that display you want to mount it to, they may very well screw up >>the pattern by allowing current where you don't want it. Especially if >>there is some piece that's resonant near the operating frequency it >>would be like putting an unwanted parasitic element in a Yagi: not a >>good idea for optimum performance. >> >>OK, so the phasing is designed to get you the right pattern. But the >>phasing is independent of the feedpoint impedance. You need to match >>to that, and you also need to decouple the antenna from nearby >>conductors. Any conductors in the display fall into that category, but >>the feedline from the xcvr also does. A choke balun, and other >>feedline choking, is very highly recommended. >> >>I used to have a web page with quite a bit of text about the why and >>the how of coaxial collinears; it wasn't a construction article, but it >>armed you with enough info that you could go out and make one that >>would work well on pretty much any frequency you might want. It >>included things like why the center-center half wave spacing, and why >>it's slightly better to use foam dielectric cable. If I got enough >>requests, I'd make a revised version of that available, maybe even with >>some pictures this time. Every once in a while I get a request to >>re-print it in a club newsletter, so I know there are some of those >>floating around out there. >> >>Cheers, >>Tom >> > > > Article: 222977 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Current through coils References: <122rb4p4vmdui0d@corp.supernews.com> <11783-442DB20F-474@storefull-3254.bay.webtv.net> <1143912658.321932.277610@j33g2000cwa.googlegroups.com> <1143918684.221674.276010@i39g2000cwa.googlegroups.com> <9kut229k8f75p8ins72dkivoltj9rtqaod@4ax.com> Message-ID: Date: Sat, 01 Apr 2006 23:36:15 GMT Richard Clark wrote: > Have you been sleeping with Kraus again? Yes, I often sleep with Kraus and Balanis. You should try occasionally reading a reference book instead of watching The Three Stogies. :-) -- 73, Cecil http://www.qsl.net/w5dxp Article: 222978 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Amother look at a choke balun. References: <2ZeXf.1088$dU3.257@trnddc01> <0mct22dtjmgg0rkrr16f16ukbjdtrgntfk@4ax.com> <9tvt22l88ibl2lp37o1tgbg4trohq9mldh@4ax.com> Message-ID: <7dEXf.50613$2O6.23956@newssvr12.news.prodigy.com> Date: Sat, 01 Apr 2006 23:41:55 GMT Richard Clark wrote: > John - KD5YI wrote: >>I am afraid I do not understand the meaning of "bafflegab". > > It is a term of invention by the greatest practitioner of that art - > Reggie, of course! Sorry, Reg didn't invent the word. It's been around for more than half a century. "Bafflegab - This word hit the newspapers and public notice on 19 January 1952, the day after a plaque was presented to its inventor to mark his creation of this invaluable word. He was Milton A Smith, assistant general counsel for the US Chamber of Commerce." -- 73, Cecil http://www.qsl.net/w5dxp Article: 222979 of rec.radio.amateur.antenna From: John - KD5YI Subject: Re: Amother look at a choke balun. References: <2ZeXf.1088$dU3.257@trnddc01> <0mct22dtjmgg0rkrr16f16ukbjdtrgntfk@4ax.com> <9tvt22l88ibl2lp37o1tgbg4trohq9mldh@4ax.com> Message-ID: Date: Sat, 01 Apr 2006 23:42:04 GMT Richard Clark wrote: > On Sat, 01 Apr 2006 22:13:05 GMT, John - KD5YI > wrote: > > >>I am afraid I do not understand the meaning of "bafflegab". > > > Hi John, > > It is a term of invention by the greatest practitioner of that art - > Reggie, of course! He introduces nearly every example of it with the > term nestled in his post like a road side flare. Bafflegab is what > was written before you (the second poster to answer) got your say in. > > There are similar usage examples of his with "gurus," a term that was > not coined by him, but similarly littered in postings for effect in > his (and imitators') attempts in social climbing. "Gurus" are those > who got to say it first. > > So, in the pecking order of it all, "gurus" write "bafflegab" - > unless, of course, you posted first. As a strategic variation on this > theme, there is the inverted-guru-gambit that is something like en > passant. That is, you don't post an answer even if you do manage to > be first, you post how it will be answered wrong by others who you > claim to be gurus. > > Reggie has been most influential in these stylistic touches and more > than a few correspondents ape his method. Unfortunately, this also > reveals how quickly novelty descends into cliché; and how wikipedia > trails in social currency. > > 73's > Richard Clark, KB7QHC Richard - I must say that the meaning is no clearer to me now. Your explanation makes no sense to me. I apologize for my lack of understanding. Thanks for trying to explain nevertheless. Cheers, John Article: 222980 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Amother look at a choke balun. References: <2ZeXf.1088$dU3.257@trnddc01> <0mct22dtjmgg0rkrr16f16ukbjdtrgntfk@4ax.com> <9tvt22l88ibl2lp37o1tgbg4trohq9mldh@4ax.com> Message-ID: Date: Sat, 01 Apr 2006 23:44:51 GMT John - KD5YI wrote: > I must say that the meaning is no clearer to me now. Your explanation > makes no sense to me. I apologize for my lack of understanding. Synonym is "Gobblydegook". Does that help? -- 73, Cecil http://www.qsl.net/w5dxp Article: 222981 of rec.radio.amateur.antenna From: ml Subject: Re: Any recomends on a Auto tuner References: <1143906989.915252.172060@z34g2000cwc.googlegroups.com> Message-ID: Date: Sat, 01 Apr 2006 23:47:06 GMT In article <1143906989.915252.172060@z34g2000cwc.googlegroups.com>, "KG0WX" wrote: > Depends on how bad a mismatch and how much RF you're > going to cram through it. For easier setups, like a dipole and > 100w, A LDG Z100 will work. Need more? Get an LDG AT200Pro > or 100 pro. If you are QRP, try a Z11, also from LDG. > > I've had experience with all the above tuners (except the 200 which > UPS left on my porch then got stolen.) Anyways, LDG makes > a fair to excellent product line HOWEVER, My K2's internal tuner > will tune a worse match than any of the listed LDG tuners. Of course > if you want a KAT2 tuner, You'll need a K2 to install it in.... > > I know - you were just looking for an excuse to build a K2, right? > > Ken KG0WX surprized that nobody mentioned the sgc tungers i've been using 2 for quite some time the mac200 and a sgc237 it tunes all bands/modes a tiny short dipole that i am using down to never more than 1.2swr tunes in a sec or so and well the 237 is mostly quite, but being roof mounted moot point the mac200 has usual relay noise on initial tune, brief click after but has way cool 4way antenna switch and swr /pwr meters!! and they tune w/rf by themselfs not that it's unique i also use ldg great stuff these 2 firms seem to kinda corner the market Article: 222982 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Any recomends on a Auto tuner References: <1143906989.915252.172060@z34g2000cwc.googlegroups.com> Message-ID: Date: Sat, 01 Apr 2006 23:50:14 GMT ml wrote: > surprized that nobody mentioned the sgc tungers My SGC-230 will tune everything including no antenna at all. I once forgot to install the coil and stinger on my mobile antenna. The SGC-230 faithfully tuned the three foot bottom section to resonance on 75m. :-) -- 73, Cecil http://www.qsl.net/w5dxp Article: 222983 of rec.radio.amateur.antenna From: John - KD5YI Subject: Re: Amother look at a choke balun. References: <2ZeXf.1088$dU3.257@trnddc01> <0mct22dtjmgg0rkrr16f16ukbjdtrgntfk@4ax.com> <9tvt22l88ibl2lp37o1tgbg4trohq9mldh@4ax.com> Message-ID: Date: Sat, 01 Apr 2006 23:55:15 GMT Dan Richardson adelphia wrote: > On Sat, 01 Apr 2006 23:42:04 GMT, John - KD5YI > wrote: > > >>Richard - >> >>I must say that the meaning is no clearer to me now. Your explanation makes >>no sense to me. I apologize for my lack of understanding. >> >>Thanks for trying to explain nevertheless. >> >>Cheers, >>John > > > How about "doubletalk"? > > That comes pretty close. > > Regards, > Danny, K6MHE Thanks, Danny. John Article: 222984 of rec.radio.amateur.antenna From: "David G. Nagel" Subject: Re: Amother look at a choke balun. Date: Sat, 01 Apr 2006 18:18:51 -0600 Message-ID: <122u63mbiu4b725@corp.supernews.com> References: <2ZeXf.1088$dU3.257@trnddc01> <0mct22dtjmgg0rkrr16f16ukbjdtrgntfk@4ax.com> <9tvt22l88ibl2lp37o1tgbg4trohq9mldh@4ax.com> John - KD5YI wrote: > Richard Clark wrote: > >> On Sat, 01 Apr 2006 22:13:05 GMT, John - KD5YI >> wrote: >> >> >>> I am afraid I do not understand the meaning of "bafflegab". >> >> >> >> Hi John, >> >> It is a term of invention by the greatest practitioner of that art - >> Reggie, of course! He introduces nearly every example of it with the >> term nestled in his post like a road side flare. Bafflegab is what >> was written before you (the second poster to answer) got your say in. >> >> There are similar usage examples of his with "gurus," a term that was >> not coined by him, but similarly littered in postings for effect in >> his (and imitators') attempts in social climbing. "Gurus" are those >> who got to say it first. >> >> So, in the pecking order of it all, "gurus" write "bafflegab" - >> unless, of course, you posted first. As a strategic variation on this >> theme, there is the inverted-guru-gambit that is something like en >> passant. That is, you don't post an answer even if you do manage to >> be first, you post how it will be answered wrong by others who you >> claim to be gurus. >> >> Reggie has been most influential in these stylistic touches and more >> than a few correspondents ape his method. Unfortunately, this also >> reveals how quickly novelty descends into cliché; and how wikipedia >> trails in social currency. >> >> 73's >> Richard Clark, KB7QHC > > > > Richard - > > I must say that the meaning is no clearer to me now. Your explanation > makes no sense to me. I apologize for my lack of understanding. > > Thanks for trying to explain nevertheless. > > Cheers, > John John; The term has been used in the TV program from the 70's "Battlestar Galactica". It means spouting "BULLSHIT". Dave N Article: 222985 of rec.radio.amateur.antenna From: "David G. Nagel" Subject: Re: paint antenna? Date: Sat, 01 Apr 2006 18:22:30 -0600 Message-ID: <122u6ah1aa5iv2e@corp.supernews.com> References: ml wrote: > just read a article someplace about a new conductive paint that is going > to be used by different sources (pvt/mil) to in effect paint an antenna > on a surface. once such use was an 'orbiting' blimp , planes etc to > repete signals > > > ok so i wonder my roof has a flat brick wall it's 40ft tall 40ft wide > > if i painted a antenna design think i'd get any useful performance in at > least one direction? > > unf it didn't state any spec's but it's commercial > > > just really thinking out louad how a antenna w/little profile but > otherwise large surfacce area might work Actually if the paint is continuous in it's conductivity there is no reason why a painted antenna picture would not work. Tuning it might be problematic but would work. Try it and report back. Dave WD9BDZ Article: 222986 of rec.radio.amateur.antenna From: Roy Lewallen Subject: Re: Balloon lifted wire antenna? Date: Sat, 01 Apr 2006 18:22:12 -0800 Message-ID: <122udalh0vekk4e@corp.supernews.com> References: <220320061901558586%artie.m@gNOSPAMmail.com> <4429e44e$0$7326$39cecf19@news.twtelecom.net> <442B3A23.2030505@fuse.net> <122mg7elcu3fub4@corp.supernews.com> According to http://www.llnl.gov/es_and_h/hsm/doc_18.04/doc18-04.html, the flammability range of hydrogen is 4 - 75% by volume in air. But that's still a wide range, much more than I incorrectly implied. Thanks for the correction. Roy Lewallen, W7EL Jim Higgins wrote: > On Wed, 29 Mar 2006 18:22:37 -0800, Roy Lewallen > wrote: > > >> Hydrogen is explosive only in the correct, fairly narrow, range of >> mixtures with oxygen. > > That "fairly narrow" explosive range would be from about 15% - 90% by > volume in oxygen. For flammability (including explosion), the range > is about 5% - 94% by volume. > > In air the ranges are about 18% - 59% for explosion and about 4% - 74% > for flammability - including explosion. > > >> A big bag of hydrogen won't explode. It'll burn >> only at the outside edges where it's mixing with oxygen. It'll rapidly >> disperse to a point where it's too lean a mixture to burn, so I believe >> there's only a fairly narrow physical region around a blob of pure >> hydrogen where it's flammable. > > > Bear in mind that "too lean" is under 5% in pure oxygen or in air. > > >> Hydrogen stopped being used for dirigibles more >> because of the danger perceived by the public >> after seeing the Hindenburg than by real danger. > > > I'm not getting into that debate as there seem to be as many different > versions of the facts as there are theories needing facts to support > them. > > If you want to read some really bad science, keep abreast of the > developing lobby touting a "Hydrogen Economy." Article: 222987 of rec.radio.amateur.antenna From: "Jerry" References: Subject: Re: Any recomends on a Auto tuner Message-ID: Date: Sat, 1 Apr 2006 22:02:46 -0500 "Alan WA4SCA" wrote in message news:ut0u22du7uehlk1dtq0hu79vn6eid9n8u8@4ax.com... > The LDG tuners are certainly durable. I still use an old AT-11, no > longer made, which just keeps on matching everything I throw at it. > After a while, you don't even notice the "marbles in a Waring blender > sound" when the relays tune. Hi Hi! > > > -- > Alan > WA4SCA I have the Pro100 and it will try to tune up a garage door! There are few things it won't try to tune. I have the Cobra Ultralite Senior antenna and I really enjoy the ability to go from 160-10 Meters with one wire antenna. 73 Jerry K4KWH Article: 222988 of rec.radio.amateur.antenna Date: Sat, 01 Apr 2006 21:39:41 -0600 From: Tom Ring Subject: Re: Current through coils References: <122rb4p4vmdui0d@corp.supernews.com> <11783-442DB20F-474@storefull-3254.bay.webtv.net> <1143912658.321932.277610@j33g2000cwa.googlegroups.com> <1143918684.221674.276010@i39g2000cwa.googlegroups.com> Message-ID: <442f477d$0$7329$39cecf19@news.twtelecom.net> Tom Donaly wrote: > > > Cecil, there are two Corums and they're both Tesla coil > crackpots. Secondly, Tom is right, you have to have capacitance > to somewhere or your transmission line analogy becomes mired in > absurdities. Third, it isn't enough to think something up in > your head to make a convincing theory, you have to be able to > predict behavior with it. Finally, you have to understand your > subject before you even start thinking. I'm surprised you didn't > even take the time to make a real coil and at least try to > determine its characteristics before wasting everyone's > time by starting this thread. > 73, > Tom Donaly, KA6RUH Tom, You, and everyone else is, as we put it in the midwest, and probably elsewhere, "pissing into the wind". You cannot win an argument with someone that does not acknowledge reality. tom K0TAR Article: 222989 of rec.radio.amateur.antenna From: "jimmiefender@bellsouth.net" References: <1143908604.326393.313760@j33g2000cwa.googlegroups.com> Subject: Re: What is an EH antenna Message-ID: Date: Sat, 1 Apr 2006 22:55:43 -0500 "Richard Clark" wrote in message news:indt22h9510krnopa8m4n1sthokogfllvr@4ax.com... > On 1 Apr 2006 08:23:24 -0800, "JIMMIE" wrote: > >>Would it be >>appropriate to say that an EH antenna is more like a coupler that >>utilises the antenna support structure(tower/mast) and feedline as the >>radiating elements of the antenna?. > > Hi Jimmie, > > Sounds fair. You may be disappointed with such a short answer. So if > you simply search Google groups using EH antenna as key terms, you > will find more discussion, but it will all reduce to your short > observation above. > > 73's > Richard Clark, KB7QHC I would suppose that under the right conditions an antenna like this could perform reasonably well if it were properly set up and I can see how getting consistent results would be difficult. This would leave some people to swear by it while other swear at it. Article: 222990 of rec.radio.amateur.antenna From: "Jim" References: <1143759372.007217.65370@g10g2000cwb.googlegroups.com> <4HAXf.10092$dU3.6515@trnddc01> Subject: Re: Adjusting a colinear antenna Message-ID: Date: Sun, 02 Apr 2006 04:43:51 GMT Jim, Thanks for info. You are correct as I do live in "hilly" area. I raised the antenna up to 30 feet and there was a big difference in signal strength. I do not have equiment to measure the difference accurately, but on an Icom R-7000 there was 1 s unit (or so) difference but there was much lower noise and better readability. Thanks again Jim "Jim - NN7K" wrote in message news:vYDXf.63484$Jd.41941@newssvr25.news.prodigy.net... > Also, consider that this is a GAIN antenna (a misnomer, as the "gain" > is created, by takeing power from somewhere else!). This means that the > radiation patern is on the horizon, tho, say 15 degrees above, or below > THAT horizon, the radiation from that "gain antenna" may be a LOSS! and > it gets worse, at higher angles! Kinda like aiming a yagi at a (say , 20 > degree angle above (or below) the horizon, wouldn't expect to have a > full signal, if the SOURCE were on the horizon, would you)? A 1/4 wave > whip is much more forgiveing at higher angles of radiation0, while your > "GAIN" antenna has a pattern like a doughnut (power concentrated on > the horizon, limited radiation at angles above, and below that horizon). > This can be a problem in mountainous territory,where a 1/4 wave whip > will out-perform a gain antenna for coverage. As info, Jim NN7K > > > Jim wrote: >> I saw a construction article in the ARRL Antenna Handbook , 13th Edition, >> 1980 on page 247-249. I also did some google searchs and there was a >> thesis paper on this very same article in the 1990's where two people >> modeled the antenna described in the Antenna Handbook and said there were >> errors in the article. I could not get the complete paper that would >> have gone into the details. >> >> I have built one of these antennas for the 850 mHz range using rigid coax >> per the article in the ARRL Handbook (with 7 half wave elements, and two >> 1/4 wave elements per the article) and saw poorer performance compared to >> a small 1/4 whip antenna connnected to the back of the radio. Not sure >> what went wrong. >> >> Comments?? >> >> Tnx >> >> Jim >> "K7ITM" wrote in message >> news:1143759372.007217.65370@g10g2000cwb.googlegroups.com... >> >>>Measure the velocity factor (at or near the operating frequency)! If >>>you are using solid polyethylene dielectric cable, then the v.f. really >>>should be close to 0.66. For a flat pattern, you want the >>>center-to-center spacing of the elements to be 1/2 wave, considering >>>the net velocity factor. I say net because at the junctions between >>>elements, it's possible that the effective v.f. is slightly higher than >>>in the coax itself. You'd cut the elements long by enough to let you >>>solder them together and end up with that 1/2 wave center to center. >>>(It's easier and equivalent to measure from top of one element to the >>>top of the next element, etc.) >>> >>>Since the _pattern_ depends mainly on the phasing of the feed system, >>>and the phasing is established mainly by the propagation velocity in >>>the line, and not by the surrounding environment, putting it next to >>>something won't affect the pattern, except that if there are conductors >>>in that display you want to mount it to, they may very well screw up >>>the pattern by allowing current where you don't want it. Especially if >>>there is some piece that's resonant near the operating frequency it >>>would be like putting an unwanted parasitic element in a Yagi: not a >>>good idea for optimum performance. >>> >>>OK, so the phasing is designed to get you the right pattern. But the >>>phasing is independent of the feedpoint impedance. You need to match >>>to that, and you also need to decouple the antenna from nearby >>>conductors. Any conductors in the display fall into that category, but >>>the feedline from the xcvr also does. A choke balun, and other >>>feedline choking, is very highly recommended. >>> >>>I used to have a web page with quite a bit of text about the why and >>>the how of coaxial collinears; it wasn't a construction article, but it >>>armed you with enough info that you could go out and make one that >>>would work well on pretty much any frequency you might want. It >>>included things like why the center-center half wave spacing, and why >>>it's slightly better to use foam dielectric cable. If I got enough >>>requests, I'd make a revised version of that available, maybe even with >>>some pictures this time. Every once in a while I get a request to >>>re-print it in a club newsletter, so I know there are some of those >>>floating around out there. >>> >>>Cheers, >>>Tom >>> >> >> Article: 222991 of rec.radio.amateur.antenna From: "Jim" References: <1143759372.007217.65370@g10g2000cwb.googlegroups.com> <4HAXf.10092$dU3.6515@trnddc01> Subject: Re: Adjusting a colinear antenna Message-ID: <7GIXf.1633$Py4.193@trnddc06> Date: Sun, 02 Apr 2006 04:45:55 GMT Jerry, Thanks for input. I agree, the effort of using rigid coax and putting it all together (without equipment to measure accurately) is an investment in time. Jim "Jerry Martes" wrote in message news:QuEXf.5165$Up2.1408@trnddc07... > > "Jim" wrote in message > news:4HAXf.10092$dU3.6515@trnddc01... >>I saw a construction article in the ARRL Antenna Handbook , 13th Edition, >>1980 on page 247-249. I also did some google searchs and there was a >>thesis paper on this very same article in the 1990's where two people >>modeled the antenna described in the Antenna Handbook and said there were >>errors in the article. I could not get the complete paper that would have >>gone into the details. >> >> I have built one of these antennas for the 850 mHz range using rigid coax >> per the article in the ARRL Handbook (with 7 half wave elements, and two >> 1/4 wave elements per the article) and saw poorer performance compared to >> a small 1/4 whip antenna connnected to the back of the radio. Not sure >> what went wrong. >> >> Comments?? >> >> Tnx >> >> Jim >> "K7ITM" wrote in message > > Hi Jim > > A properly done colinear array of 8 half wave elements will sure have a > highly directive pattern in the Elevation plane. With some luck and low > loss components you might get 8 or 9 dBi. But, the pattern will have a > pattern max thats broadside to the axis of the colinear array at only one > frequency. That pattern max will squint up and down (with respect to the > horizon) as the frequency varies from that center frequency. > I'd bet that you will be able to realize appreciable dirrectivity from an > array of 7 lengths of RG-6 with 2 quarterwave added elements. But, > developing the array to provide low VSWR and best squint angle at any > chosen frequency will demant some "field testing". > You probably already knew that. I just wasnt sure. Besides I have wasted > alot of time developing a very similar colinear array for commercial use. > > Jerry KD6JDJ > > Article: 222992 of rec.radio.amateur.antenna From: "danda" References: Subject: Re: Any recomends on a Auto tuner Message-ID: Date: Sun, 02 Apr 2006 06:44:33 GMT "Jerry" wrote in message news:b6HXf.5631$z7.1805@bignews3.bellsouth.net.. I have the Pro100 and it will try to tune up a garage door! There are few things it won't try to tune. I have the Cobra Ultralite Senior antenna and I really enjoy the ability to go from 160-10 Meters with one wire antenna. 73 Jerry K4KWH Jerry I see you have a Cobra Ultralite senior what is your opinion of it I have just hade one shipped to the UK, what is your opinion of it? waiting for a good weekend to get it up in the air. Article: 222993 of rec.radio.amateur.antenna From: "danda" Subject: Cobra Ultrlite Senior Message-ID: Date: Sun, 02 Apr 2006 07:06:10 GMT Has anybody used a Cobra Ultaralite antenna any opinions please Article: 222994 of rec.radio.amateur.antenna Date: Sun, 02 Apr 2006 04:49:13 -0600 From: BKR Subject: Re: how to reduce ghost from a wall mounted uhf antenna References: <1143969836.641578.171360@g10g2000cwb.googlegroups.com> Message-ID: <442fac47@nntp.zianet.com> What sort of antenna is it? A corner reflector, yagi or UHF periodic antenna should provide some relief. beerismygas@yahoo.com wrote: > i have a uhf tv antenna on my balcony. i am getting ghosting. > > i think the ghosting is from signals bouncing off the balcony wall and > hitting the antenna a second time. > > apart from building a 100' tower to raise my antenna into the open sky, > is there any way to keep the wall from reflecting ? can i put some sort > of foil behind the antenna to block it out ?or cover the wall with some > non reflective material? > > thx > Article: 222995 of rec.radio.amateur.antenna Date: Sun, 02 Apr 2006 04:56:50 -0600 From: BKR Subject: Re: paint antenna? References: Message-ID: <442fae11$1@nntp.zianet.com> There is a big problem with that idea because common brick absorbes water content and will provide a very lossy substrate. The resonant frequency will also be affected due to capacitance. ml wrote: > just read a article someplace about a new conductive paint that is going > to be used by different sources (pvt/mil) to in effect paint an antenna > on a surface. once such use was an 'orbiting' blimp , planes etc to > repete signals > > > ok so i wonder my roof has a flat brick wall it's 40ft tall 40ft wide > > if i painted a antenna design think i'd get any useful performance in at > least one direction? > > unf it didn't state any spec's but it's commercial > > > just really thinking out louad how a antenna w/little profile but > otherwise large surfacce area might work Article: 222996 of rec.radio.amateur.antenna From: "Richard Fry" References: <1143969836.641578.171360@g10g2000cwb.googlegroups.com> Subject: Re: how to reduce ghost from a wall mounted uhf antenna Date: Sun, 2 Apr 2006 06:32:35 -0500 Message-ID: <442fb58c_4@newsfeed.slurp.net> wrote >i have a uhf tv antenna on my balcony. i am getting ghosting. > > i think the ghosting is from signals bouncing off the balcony wall and > hitting the antenna a second time. ______________ An r-f reflection capable of producing a ghost in an analog TV broadcast signal needs to have something like a 1/2 microsecond minimum propagation delay from the direct signal. That takes a path difference of ~492 feet, so your balcony wall probably is not be the source of your ghost. More likely it is from a reflecting surface (building, sign, water tower, etc) somewhere near the direct path from the TV tx to your antenna. You might try a corner reflector or yagi, and aim it in various directions (not necessarily toward the TV tx) looking a for a cleaner overall signal. RF Article: 222997 of rec.radio.amateur.antenna From: "Richard Fry" References: <1143759372.007217.65370@g10g2000cwb.googlegroups.com> <4HAXf.10092$dU3.6515@trnddc01> Subject: Re: Adjusting a colinear antenna Date: Sun, 2 Apr 2006 07:53:43 -0500 Message-ID: <442fc892_5@newsfeed.slurp.net> "Jerry Martes" wrote > A properly done colinear array of 8 half wave elements will sure have a > highly directive pattern in the Elevation plane. With some luck and low > loss components you might get 8 or 9 dBi. But, the pattern will have a > pattern max thats broadside to the axis of the colinear array at only one > frequency. That pattern max will squint up and down (with respect to the > horizon) as the frequency varies from that center frequency. _______________ The change with frequency in the angle of the elevation pattern maximum field is the result of the varying relative r-f phase vs the operating frequency that is applied to the radiating elements in this design. This can be eliminated by using a vertically stacked array of identical radiators fed via an n-way power divider, whose output connects to feed cables of equal electical lengths to each element of the array. The directivity (gain) and sidelobe distribution of this type of array will change with operating frequency, but the elevation angle at which the peak field is directed will remain the same, regardless of the input frequency. This approach is used in broadcast transmit antenna designs giving good signal coverage over large sections of the UHF TV band, or the entire FM band. RF Article: 222998 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Amother look at a choke balun. References: <2ZeXf.1088$dU3.257@trnddc01> Message-ID: Date: Sun, 02 Apr 2006 13:21:13 GMT Reg Edwards wrote: > John, what with the unwanted interference from Richard Clark, you'll > just have to accept the fact that the ferrite material has little or > no effect on transmission through the short length of transmission > line, be it coax or twin-line, wound on the ferrite core. Maybe it would help to say "... on transmission of differential signals through the short length of transmission line ...". -- 73, Cecil http://www.qsl.net/w5dxp Article: 222999 of rec.radio.amateur.antenna From: "Jerry Martes" References: <1143759372.007217.65370@g10g2000cwb.googlegroups.com> <4HAXf.10092$dU3.6515@trnddc01> <442fc892_5@newsfeed.slurp.net> Subject: Re: Adjusting a colinear antenna Message-ID: Date: Sun, 02 Apr 2006 14:30:33 GMT "Richard Fry" wrote in message news:442fc892_5@newsfeed.slurp.net... > "Jerry Martes" wrote >> A properly done colinear array of 8 half wave elements will sure have a >> highly directive pattern in the Elevation plane. With some luck and low >> loss components you might get 8 or 9 dBi. But, the pattern will have a >> pattern max thats broadside to the axis of the colinear array at only one >> frequency. That pattern max will squint up and down (with respect to the >> horizon) as the frequency varies from that center frequency. > _______________ > > The change with frequency in the angle of the elevation pattern maximum > field is the result of the varying relative r-f phase vs the operating > frequency that is applied to the radiating elements in this design. > > This can be eliminated by using a vertically stacked array of identical > radiators fed via an n-way power divider, whose output connects to feed > cables of equal electical lengths to each element of the array. The > directivity (gain) and sidelobe distribution of this type of array will > change with operating frequency, but the elevation angle at which the peak > field is directed will remain the same, regardless of the input frequency. > > This approach is used in broadcast transmit antenna designs giving good > signal coverage over large sections of the UHF TV band, or the entire FM > band. > > RF Hi Richard Do you have a sketch of the harness a guy might use to feed that 8 dipole colinear array? Remember, this colinear antenna is mounted on the back of a Lap Top Computer for WiFi use. Jerry > Article: 223000 of rec.radio.amateur.antenna From: "David J Windisch" References: <2ZeXf.1088$dU3.257@trnddc01> <0mct22dtjmgg0rkrr16f16ukbjdtrgntfk@4ax.com> <9tvt22l88ibl2lp37o1tgbg4trohq9mldh@4ax.com> Subject: Re: Amother look at a choke balun. Message-ID: Date: Sun, 02 Apr 2006 14:39:06 GMT John, you've been snookered ;o))) 73, Dave, N3HE "John - KD5YI" wrote in message news:gdEXf.1587$Py4.705@trnddc06... > Richard Clark wrote: >> On Sat, 01 Apr 2006 22:13:05 GMT, John - KD5YI >> wrote: >> >> >>>I am afraid I do not understand the meaning of "bafflegab". >> >> >> Hi John, >> BIGSNIPOFWELLCRAFTEDBAFFLEGAB how wikipedia >> trails in social currency. >> >> 73's >> Richard Clark, KB7QHC > > > Richard - > > I must say that the meaning is no clearer to me now. Your explanation > makes no sense to me. I apologize for my lack of understanding. > > Thanks for trying to explain nevertheless. > > Cheers, > John Article: 223001 of rec.radio.amateur.antenna From: "David G. Nagel" Subject: Re: Current through coils Date: Sun, 02 Apr 2006 10:31:23 -0500 Message-ID: <122vrkhlccjcdfa@corp.supernews.com> References: <122rb4p4vmdui0d@corp.supernews.com> <11783-442DB20F-474@storefull-3254.bay.webtv.net> <1143912658.321932.277610@j33g2000cwa.googlegroups.com> <1143918684.221674.276010@i39g2000cwa.googlegroups.com> <442f477d$0$7329$39cecf19@news.twtelecom.net> <88QXf.54712$F_3.23945@newssvr29.news.prodigy.net> Cecil Moore wrote: > Tom Ring wrote: > >> You cannot win an argument with someone that does not acknowledge >> reality. > > > I've found that out, Tom. None of you guys are willing to > answer any technical questions about the material presented > on my web page at: http://www.qsl.net/w5dxp/current.htm, > in particular: http://www.qsl.net/w5dxp/1WLDIP.GIF > > The current through a coil placed in a standing wave > environment either depends upon where it is placed in > that environment or it doesn't. It's not rocket science. > > The gurus have refused to discuss at least 95% of my > technical questions. No amount of personal wise cracks, > like yours above, will erase that fact. Cec; I hate to be the one to break it to you but you are the one they are talking about. When everyone says you are drunk, like down, your drunk. Dave N Article: 223002 of rec.radio.amateur.antenna From: "Richard Fry" References: <1143759372.007217.65370@g10g2000cwb.googlegroups.com> <4HAXf.10092$dU3.6515@trnddc01> <442fc892_5@newsfeed.slurp.net> Subject: Re: Adjusting a colinear antenna Date: Sun, 2 Apr 2006 10:36:08 -0500 Message-ID: <442feea1_5@newsfeed.slurp.net> > Do you have a sketch of the harness a guy might use to feed that 8 > dipole colinear array? Remember, this colinear antenna is mounted on the > back of a Lap Top Computer for WiFi use. ____________ Sorry, not for that application. Article: 223003 of rec.radio.amateur.antenna From: "Tom Donaly" Subject: Re: Coils and Transmission Lines. References: Message-ID: <3gSXf.63583$Jd.40227@newssvr25.news.prodigy.net> Date: Sun, 02 Apr 2006 15:40:47 GMT Cecil Moore wrote: > Reg Edwards wrote: > >> It may be of interest to antagonists in the "current through coils" >> civil war. > > > The nature of traveling wave current and standing wave current > is different. Does your program take that into account? > > The "current through coils" argument boils down to the ones who > understand standing wave currents in a standing wave antenna and > those who refuse to take the time to understand. > > Quoting "Optics", by Hecht: "E(x,t) = 2Eo*sin(kx)*cos(wt) > This is the equation for a STANDING or STATIONARY WAVE, as > opposed to a traveling wave (Fig. 7.10). Its profile does > not move through space. ... [The phase] doesn't rotate at > all, and the resultant wave it represents doesn't progress > through space - it's a standing wave." > > Until the gurus take the time to understand the nature of > standing waves in standing waves antennas, they will keep > committing the same mental blunders over and over. Hecht forgot to put the phase difference in his formula. It's no wonder there's no phase information in your standing waves, Cecil, Hecht left it out. Not only that, but where did he get the idea that it was sin(kx) instead of cos(kx). I understand Hecht is a good old boy, but I'd like to see his derivations. 73, Tom Donaly, KA6RUH Article: 223004 of rec.radio.amateur.antenna From: "Tom Donaly" Subject: Re: Current through coils References: <122rb4p4vmdui0d@corp.supernews.com> <11783-442DB20F-474@storefull-3254.bay.webtv.net> <1143912658.321932.277610@j33g2000cwa.googlegroups.com> <1143918684.221674.276010@i39g2000cwa.googlegroups.com> <442f477d$0$7329$39cecf19@news.twtelecom.net> Message-ID: Date: Sun, 02 Apr 2006 15:45:52 GMT Tom Ring wrote: > Tom Donaly wrote: > >> >> >> Cecil, there are two Corums and they're both Tesla coil >> crackpots. Secondly, Tom is right, you have to have capacitance >> to somewhere or your transmission line analogy becomes mired in >> absurdities. Third, it isn't enough to think something up in >> your head to make a convincing theory, you have to be able to >> predict behavior with it. Finally, you have to understand your >> subject before you even start thinking. I'm surprised you didn't >> even take the time to make a real coil and at least try to >> determine its characteristics before wasting everyone's >> time by starting this thread. >> 73, >> Tom Donaly, KA6RUH > > > Tom, > > You, and everyone else is, as we put it in the midwest, and probably > elsewhere, "pissing into the wind". > > You cannot win an argument with someone that does not acknowledge reality. > > tom > K0TAR If we don't pee into the wind Cecil will end up telling everyone his crackpot theories are received truth, and eventually we'll be reading them in _The ARRL Handbook_. I appreciate the fact that it's a waste of time, otherwise. Entertaining, though. Cecil's an interesting Character. 73, Tom Donaly, KA6RUH Article: 223005 of rec.radio.amateur.antenna From: "Yuri Blanarovich" References: Subject: Re: Coils and Transmission Lines. Message-ID: Date: Sun, 2 Apr 2006 12:07:38 -0400 "Cecil Moore" wrote in message > > Until the gurus take the time to understand the nature of > standing waves in standing waves antennas, they will keep > committing the same mental blunders over and over. > -- > 73, Cecil http://www.qsl.net/w5dxp More astonishing than that, Until the "gurus" put their finger on the coil, or aquarium thermometer, or RF ammeter, or infrared scope and see that the loading coil (in a typical quarter wave resonant whip) is heating up at the bottom, being the reality that defies their "scientwific theories why it shouldn't" - they will keep committing the same mental blunders over and over. What's next? There is less current in a wire (coil) where wire (coil) gets hotter? Let the games begin! Thermometers don't lie, meters don't lie, even EZNEC shows it! So wasaaaaap? Yuri, K3BU Article: 223006 of rec.radio.amateur.antenna From: John - KD5YI Subject: Re: Coils and Transmission Lines. References: Message-ID: Date: Sun, 02 Apr 2006 18:09:41 GMT Reg Edwards wrote: > To satisfy demands for disclosure of the source code of my programs I > have made the source code of program TRANCO_1 available from my > website. > > It may be of interest to antagonists in the "current through coils" > civil war. > > The source code text, which is almost readable using non-proportional > spaced text readers, can be found in "Download Pascal source code from > here" section on the Index page. > ---- > ........................................................... > Regards from Reg, G4FGQ > For Free Radio Design Software go to > http://www.btinternet.com/~g4fgq.regp > ........................................................... There is no "Download Pascal source code from here" section on the Index page. There is a "Get Pascal source code from here" section which lists the following: GRNDWAV3.pas * Groundwave propagation vs frequency, distance and terrain. TOPHAT2.pas * Performance of top-capacitance loaded vertical. PADMATCH.pas * T and Pi resistive-matching and minimum loss pads. I do not see the TRANCO_1 source code listed. 73 John Article: 223007 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Current through coils References: <122rb4p4vmdui0d@corp.supernews.com> <11783-442DB20F-474@storefull-3254.bay.webtv.net> <1143912658.321932.277610@j33g2000cwa.googlegroups.com> <1143918684.221674.276010@i39g2000cwa.googlegroups.com> <442f477d$0$7329$39cecf19@news.twtelecom.net> <88QXf.54712$F_3.23945@newssvr29.news.prodigy.net> <122vrkhlccjcdfa@corp.supernews.com> Message-ID: <8uUXf.51202$2O6.38100@newssvr12.news.prodigy.com> Date: Sun, 02 Apr 2006 18:12:20 GMT David G. Nagel wrote: > I hate to be the one to break it to you but you are the one they are > talking about. I know that, Dave. At best it is the pot calling the kettle black. At worst, it's just another falsehood, one of many. The problem here is not "Current through coils". The problem is that a lot of the gurus are completely ignorant of the nature of standing wave current and refuse to alleviate their ignorance. -- 73, Cecil http://www.qsl.net/w5dxp Article: 223008 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Coils and Transmission Lines. References: <3gSXf.63583$Jd.40227@newssvr25.news.prodigy.net> Message-ID: Date: Sun, 02 Apr 2006 18:39:45 GMT Tom Donaly wrote: > Hecht forgot to put the phase difference in his formula. > It's no wonder there's no phase information in your > standing waves, Cecil, Hecht left it out. You are mistaken. If Hecht left it out then so did Gene Fuller. I suggest you listen to Gene when he says: Regarding the cos(kz)*cos(wt) terms in the standing wave equation: > Gene Fuller, W4SZ wrote: >> In a standing wave antenna problem, such as the one you describe, there is no >> remaining phase information. Any specific phase characteristics of the traveling >> waves died out when the startup transients died out. >> >> Phase is gone. Kaput. Vanished. Cannot be recovered. Never to be seen again. >> >> The only "phase" remaining is the cos (kz) term, which is really an amplitude >> description, not a phase. > Not only > that, but where did he get the idea that it was sin(kx) instead > of cos(kx). I understand Hecht is a good old boy, but I'd like to > see his derivations. Apparently, you are ignorant of the difference in conventions between optics and RF engineering. In optics, there is no current so there is no current changing phase at an open circuit. In optics, the M-field changes directions but not phase. In RF engineering, a change in direction of the H-field is considered to be a 180 degree phase shift. Both conventions are correct as long as one understands them. Your strange statement about Hecht above just proves your ignorance. -- 73, Cecil http://www.qsl.net/w5dxp Article: 223009 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Coils and Transmission Lines. References: <1143998691.460370.255530@i40g2000cwc.googlegroups.com> Message-ID: Date: Sun, 02 Apr 2006 18:48:58 GMT w8ji@akorn.net wrote: > No one I have seen has every said one tuern can't get hotter than > another turn in a loading coil. If the current is equal at both ends, how does one turn possibly get hotter than another turn? > It's all been explained over and over again. Repeating a wrong answer 1000 times doesn't make it right. And that's exactly what you do. > If the termination impedance of the coil is very high compared to > shunting impedances inside the coil to the outside world, a coil can > have phase shift in current at each terminal and it can have uneven > current distribution. > > This is not caused by standing waves or "electrical degrees" the coil > replaces, but rather by the displacement currents which can provide a > path for the through currents. It is caused by where the coil is installed in the standing wave environment, proved on my web page at: http://www.qsl.net/w5dxp/current.htm That the proof is accurate explains why you refuse to discuss the technical facts surrounding it. > The problem is Cecil attributes it all to standing waves, and not to > the inductor's design. Given the fixed design of a single inductor example, I can change which end the current is highest by simply placing in in the proper place in the standing wave environment, the environment that you refuse to discuss. -- 73, Cecil http://www.qsl.net/w5dxp Article: 223010 of rec.radio.amateur.antenna From: "Jim" References: <1143759372.007217.65370@g10g2000cwb.googlegroups.com> <4HAXf.10092$dU3.6515@trnddc01> <442fc892_5@newsfeed.slurp.net> <442feea1_5@newsfeed.slurp.net> Subject: Re: Adjusting a colinear antenna Message-ID: <67VXf.3640$qe7.109@trnddc04> Date: Sun, 02 Apr 2006 18:56:02 GMT Richard, The antenna that I am looking to build is not for Wi-Fi, but for 840mHz range and will be mounted outside on a pole about 25 feet high. Tnx Jim "Richard Fry" wrote in message news:442feea1_5@newsfeed.slurp.net... >> Do you have a sketch of the harness a guy might use to feed that 8 >> dipole colinear array? Remember, this colinear antenna is mounted on >> the back of a Lap Top Computer for WiFi use. > ____________ > > Sorry, not for that application. Article: 223011 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Coils and Transmission Lines. References: Message-ID: Date: Sun, 02 Apr 2006 19:37:20 GMT Ian White GM3SEK wrote: > The argument is specifically about Cecil's attempts to explain the > evidence, using his own particular ideas about "standing wave antennas". > He makes it kinda work for the cases he wants to think about, but in > other cases it gets things fundamentally wrong - and that isn't good > enough. That's just not true, Ian. If the distributed network model agrees with the lumped circuit model, then the lumped circuit model is being used in an appropriate situation. If the distributed network model disagrees with the lumped circuit model, then the lumped circuit model is being used in an inappropriate situation. The distributed network model is always right when it disagrees with the lumped circuit model. The distributed network model is a *superset* of the lumped circuit model. To quote Dr. Corum: "Distributed theory encompasses lumped circuits and always applies." And before you dismiss Dr. Corum as a "crackpot", as others have, please pay attention to the references for his peer-reviewed paper published by the IEEE: Kraus, Terman, Ryder, Ramo & Whinnery, Born & Wolf. The problem is that the lumped circuit model is being used in inappropriate situations because you and others do not understand how standing wave current in standing wave antennas differs from traveling wave current in traveling wave antennas. To compound the error, none of you are willing to discuss it from a technical standpoint. That unwillingness reeks of religion, not science. Someone we both know and respect wonders why you are so closed minded. I suggested he contact you by email. If you, or anyone else, were willing to discuss the nature of standing waves from a technical standpoint, most of the present argument would be resolved by that discussion. I'm willing to discuss it. Why aren't you? It is entirely possible that I am abusing the distributed network model, but nobody will be able to prove it unless they engage in a discussion of standing waves. -- 73, Cecil http://www.qsl.net/w5dxp Article: 223012 of rec.radio.amateur.antenna From: "Yuri Blanarovich" References: <85ydnUdYMN0xMbzZnZ2dnUVZ_vednZ2d@adelphia.com> <1223dvop83mkq9a@corp.supernews.com> <12244tdjaher025@corp.supernews.com> <1224i2p9j0tr33d@corp.supernews.com> <9oidndktkuKTQ7_ZnZ2dnUVZ_vudnZ2d@adelphia.com> <1227bed4qaf0t71@corp.supernews.com> Subject: Re: Current through coils Message-ID: Date: Sun, 2 Apr 2006 16:00:16 -0400 "Ian White GM3SEK" wrote in message news:g3gPxvEsEYJEFAUl@ifwtech.co.uk... > From the beginning, then: snippydidudaa > > As we have seen, if the whip is loaded by pure inductance only, there is > no change in current between the two terminals of the inductance - but > there's a big step increase in voltage. At the upper terminal, the current > is the same but the voltage is very high, so we're into a much > higher-impedance environment. > Reality check here. I need explanation how the above could happen. "Current stays the same ... and the big step increase in voltage." As far as "idiot" professors taught me, (current x voltage) = power. So, am I to discover that the pure inductance is better than perpetual motion amplifier of power? More power coming out of the coil than going in? Eureka!!! How could I overlook that? :-) > As we go further up towards the top of the whip, current magnitude has to > taper off to zero at the very top. This also means that the voltage > magnitude has to increase even more as we approach the top of the whip. > So it tapers across the straight piece of conductor, but not in the wound up conductor? Magine that! Reality check #2. > Single-point loading by pure inductance has thus created almost all the > major features that we see in a practical centre-loaded whip - > particularly the big step change in voltage across the loading coil. > So the "teaching" is that there is a big step change in the voltage across the coil, but no-way change in the current? Who's law, theory, invention is that? (We are still talking about real RF currents, not "my voltage" and "your invincible, steady, unchengeable current"?) > What we don't see in a practical antenna are exactly equal current > magnitudes and zero phase shift between the terminals of a real-life > loading coil - but that is ONLY because a real-life coil is not a pure > inductance. The harder we try to reach that ideal (by winding the coil on > a high-permeability toroidal core which confines the external fields and > allows the whole thing to become very small), the closer the currents at > the bottom of the coil come to being equal. Solid theory and accurate > measurements come together to support each other. The only gap between > theory and practice is due to our inability to construct a pure inductance > that has no other complicating properties. > The whole argument is about REAL LIFE loading coil in the antennas. But you obviously ignored or not noticed that W9UCW also used toroid coil and found very similar results, about 40 - 60 % less current at the top end and NOT (just about) EQUAL as the arguments IS about. Who cares about or needs "pure" inductance? What for? Just to twist the argument that "gurus" were right? Gimme a break! > If we can agree about pure inductive loading, we all have a firm place to > stand. Then we can then put back those "other" complicating properties of > a real-life loading coil, and see what difference they make. As firm as driving my Buick in the free space! Halooooo! Go measure it! See what it IS! Then if the coil IS hot at both ends, or you measure current almost equal at both ends, describe the experiment so we can verify it and we will rest our case and admit to be a bunch dummies stuck on stooooopid! (We are still talking about quarter wave resonant, loaded typical mobile antenna with loading coil about 2/3 up the 8 - 10 foot mast, no detours to la-la pure inductance in the vacuum with no resistance, free space no-nothing thing :-) And as Cecil mentioned, we are not disputing that there is no capacitance to the surroundings, or no losses through resistance and radiation amounting to SMALL (you put figure on it Richard) drop, versus more SIGNIFICANT (like 40 -60%) drop across the loading coil. I am sorry to beeing away for a zilion of posts, but real life is more important and I am trying to be in touch. I will try to find the W8JI response to my first (start from scratch) post in order to find where I went wrong, if he will engage in some technical discussion. I hate to be wrong. Happy second April foolsday! Yuri, K3BU.us > [1] This principle of "conservation of charge" is also the underlying > principle of Kirchhoff's current law. If you connect three ordinary wires > together, the current flowing into the junction from one wire must be > exactly and instantaneously balanced by the currents flowing in or out on > the other two wires. If this was not so, there would have to be some means > of adding, storing or losing electrons at the junction... which > contradicts our initial assumption of three simple wires with no special > properties. > > It is not strictly accurate to say that Kirchhoff's current law applies to > pure inductance, but the underlying principle of "conservation of charge" > does apply. > -- > 73 from Ian GM3SEK 'In Practice' columnist for RadCom (RSGB) > http://www.ifwtech.co.uk/g3sek What "other two wires"? I see RF current flowing through one wire (base) then another wire in series (coil) than another one in series (tip - whip) then "finding" the tip, aka END reflecting form it, and going back, creating standing wave with proper current AND voltage distribution according to sine (or if you like cosine) function. What about energy (power) conservation law? How can coil "make" more voltage at the top, while "having" the same current on the top as at the bottom? 73 + 88 from Yuri K3BU, jus' inquiring mind Article: 223013 of rec.radio.amateur.antenna From: "Tom Donaly" Subject: Re: Coils and Transmission Lines. References: <3gSXf.63583$Jd.40227@newssvr25.news.prodigy.net> Message-ID: Date: Sun, 02 Apr 2006 20:20:00 GMT Cecil Moore wrote: > Tom Donaly wrote: > >> Hecht forgot to put the phase difference in his formula. >> It's no wonder there's no phase information in your >> standing waves, Cecil, Hecht left it out. > > > You are mistaken. If Hecht left it out then so did Gene Fuller. > I suggest you listen to Gene when he says: Regarding the > cos(kz)*cos(wt) terms in the standing wave equation: > >> Gene Fuller, W4SZ wrote: >> >>> In a standing wave antenna problem, such as the one you describe, >>> there is no remaining phase information. Any specific phase >>> characteristics of the traveling waves died out when the startup >>> transients died out. >>> >>> Phase is gone. Kaput. Vanished. Cannot be recovered. Never to be seen >>> again. >>> >>> The only "phase" remaining is the cos (kz) term, which is really an >>> amplitude description, not a phase. > > >> Not only >> that, but where did he get the idea that it was sin(kx) instead >> of cos(kx). I understand Hecht is a good old boy, but I'd like to >> see his derivations. > > > Apparently, you are ignorant of the difference in conventions between > optics and RF engineering. In optics, there is no current so there is > no current changing phase at an open circuit. In optics, the M-field > changes directions but not phase. In RF engineering, a change in > direction of the H-field is considered to be a 180 degree phase shift. > Both conventions are correct as long as one understands them. Your > strange statement about Hecht above just proves your ignorance. Whatever. I'd still like to see his derivations. In your case, you're using the wrong equation anyway. What you really want is Beta*l, or the radian length of your transmission line. You can get that if you know, or can measure the usual parameters in the transmission line impedance equation, using that equation to solve for Beta*l. That won't prove your theory because you still haven't shown that any one transmission line model is unique in terms of substituting for your coil, but at least it'll give you something to do. 73, Tom Donaly, KA6RUH Article: 223014 of rec.radio.amateur.antenna From: "Yuri Blanarovich" References: <1143998691.460370.255530@i40g2000cwc.googlegroups.com> Subject: Re: Coils and Transmission Lines. Message-ID: Date: Sun, 2 Apr 2006 16:56:57 -0400 wrote in message news:1143998691.460370.255530@i40g2000cwc.googlegroups.com... > > Yuri Blanarovich wrote: >> More astonishing than that, Until the "gurus" put their finger on the >> coil, >> or aquarium thermometer, or RF ammeter, or infrared scope and see that >> the >> loading coil (in a typical quarter wave resonant whip) is heating up at >> the >> bottom, being the reality that defies their "scientwific theories why it >> shouldn't" - they will keep committing the same mental blunders over and >> over. > > Yuri, > > No one I have seen has every said one tuern can't get hotter than > another turn in a loading coil. > > For example, I can take a piece of airdux and short a single turn > anywhere in the coil. That turn and the turns around it will get very > hot, often even melting the form and discoloring the wire, even with > modest power applied in a resoant circuit. > > I had my 75 watt Novice rig melt miniductor in certain spots way back > in the very early 60's. > Stop right here. We are talking about perfectly good coil (Hustler 80m resonator) no shorts between the turns, ne end effect shorting out turns (and if so, then both ends are the same). Perfectly good coil, with wire insulation intact, uniformly wound, uniform wire diameter (constant resistance) good insulation, until wire gets red hot, and covered with what appears to be heat shrink tubing. When I applied about 600W to it, the coil obviously started to overhead, with obvious tapered patter of heat distribution (no shorted turn culprit) with most intense on the bottom, slowly tapering towrds the top. No signs of similar "melting" at the top (to blame "shorted" turn from the top cap), nor anywhere in the middle to indicate shorted turn. If you do not believe that this could happen, than say so and I will provide the evidence, I will melt another coil. If you believe and can relate some of your melting to mirror this case, than please explain what else can cause this besides the current being SIGNIFICANTLY higher at the bottom than at the top. What I know from the thermodynamics, that heat rises to the top. If the current was (almost) equal, then the coil would be heating up and starting to melt uniformly, with actually more pronounced effect at the top, due to the rising and adding heat from the lower part of the coil (no upside Buick here). So lets talk specifics of the argument and not detours, please! > The problem is wild theories are created from small grains of truth or > factoids. It is the wild theories that people question. > I question reality that I experienced, claims to the contrary ("it can't be") and theories rode in support of pro and con. > In an effort to support the wild claims, there seems to be an effort to > dismiss anything but the wild theories. Here is how it goes: > 1.) My Hustler antenna loading coil (known to be a poor electrical > design) melted the heatshrink at the bottom > Maybe poor electrical design, but perfectly sound coil, with uniform insulated wire, wound on perfect cylinder. It was Hustler coil with its physical properties and heatshrink tubing over the turns that magnified the effect and attracted my attention. > 2.) This must be becuase there is only high current at the bottom of > every loading coil. > I will disregard the rest of your post as a irrelevant crap, typical of your prior riding in on a high horse, ridiculing and pontificating. If you can stay on the technical side of the discussion we will continue, if you can't, then play the "guru" and we are all "stay stoooopid"! Yuri > 3.) This must be because the standing waves on the antenna all wind up > in the loading coil. > > 4.) This must mean all loading coils act just like they are the x > degrees of antenna they replace. > > 5.) This is why, no matter what we do with loading coil Q, efficiency > doesn't change much. > > 6.) We will write a IEEE paper about this astounding fact, since all > the texbooks about loading coils or inductors in general must be wrong > > 7.) Anyone who point out it is imperfections in the design of the > system that cause this must be wrong, since I saw the coil get hot > > 8.) Anyone who disagrees with me must think himself a guru, and be > incapable of learning or understanding how things work > > 9.) I know all this because the bottom of the coil gets hot in my > antenna > > What's next? There is less current in a wire (coil) where wire (coil) > gets >> hotter? >> Thermometers don't lie, meters don't lie, even EZNEC shows it! So >> wasaaaaap? > > It's all been explained over and over again. > > If the termination impedance of the coil is very high compared to > shunting impedances inside the coil to the outside world, a coil can > have phase shift in current at each terminal and it can have uneven > current distribution. > > This is not caused by standing waves or "electrical degrees" the coil > replaces, but rather by the displacement currents which can provide a > path for the through currents. > > Reg actually explained this very well, as has Roy, Tom D, Gene, Tom > ITM, Ian, and a half dozen others. > > The reason you keep beating your head against the wall is you want to > think the conclusions you formed were correct. > > If I wanted to design a loading coil that has virtually 100% current > taper, I could. If I wanted to design one with virtually no taper, I > could. I could actually have an antenna of a fixed height and by making > various styles of loading coils go anywhere from nearly uniform > distribution at each end of the coil to some significant taper. > > The problem is Cecil attributes it all to standing waves, and not to > the inductor's design. You seem to be doing the same. > > Since we won't agree with your wrong theories, you then conclude we are > saying step one is wrong and you never saw what you saw. Step one is > fine. Step two is where everything you say falls apart. > > 73 Tom > Article: 223015 of rec.radio.amateur.antenna From: "Yuri Blanarovich" References: Subject: Re: Coils and Transmission Lines. Message-ID: Date: Sun, 2 Apr 2006 17:08:28 -0400 "Ian White GM3SEK" wrote in message news:QKhTu7Q+xAMEFAZL@ifwtech.co.uk... > Yuri Blanarovich wrote: >>"Cecil Moore" wrote in message > >>> Until the gurus take the time to understand the nature of >>> standing waves in standing waves antennas, they will keep >>> committing the same mental blunders over and over. >>> -- >>> 73, Cecil http://www.qsl.net/w5dxp >> >> >>More astonishing than that, Until the "gurus" put their finger on the >>coil, >>or aquarium thermometer, or RF ammeter, or infrared scope and see that the >>loading coil (in a typical quarter wave resonant whip) is heating up at >>the >>bottom, being the reality that defies their "scientwific theories why it >>shouldn't" - they will keep committing the same mental blunders over and >>over. >> >>What's next? There is less current in a wire (coil) where wire (coil) gets >>hotter? >>Let the games begin! >> >>Thermometers don't lie, meters don't lie, even EZNEC shows it! So >>wasaaaaap? > > If you're looking for an argument, you're looking in the wrong place. > > Nobody denies the raw evidence, like the fact that some loading coils get > hotter at the bottom than at the top... and the fact that some other coils > don't (or nowhere near as much). > So what is the reason? Isn't the higher current through the same resistance wire cause of more heat development? We now why and Cecil explained it. Depends where the coil is placed in the antenna and its place on the cosine current distribution curve. It has been shown epxerimentally and also by EZNEC when modeled properly as solenoid or loading stub. Yea, the "other" zero size coils don't show that, EZNEC confirms that. > There are good explanations for everything you see. But the only valid > explanations are the ones that account for *all* the facts about *all* > types of loading coils. > We are talking about typical loading coils in typical antennas, no need to go to "all" that would skew that and "prove" it ain't so. > The argument is specifically about Cecil's attempts to explain the > evidence, using his own particular ideas about "standing wave antennas". > He makes it kinda work for the cases he wants to think about, but in other > cases it gets things fundamentally wrong - and that isn't good enough. > As far as I see, it is not just Cecil's own idea or discovery, he attempted to explain the obvious effect and in the process found that there is more support and standing wave theory by others. So we have an effect, and (close enough) explanation and way of modeling it (close enough), but have a bunch of people that cling to "she's flat". Yuri, K3BU/m > > -- > 73 from Ian GM3SEK 'In Practice' columnist for RadCom (RSGB) > http://www.ifwtech.co.uk/g3sek Article: 223016 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Coils and Transmission Lines. References: <3gSXf.63583$Jd.40227@newssvr25.news.prodigy.net> Message-ID: Date: Sun, 02 Apr 2006 21:10:45 GMT Tom Donaly wrote: > Whatever. I'd still like to see his derivations. "Optics", by Hecht, 4th edition, page 289. The intensity of a light beam is associated with the E-field so Hecht's equations are in relation to the E-field. Speaking of the light standing wave: "The composite disturbance is then: E = Eo[sin(kt+wt) + sin(kt-wt)] Applying the indentity sin A + sin B = 2 sin 1/2(A+B)*cos 1/2(A-B) E(x,t) = 2*Eo*sin(kx)*cos(wt)" Hecht says the standing wave "profile does not move through space". I have said the RF standing wave current profile does not move through a wire. Hecht says the standing wave phasor "doesn't rotate at all, and the resultant wave it represents doesn't progress through space - it's a standing wave." I have said the same thing about the RF standing wave current phasor. Hecht says the standing wave transfers zero net energy. I have said the same thing about RF standing waves. -- 73, Cecil http://www.qsl.net/w5dxp Article: 223017 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Coils and Transmission Lines. References: Message-ID: Date: Sun, 02 Apr 2006 21:18:01 GMT Yuri Blanarovich wrote: > It has been shown epxerimentally and also by > EZNEC when modeled properly as solenoid or loading stub. Yea, the "other" > zero size coils don't show that, EZNEC confirms that. As a data point, the results of modeling a coil as a lumped inductor Vs a helical coil are NOT the same in EZNEC. EZNEC disagrees with itself. I am much more inclined to trust the helically modeled inductance than the lumped inductance. As Dr. Corum says: "Distributed theory encompasses lumped circuits and always applies." In other words, the Distrubuted network model is a superset of the lumped circuit model. -- 73, Cecil http://www.qsl.net/w5dxp Article: 223018 of rec.radio.amateur.antenna From: Roy Lewallen Subject: Re: What is an EH antenna Date: Sun, 02 Apr 2006 14:19:09 -0700 Message-ID: <1230fue8b8chkbf@corp.supernews.com> References: <1143908604.326393.313760@j33g2000cwa.googlegroups.com> <2yUXf.18997$B_1.11490@edtnps89> Frank's wrote: > > I think the EH is the same idea as the CFA; in which case the following > paper > says it all: http://www.fi.uba.ar/materias/6654/download/CFAantenna.pdf. > > It is hard to imagine going to these lengths to debunk nonsense, but I guess > it is the only way. And, as we periodically see here, even going to these lengths aren't completely adequate. Roy Lewallen, W7EL Article: 223019 of rec.radio.amateur.antenna From: "Yuri Blanarovich" References: Subject: Re: Coils and Transmission Lines. Message-ID: Date: Sun, 2 Apr 2006 17:49:30 -0400 "Richard Clark" wrote in message news:cs5032dv5sfba3hagm79obmcnrvs4e9iik@4ax.com... > On Sun, 2 Apr 2006 12:07:38 -0400, "Yuri Blanarovich" > wrote: > >>Thermometers don't lie, meters don't lie, even EZNEC shows it! So >>wasaaaaap? > > Hi Yuri, > > That's a good question. The last you had to say, two years ago, was > you were waiting for the snow to melt to provide a better measure. > > It must have been a particularly long and cold winter these two years. > > 73's > Richard Clark, KB7QHC No, but I got cut off the NG by AOL's dropping NGs and therefore lost touch with the severity of the problem. Also got too busy with real life, which I considered more important and didn't even dream that this still would be the problem. I though that some of the unbelievers would by now done it, saw it, realized they were wrong and confessed. Apparently not. So I am glad to be still around and will try to either get educated or contribute to setting the record straight and correct the fallacies that are out there. Sooo, nobody would try to do the experiment and SEE it, but rather keep chasing the gay electron phasors charged with Kirchoffs through three way intersections and blame Bush for it? Yuri, K3BU.us Article: 223020 of rec.radio.amateur.antenna From: "Yuri Blanarovich" References: <1223dvop83mkq9a@corp.supernews.com> <12244tdjaher025@corp.supernews.com> <1224i2p9j0tr33d@corp.supernews.com> <9oidndktkuKTQ7_ZnZ2dnUVZ_vudnZ2d@adelphia.com> <1227bed4qaf0t71@corp.supernews.com> Subject: Re: Current through coils Message-ID: Date: Sun, 2 Apr 2006 18:34:11 -0400 Richard Clark challenged me: > > Didn't you start a new thread to clear out the cobwebs? That seems to > have gone the way of the dodo. > > > Hi Yuri, > > Instead of chewing old gum over and over again, why not simply fulfill > a promise offered two years ago? > Yea, the dodo was the contest I was trying to beat another record and then the fricken taxes came. I will dust off my whips and coils and do some 'sperimenting. But where are all the gurus? Nobody got mobile antenna and can do crude "feel the turns" 'speriment? Must be too busy with charger 'lectrons, Eh?! Yuri, K3BU Article: 223021 of rec.radio.amateur.antenna From: "Yuri Blanarovich" References: <85ydnUdYMN0xMbzZnZ2dnUVZ_vednZ2d@adelphia.com> <1223dvop83mkq9a@corp.supernews.com> <12244tdjaher025@corp.supernews.com> <1224i2p9j0tr33d@corp.supernews.com> <9oidndktkuKTQ7_ZnZ2dnUVZ_vudnZ2d@adelphia.com> <1227bed4qaf0t71@corp.supernews.com> Subject: Re: Current through coils Message-ID: Date: Sun, 2 Apr 2006 18:41:35 -0400 "Ian White GM3SEK" wrote in message news:qoJ9mFWckDMEFAN3@ifwtech.co.uk... > Yuri Blanarovich wrote: >> >>"Ian White GM3SEK" wrote in message >>news:g3gPxvEsEYJEFAUl@ifwtech.co.uk... >> >>> From the beginning, then: >>snippydidudaa >>> >>> As we have seen, if the whip is loaded by pure inductance only, there is >>> no change in current between the two terminals of the inductance - but >>> there's a big step increase in voltage. At the upper terminal, the >>> current >>> is the same but the voltage is very high, so we're into a much >>> higher-impedance environment. >>> >> >>Reality check here. I need explanation how the above could happen. >>"Current >>stays the same ... and the big step increase in voltage." As far as >>"idiot" >>professors taught me, (current x voltage) = power. So, am I to discover >>that the pure inductance is better than perpetual motion amplifier of >>power? >>More power coming out of the coil than going in? Eureka!!! How could I >>overlook that? :-) >> > > Your professor would have told you that you "overlooked" the phase shift > in the voltage. > > The rest is just more of the same kind of name-calling. You didn't really > read what I wrote, and you don't really want to hear any answers. All you > really want is a shouting match. Well, tough, you don't get one. > -- > 73 from Ian GM3SEK 'In Practice' columnist for RadCom (RSGB) > http://www.ifwtech.co.uk/g3sek Yep, when we try to argue the case, it ends up like this. So you know what I read, but you would not want to explain, enlighten this "dummy" what is going on, eh? Uhm, the phase shift is different for current and different for voltage, or you claim that current distribution curve would be way different from the voltage distribution curve? Can you draw the picture of current and voltage distribution in the case in question or provide the file for EZNEC or whateverNEC? Got it! Yuri, K3BU Article: 223022 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Current through coils References: <122rb4p4vmdui0d@corp.supernews.com> <11783-442DB20F-474@storefull-3254.bay.webtv.net> <122rep9k2fqc49d@corp.supernews.com> <8Niof3FsOiLEFAkM@ifwtech.co.uk> <0MUXf.51208$2O6.20901@newssvr12.news.prodigy.com> <2sM63YaI$EMEFAeb@ifwtech.co.uk> Message-ID: Date: Mon, 03 Apr 2006 00:41:25 GMT Ian White GM3SEK wrote: > Cecil Moore wrote: >> RF current switches from a different kind of behavior than DC current. > > True, but irrelevant. You are asking for RF current to switch its > behaviour while still being RF current. Standing wave RF current does not exhibit the same behavior as traveling wave RF current. If you understood the formulas, you would understand my statement. > where Ipk(z) is the peak value of the current at point z. The cos(wt) > term represents the cyclical time dependence of the back-and-forth > movement of electrons; it has no dependence on z. Therefore, the phase of the standing wave current has no dependence on z. In fact, for a 1/2WL thin-wire dipole the phase is fixed at zero degrees no matter what is the value of z. Moral: Standing wave current phase cannot be used to measure the delay through a piece of wire, much less the delay through a coil. But that's exactly what W7EL measured. Now do you see why those measurements were meaningless? THE PHASE OF THE CURRENT IN AND AROUND A LOADING COIL HAS NO DEPENDENCE ON Z. Think about the implications of your statement. > Ipk(z) is simply a scaling factor whose value depends only on the > LOCATION of point z within the antenna. It has NO time dependence. There is an Ipk1(z) at the bottom of the coil. There is an Ipk2(z) at the top of the coil. Both of them have NO time dependence. Therefore, the phase shift between them CANNOT be used to determine the delay through a coil. > The next issue to describe how Ipk varies with the location z along the > wire. The aim of antenna analysis is to find out what the current > distribution along the wire(s) actually is. All the rest of the > antenna's properties can be calculated from this. > > Ipk(z) does not have to be a simple cosine function as you seem to > assume above. I do NOT assume a simple cosine function. I have said many times that the fields of the loading coil warps the current waveform away from the simple cosine function. It puts a bump in the cosine curve but the fact remains that the current envelope magnitude contains the only phase information in the standing wave current. Above, you have essentially agreed with Gene Fuller that zero phase information exists in the standing wave current except in the magnitude. > A cosine function may be a good approximation for very > simple (or simplified) cases; but when the antenna includes a physical > discontinuity such as a loading coil, Ipk(z) will definitely NOT be a > simple cosine function of distance z. So in general it will not be > correct to bundle the z dependence into the same cosine function as (wt). I suggest that the standing wave current for each segment of the antenna can be plotted as has been done at: http://www.k6mhe.com/n7ws/Loaded%20antennas.htm in figure 3 and that a cosine function can be plotted underneath that curve. Associating the bottom of the coil with one point on the cosine curve and the top of the coil with another point on the cosine curve will allow us to make a *rough* estimate of the delay through the coil. The cosine curve doesn't disappear - it is just warped by the current distribution through the coil. > There are several methods of finding the current distribution. If you > choose a method based on forward, reflected and standing waves (which > can be done), the "standing wave" is simply a plot of Ipk as a function > of location z. Ipk(z) is a scalar quantity representing the peak > magnitude of the current, and its only dependence is on LOCATION. It is > not an alternating RF current because it has no time dependence. Yet W7EL used that current with no time dependence to try to measure the delay through a coil. I don't recall you objecting. > "Current" remains what it always was: simply the movement of charge > (electrons). If it's an alternating RF current, the cos(wt) term > describes how the charge moves cyclically forward and back past the > observation point. A loading coil, the RF ammeter or the > current-transformer measuring probe all respond to exactly the same > cyclical back-and-forth movement of charge. Yes, but two RF ammeters gives us a different and more complete view of reality. In a traveling wave antenna, the two RF ammeters would read the same value. In a standing wave antenna, the values read by the two RF ammeters depend upon where they are located. In the 1WL standing wave antenna at: http://www.qsl.net/w5dxp/1WLDIP.GIF, an RF ammeter located at point B might read one amp. An identical RF ammeter located at point D will read zero amps. > In the standing wave analysis, the current is still the net movement of > charge, ie the instantaneous difference between the forward and > reflected currents. There is no net transfer of energy in a pure standing wave. As Hecht says: "Its profile does not move through space." Nor does it move through a wire. Here's the above 1WLDIP.GIF wire replaced by a loading coil. |----1/4WL---|-1/4WL-|----------1/2WL------------| ------A------B-/////-D-------------fp------------- An RF ammeter placed at B may read one amp. An identical RF ammeter placed at D will read zero amps. How can one amp be "flowing" out of the top of the coil while zero amps is "flowing" into the bottom of the coil. That is standing wave current and it is NOT flowing. It is just standing still as explained by Hecht. > These vary together in time according to cos(wt). It > is not possible to measure the "wrong kind" of current by mistake, > because there is only one kind. Sorry, you are wrong about that. A look at the equations while varying 'x' proves your statement is wrong. Please reference what Hecht said about those equations in another one of my postings. You have already admitted that there is more than one kind of current, e.g. DC Vs RF. It's time to admit that standing wave current and traveling wave current have different equations and therefore are different "kinds" of current. -- 73, Cecil http://www.qsl.net/w5dxp Article: 223023 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Coils and Transmission Lines. References: Message-ID: Date: Mon, 03 Apr 2006 00:48:31 GMT Ian White GM3SEK wrote: > I don't intend to - that quotation is perfectly correct. It means that > in a test-case situation where the lumped model *does* apply, the > distributed model will give EXACTLY the same results. Ian, you know nothing is "EXACTLY" the same. All you can say is that the two models give acceptably similar results within a certain range of accuracy. To paraphrase Roger Whittaker: "'EXACTLY' is for Children Spinning Daydreams". > This is the test case that I'm trying to make you apply, to check that > with a lumped-inductance load, your antenna theory predicts the correct > behaviour, namely no phase shift in the current through a lumped > inductance. :-) That's like proving there's no loss in a lossless transmission line, Ian. Please send me a 100 uH lumped inductance and I will run some tests on it and report back to you. What do you want to bet the lumped circuit model will be wrong? Some people have a problem with their model trying to dictate reality. You seem to have fallen into that trap. Allow me to raise my voice. THERE IS NO SUCH THING IN REALITY AS A LUMPED INDUCTANCE!!!! The lumped circuit model is an approximation to reality. It has been patched numerous times as situations came up that it could not handle. Sometimes it works and sometimes it doesn't work. Since the distributed network model is a superset of the lumped circuit model, if there is ever any disagreement between the two models, the distributed network model wins every time. The test is not whether the distributed network model yields the same results as the lumped circuit model. The test is whether the lumped circuit model yields the same results as the distributed network mode. That's what the argument is all about. The distributed network model is the GOLD standard. The lumped circuit model is just a pale approximation to reality. > There's no problem with the distributed circuit model. There's no > problem with the lumped circuit model as a subset of that. All the > problems are with your incorrect application of those models. That may be true, but we will never know until you (and others) recognize the difference between standing wave current and traveling wave current as explained in my other posting. But in case you missed it, here is a one wavelength dipole fed 1/4 WL from the right end. ///// is a 90 degree loading coil. ------A------B-/////-D-------------fp------------- The current at B is measured by an RF ammeter at one amp. The current at D is measured by a similar RF ammeter at zero amps. I can provide an EZNEC model if you like. How does your lumped circuit model explain those measured results? -- 73, Cecil http://www.qsl.net/w5dxp Article: 223024 of rec.radio.amateur.antenna From: "Marco Licetti" Subject: RF/microwaves over Fiberoptic cable??? Message-ID: Date: Mon, 03 Apr 2006 00:54:03 GMT I am not here to pester about own company - I do NOT work for this but just to share experience: For antenna remoting, etc RF-over-fiberoptic we found www.miteq.com is the best, somehwhat EXPENSIVE but tech specs are best in the world (noise, gain flatness, etc). As you know fiberoptic is the ONLY solution for LOSSLESS & SAFE transmitting RF over a long distance e.g. from antennas, on ship/aircraft, etc because first unlike Coax cable fiber doesn't suffer from excessive loss (you can have a 10-kilometer link no problem!), second it's hard to intercept (if you break fiber it iwll be notices, while Coax cable can be tapped in illegally), third it's immensely interference-immune, etc, etc. though mor eexpensive. That we found perfcect for Antenna remoting when facilities cannot be built near each antenna (antenna array), also for spying/military application fiber is safer than coax cble, and finally on aircrafts, etc you would prefer fiberoptic due to its immunity to interference (life-safety issues). So www.miteq.com I found by clicking on "components & assemblies" (NOT satellite comm)-->the clicked "fiberoptic products", they even posted datasheets and brochures there (maybe too much info!) Article: 223025 of rec.radio.amateur.antenna From: richardharrison@webtv.net (Richard Harrison) Subject: Re: Current through coils Date: Sun, 2 Apr 2006 19:11:30 -0600 Message-ID: <11762-44307642-861@storefull-3252.bay.webtv.net> References: <2sM63YaI$EMEFAeb@ifwtech.co.uk> Ian, GM3SEK wrote: 'There are several methods of finding current distribution." "I may be a fool, but I`n not the fool to be pitied because I disagreed with Terman. On page 893 of the 1955 edition of "Electronic and Radio Engineering" Terman writes: "An antenna can therefore be regarded as a resonant system with distributed constants. As a result, the impedance of an antenna behaves in much the same manner as does the impedance of a transmission line (see Sec. 4-7)." This is not news to many thread participants. Fig. 4-7 on page 96 shows an open-circuited transmission line. At the open circuit there is maximum voltage and zero current. Except for radiation and loss to heat, the typical standing-wave antenna would behave much the same as this ideal transmission line. Not only does Terman give voltage and current diagrams, he gives a phase diagram. It shows that whenever the voltage or current crosses the zero axis (changes sign) the phase angle changes abruptly by 180-degrees. Phase is unchanging between these inflection points. This agrees with what Cecil has said all along in this discussion. Best regards, Richard Harrison, KB5WZI Article: 223026 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Current through coils References: <85ydnUdYMN0xMbzZnZ2dnUVZ_vednZ2d@adelphia.com> <1223dvop83mkq9a@corp.supernews.com> <12244tdjaher025@corp.supernews.com> <1224i2p9j0tr33d@corp.supernews.com> <9oidndktkuKTQ7_ZnZ2dnUVZ_vudnZ2d@adelphia.com> <1227bed4qaf0t71@corp.supernews.com> <1144027110.027962.11830@e56g2000cwe.googlegroups.com> Message-ID: Date: Mon, 03 Apr 2006 01:31:24 GMT w8ji@akorn.net wrote: > If the loading coil is physically large and has a good amount of > displacement current flowing radially to space and objects around the > antenna compared to through current, the coil would have a noticable > difference in current at the bottom terminal and top terminal. How does one amp at the top and zero amps at the bottom grab you? Please see my other postings. > It's only when the coil becomes physically large and has appreciable > capacitive reactance to the outside world compared to the load > impedance that it starts to show significant transmission line effects. Which is certainly the case for a 75m bugcatcher coil. > Every bit of this is not difficult to understand if we really > understand how an antenna behaves and how a coil behaves. The only > source of wonderment and argument seems to come from people who want to > make the inductor behave differently in an antenna than it behaves in > other systems. The 75m bugcatcher coil certainly behaves differently mounted one foot above a GMC pickup ground plane than it behaves in free space. The question is: which is more common? A GMC pickup or free space? > There is no reason to assign > special properties to an inductor and make it behave differently in an > antenna than it does in other systems. There is no reason to assume an inductor behaves differently above a GMC truck ground plane than it behaves in free space??? Tom, would you please describe the free space that exists inside your head? -- 73, Cecil http://www.qsl.net/w5dxp Article: 223027 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Current through coils References: <2sM63YaI$EMEFAeb@ifwtech.co.uk> <11762-44307642-861@storefull-3252.bay.webtv.net> Message-ID: Date: Mon, 03 Apr 2006 01:38:46 GMT Richard Harrison wrote: > Not only does Terman give voltage and current diagrams, he gives a phase > diagram. It shows that whenever the voltage or current crosses the zero > axis (changes sign) the phase angle changes abruptly by 180-degrees. > Phase is unchanging between these inflection points. This agrees with > what Cecil has said all along in this discussion. Kraus agrees. Yet W7EL used that unchanging phase to measure the delay through a loading coil. What's wrong with that picture? Some people, who no doubt have recognized their technical errors, simply refuse to discuss the technical subjects. Ian, OTOH, seems open to discussing those topics so please don't be too hard on him. An honest person deserves respect whether he is right or wrong. -- 73, Cecil http://www.qsl.net/w5dxp Article: 223028 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: What is an EH antenna References: <1143908604.326393.313760@j33g2000cwa.googlegroups.com> <2yUXf.18997$B_1.11490@edtnps89> <1230fue8b8chkbf@corp.supernews.com> <1144027979.662007.152180@g10g2000cwb.googlegroups.com> Message-ID: Date: Mon, 03 Apr 2006 01:41:42 GMT w8ji@akorn.net wrote: > No matter what facts multiple independent sources submit, those who > have faith will ignore the facts. :-) That apparently includes individuals with faith in the lumped circuit model under conditions where it is known to fail. :-) -- 73, Cecil http://www.qsl.net/w5dxp Article: 223029 of rec.radio.amateur.antenna From: "David G. Nagel" Subject: Re: RF/microwaves over Fiberoptic cable??? Date: Sun, 02 Apr 2006 20:46:23 -0500 Message-ID: <1230vlo9u8mucdd@corp.supernews.com> References: Marco Licetti wrote: > I am not here to pester about own company - I do NOT work for this but just > to share experience: > For antenna remoting, etc RF-over-fiberoptic we found www.miteq.com is the > best, somehwhat EXPENSIVE but tech specs are best in the world (noise, gain > flatness, etc). As you know fiberoptic is the ONLY solution for LOSSLESS & > SAFE transmitting RF over a long distance e.g. from antennas, on > ship/aircraft, etc because first unlike Coax cable fiber doesn't suffer from > excessive loss (you can have a 10-kilometer link no problem!), second it's > hard to intercept (if you break fiber it iwll be notices, while Coax cable > can be tapped in illegally), third it's immensely interference-immune, etc, > etc. though mor eexpensive. > > That we found perfcect for Antenna remoting when facilities cannot be built > near each antenna (antenna array), also for spying/military application > fiber is safer than coax cble, and finally on aircrafts, etc you would > prefer fiberoptic due to its immunity to interference (life-safety issues). > So www.miteq.com I found by clicking on "components & assemblies" (NOT > satellite comm)-->the clicked "fiberoptic products", they even posted > datasheets and brochures there (maybe too much info!) > > > I'm a little confused here. Fiberoptic cables don't carry RF, they only transmit light. What I read in the advertising is a "bandwidth" of upto atleast 11Ghz. This is a data rate not a RF energy transmission capacity. Fiberoptic cable is made of "glass" which is nonconductive to RF energy. Can you expand on the subject. Dave Nagel Article: 223030 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Current through coils References: <2sM63YaI$EMEFAeb@ifwtech.co.uk> <11762-44307642-861@storefull-3252.bay.webtv.net> Message-ID: Date: Mon, 03 Apr 2006 01:58:37 GMT Cecil Moore wrote: > Some people, who no doubt have recognized their technical errors, > simply refuse to discuss the technical subjects. Ian, OTOH, seems > open to discussing those topics so please don't be too hard on him. > An honest person deserves respect whether he is right or wrong. In accordance with my goal of being honest, here is some ammunition for the other side of the argument. In Dr. Corum's IEEE paper he said regarding the Z0 of a loading coil: "It is worth noting that, for a helical anisotropic wave guide, the effective characteristic impedance is not merely a function of the geometrical configuration of the conductors (as it would be for lossless TEM coaxial cables and twin-lead transmission lines), but it is ALSO A FUNCTION OF THE EXCITATION FREQUENCY." I have been assuming that the Z0 of a loading coil didn't change much with frequency. Both Dr. Corum and EZNEC seem to disagree with that assumption. So, as is my practice, I am using the scientific method to adjust my concepts about that subject. I hope this proves that I am only interested in the technical facts which have not been proven one way or another as of this posting. -- 73, Cecil http://www.qsl.net/w5dxp Article: 223031 of rec.radio.amateur.antenna From: Bob Bob Subject: Re: RF/microwaves over Fiberoptic cable??? References: Message-ID: <3cc6g3-meh.ln1@p400bob.personal.cox.net> Date: Sun, 02 Apr 2006 21:03:14 -0500 Hi Marco Yes but its more of use in a commercial/military than amateur radio environment. I remember that certain cellular site installs I was involved in ran fiber from a the "main" RF TX/RX device to a remote location. The remote location simply had a broadband amplifier for the separate TX and RX. This was used in an underground railway station going out to maybe 3-4 locations. It was more cost effective doing it this way than by long coax runs at 900/1800MHz. It will be a cost/benefit tradeoff of whatever RF/SMOF/RF interface device you have to purchase vs the cost of coax vs fiber. This is something an amateur radio person isnt likely to do for his/her hobby. I also doubt whether it will be commercially viable for amateur radio manufacturers to include fiber interfacing. OBTW you can tap/intercept optical fibre . Cheers Bob W5/VK2YQA Marco Licetti wrote: > I am not here to pester about own company - I do NOT work for this but just > to share experience: Article: 223032 of rec.radio.amateur.antenna From: "Marco Licetti" References: <1230vlo9u8mucdd@corp.supernews.com> Subject: Re: RF/microwaves over Fiberoptic cable??? Message-ID: Date: Mon, 03 Apr 2006 02:36:54 GMT Huh? Listen person, it's easy: RF modulates laser at Tx, then at Rx light is demodulated into RF. Problem is few companies are able to offers specs Miteq offers i.e. gain ;lfatness/distortion, noise, etc. to [preserve original RF signal and 11GHz is not really a limit, they mentioned 18GHz can be built on individual basis (probably costs $18,000 heheheh) Article: 223033 of rec.radio.amateur.antenna From: "Marco Licetti" References: <3cc6g3-meh.ln1@p400bob.personal.cox.net> Subject: Re: RF/microwaves over Fiberoptic cable??? Message-ID: Date: Mon, 03 Apr 2006 02:38:43 GMT OK. Just one comment: intercepting fiberoptics is more complicated/costly than metal "wires" Article: 223034 of rec.radio.amateur.antenna From: "jimmiefender@bellsouth.net" References: Subject: Re: SWR Tells Me?? Message-ID: Date: Sun, 2 Apr 2006 22:45:06 -0400 "jimbo" wrote in message news:n8Odnbf6bInxW4PZRVn-qQ@comcast.com... > OK, I have a new 2 meter j-pole antenna installed in my 3rd floor attic. I > have 50 feet of LMR240 coax running to the basement. I measure SWR at the > following frequencies on simplex. > > 144.2 2.5 > 145.2 2.4 > 146.2 2.3 > 147.2 1.9 > 147.9 1.7 > > Can I conclude that the antenna is electrically short for the 2 meter > band? > > Thanks for any insight, jimbo My experience has been that J poles can be fairly fiddely things to really get right. By right I mean SWR nearly 1:1 right in the middle of the band. However if you are not so concerned with 'rightness' they can be a quick cheap way to get on the air and I have nothing against that. I doubt if putting the antenna up in the attic help much more than having it in the room near your position. I have one I travel with made up like a pole lamp(remember these >from the 50s,60s). Could be too short, Phasing section may be too long. Maybe both. Feedpoint is probably in the wrong place. Balun couldnt hurt. Add about 10 inches of coax to the feedline and check SWR again if it changes significantly you need the balun. Not something fun to play with in the attic. Article: 223035 of rec.radio.amateur.antenna From: "Yuri Blanarovich" References: <1143142526.021154.67050@e56g2000cwe.googlegroups.com> Subject: Re: Current across the antenna loading coil - from scratch Message-ID: Date: Sun, 2 Apr 2006 22:54:10 -0400 wrote in message news:1143142526.021154.67050@e56g2000cwe.googlegroups.com... > This thread belongs back in the original place, so it flows in context. > Sorry I had to take a break and lost the place in original place, so lets try to continue here, we are trying to go step by step. > Yuri Blanarovich wrote: >> OK, I have been accused of being wrong, claiming that current across the >> antenna loading coil is or can be different at its ends. > > No one said that. > So what is it then you claiming being equal. >> I and "my camp" say that we are seeing somewhere 40 to 60 % less current >> at >> the top of the coil, than at the bottom, in other words, significant or >> noticeable drop. > > Quit trying to make it a gang war. It is antenna theory, not a bar > room brawl with a bunch of drunks. > No gang wars intended, just trying to underline that there are two major supporting "camps" claiming that the current has to be equal, or is appreciably different. >> W8JI and "his camp" are claiming it can't be so, current through the coil >> has to be the same or almost the same, with no significant drop across >> the >> loading coil. > > I have no camp. You are lifting what I say out of context and deleting > important things. > > What I say, over and over again, is I can build an inductor in a short > mobile antenna that has essentially equal currents at each end. A > compact loading coil of good design has this type of performance. > I can do that too and do not deny it. > The current taper across the inductor is not tied to the number of > "electrical degrees" the inductor "replaces". It is tied to the > distributed capaciatnce of the coil to the outside world in comparison > to the termination impedance at the upper end of the coil. > That too, but that seems to be minor cause. Lets do it step by step. I will skip agreements so far. >> The current distrubution on said (full size) vertical is one quarter of >> the >> wave of 360 deg. which would make it 90 degrees. Max current is at the >> base >> and then diminishes towards the tip in the cosine function down to zero. >> Voltage distribution is just opposite, min at the base, feed point and >> max >> at the tip. EZNEC modeling shows that to be the case too. >> Is that right or wrong? > > Right. Although the distributed capacitance can change the shape. > It can change the amplitude, but not the shape of the current distribution curve, that is the maximum is at the feed point (zero reactance - resonance) and zero at the tips and follows cosine function. >> If we stick them end to end and turn horizontal, we get dipole, which >> then >> would be 180 deg. "long" or "180 degrees resonant". >> If not, what is the right way? > > Right. > >> If I insert the coil, say about 2/3 up (at 5 ft. from the bottom) the >> shortened vertical, I make the coil size, (inductance, phys. dimensions) >> such that my vertical will shrink in size to 8 ft tall and will resonate >> at >> 7.87 MHz. >> I learned from the good antenna books that this is still 90 electrical >> "resonant" degrees. >> Maximum of current is at the feed point, minimum or zero at the tip. > > What "good book"? It would help to see the context. > Say ARRL Antenna Book, 20th edition, page 16-7, Fig 10 Shows lengths h1 and h2 expressed as 15 deg. eaach. > None of my engineering books use electrical degrees except to describe > overall antenna height or length. > But that relates to describing the antenna properties in relation to resonant frequency for that particular radiator. > They might say "60 degree top loaded resonant radiator" but they don't > say "60 degree tall radiator 90 degree resonant". > If you stick the coil at the base in series with radiator and bring it to resonance (zero reactance at the frequency of interest) what "degree resonant" will than radiator become, if not 90? ("Measured" from the feed point, through the coil and then straight radiator.) > There might be a correct context, but I can't think of one off hand. So > I need an example from a textbook. > >> If you stick those verticals (resonant) end to end and horizontal, you >> get >> shortened dipole, with current distribution equal to 180 degrees or half >> wave. Max current at the feed point, minima or zero at the tips. >> (RESONANT >> radiator) > > The current distribution would not be the same as a half wave, becuase > the antenna is not 1/2 wave long. > Well, is 180 degrees half wavelength or not? Is the current maximum at the feedpoint (center) and zero at the end, or not? The current distribution is not the same, but is exhibiting properties of resonant half wave dipole with current max at the center and zero at the tips. The shape is not the smooth continuous cosine curve as in straight dipole, but affected by the loading coils (drops) in their place (subject of disagreement). >> Can we describe "pieces" or segments of the radiator as having >> proportional >> amount of degrees corresponding to their physical length, when excited >> with >> particular frequency? > > Yes. It works fine for length. It does NOT work for loading inductors, > it does not work for short antennas which have anything form a uniform > distribution to triangular distribution, or any mix between including > curves of various slopes. > Why not? What happens to cosine current distribution curve when we insert the loading element (inductance, coil, loading stub, resistance) in the radiator? What formula applies to get the uniform or triangular distribution? Can you show some mathematics? So we have resonant standing wave element, that has current max at the feedpoint and zero at the tip, which gives us 90 degree (or 180 with dipole) or quarter wave distribution from the base to the tip. (reality) We can express the straight pieces of radiator in degrees, but not the coiled up piece that the wave has to go through? The "uniform" and "triangular" distribution was used for approximation or simplification of showing the current distribution in short loaded radiators, while they are in reality segments of the cosine curve belonging to length of the straight portions of the radiator. EZNEC shows that, when you magnify the curve you can see there are no uniforms or triangles but a cosine curve. > A 30 degree tall antenna with base loading simply has power factor > correction at the base, provided the inductor is not a significant > fraction of a wavelength long. It is a 30 degree base loaded radiator, > not a 90 degree antenna. And the inductor is not 60 degrees long. > We are not talking here about base loaded radiator. No detours please. So how many electrical degrees has the quarter wave resonant radiator that is loaded with loading coil (or stub) about 2/3 way up and is say 30 deg. physical "length" to make it resonant? > 73 Tom > 73 Yuri, K3BU Article: 223036 of rec.radio.amateur.antenna From: "Yuri Blanarovich" References: <12244tdjaher025@corp.supernews.com> <1224i2p9j0tr33d@corp.supernews.com> <9oidndktkuKTQ7_ZnZ2dnUVZ_vudnZ2d@adelphia.com> <1227bed4qaf0t71@corp.supernews.com> <60u032hnsq7ll9nai6pmil0c66d3el8emd@4ax.com> Subject: Re: Current through coils Message-ID: Date: Sun, 2 Apr 2006 23:24:05 -0400 "Richard Clark" wrote > If it doesn't count for much, > or it has no relevancy, then say so and by all means drop it. I think it is significant, not as much in "crummy" mobile vertical, as in antenna systems with loaded, shortened elements. I saw significant improvement in performance when replacing loading stubs in say KLM 3 el. 80m Yagi with coils. Performance and pattern improved significantly. If you stick wrong values in modeling program, the error will get only magnified. That's why this "bothers" me. I trust what W9UCW measured, and I want to do it myself, just to put the heated subject to rest with proper conclusions. Yuri Article: 223037 of rec.radio.amateur.antenna From: Bob Bob Subject: Re: RF/microwaves over Fiberoptic cable??? References: <3cc6g3-meh.ln1@p400bob.personal.cox.net> Message-ID: Date: Sun, 02 Apr 2006 22:31:06 -0500 Not if you are in the business of spying! It takes a machine that can penetrate or couple to the fiber without damaging its throughput (much). I mean given that fiber splicing uses a pretty expensive machine itself I doubt am eavesdropping device would be much harder to manufacture... Your next big expense is to sort through the reams of data that pass through the link! Do you see it as being viable for amateur radio hobbyists or was your post for general technical interest only? Perhaps I am missing some possibilities here.. Cheers Bob Marco Licetti wrote: > OK. Just one comment: intercepting fiberoptics is more complicated/costly > than metal "wires" > > Article: 223038 of rec.radio.amateur.antenna From: richardharrison@webtv.net (Richard Harrison) Subject: Re: Current through coils Date: Mon, 3 Apr 2006 00:09:17 -0600 Message-ID: <3357-4430BC0D-178@storefull-3258.bay.webtv.net> References: <1144037197.028238.241940@u72g2000cwu.googlegroups.com> Tom, K7ITM wrote: "Given any volume, say a volume containing a Texas Bugcatcher coil and the air inside and immediately around it, if you push more electrons in than come out_for_ANY_arbitrarily_short_time_period_, you have changed the net charge in that volume;---." No. This is not charging a capacitor or a battery. Energy stored in an antenna system is in constant motion. Power delivered by the transmitter is neadly the same as that used by the load, (the antenna), plus that consumed by losses. Power is simply the in-phase volts times amps. It can have any impedance which is the ratio of in-phase volts to amps. Z in the general case can include reactance plus resistance and can give the apparent power. It is the ratio of volts to amps without regard to phase. The coil which has a great difference between the current at its ends most likely simply has different impedances at its ends. The power is nearly the same at both ends of the coil but the voltage to current ratios are different. Varying impredance along the RF path is a product of the interference between the incident and reflected waves. A standing-wave antenna typically has an open-circuit at its end or ends. The RF has no other option but to be returned toward the sender and make standing waves. The large number of possible incident and reflected wave combinatioms makes it very likely that the current at opposite ends of a coil inserted in the antenna system will be unequal. It`s the power in and out of a coil in an antenna system that`s likely to be nearly equal at both ends. Best regards, Richard Harrison, KB5WZI Article: 223039 of rec.radio.amateur.antenna From: Bob Subject: Re: RF/microwaves over Fiberoptic cable??? References: Message-ID: Date: Mon, 03 Apr 2006 06:16:59 GMT I fiber many channels of RF in the course of my job and found Miteq a bit over rated and extra pricey. I’ll stick with ORTEL for reliable RF/Fiber links. Bob Marco Licetti wrote: > I am not here to pester about own company - I do NOT work for this but just > to share experience: > For antenna remoting, etc RF-over-fiberoptic we found www.miteq.com is the > best, somehwhat EXPENSIVE but tech specs are best in the world (noise, gain > flatness, etc). As you know fiberoptic is the ONLY solution for LOSSLESS & > SAFE transmitting RF over a long distance e.g. from antennas, on > ship/aircraft, etc because first unlike Coax cable fiber doesn't suffer from > excessive loss (you can have a 10-kilometer link no problem!), second it's > hard to intercept (if you break fiber it iwll be notices, while Coax cable > can be tapped in illegally), third it's immensely interference-immune, etc, > etc. though mor eexpensive. > > That we found perfcect for Antenna remoting when facilities cannot be built > near each antenna (antenna array), also for spying/military application > fiber is safer than coax cble, and finally on aircrafts, etc you would > prefer fiberoptic due to its immunity to interference (life-safety issues). > So www.miteq.com I found by clicking on "components & assemblies" (NOT > satellite comm)-->the clicked "fiberoptic products", they even posted > datasheets and brochures there (maybe too much info!) > > > Article: 223040 of rec.radio.amateur.antenna From: "Sal M. Onella" References: <1143969836.641578.171360@g10g2000cwb.googlegroups.com> Subject: Re: how to reduce ghost from a wall mounted uhf antenna Message-ID: <7b3Yf.1925$I%6.385@fed1read12> Date: Sun, 2 Apr 2006 23:23:00 -0700 wrote in message news:1143969836.641578.171360@g10g2000cwb.googlegroups.com... > i have a uhf tv antenna on my balcony. i am getting ghosting. > > i think the ghosting is from signals bouncing off the balcony wall and > hitting the antenna a second time. > > apart from building a 100' tower to raise my antenna into the open sky, > is there any way to keep the wall from reflecting ? can i put some sort > of foil behind the antenna to block it out ?or cover the wall with some > non reflective material? > > thx > Try a twin-bowtie antenna with a screen behind it. (They're intended for indoor use, so the weather outside may eat it up.) Any complex antenna -- something beyond a loop or bow-tie antenna -- will discriminate against ghosts. Depending on where the transmitter is, all your signals may be ghosts. That is, you're receiving all your signals by reflections off SOMETHING and you need to pick the cleanest one, as another poster said. This sort of "picking" is best attempted with a big, fancy UHF antenna.. Good luck. Article: 223041 of rec.radio.amateur.antenna From: "Mike Coombes" References: <1144037197.028238.241940@u72g2000cwu.googlegroups.com> <3357-4430BC0D-178@storefull-3258.bay.webtv.net> <1144051302.246237.78830@e56g2000cwe.googlegroups.com> Subject: Re: Current through coils Date: Mon, 3 Apr 2006 19:00:14 +0800 Message-ID: <44310045$0$2110$5a62ac22@per-qv1-newsreader-01.iinet.net.au> I don't understand what you are all on about, but, I side with K7ITM "K7ITM" wrote in message Regards Mike. news:1144051302.246237.78830@e56g2000cwe.googlegroups.com... > Richard H wrote, > > "Tom, K7ITM wrote: > > "Given any volume, say a volume containing a Texas Bugcatcher coil and > the air inside and immediately around it, if you push more electrons in > than come out_for_ANY_arbitrarily_short_time_period_, you have changed > the net charge in that volume;---." > > No. ..." > > OK, I'm going to repeat it once more: > > If you shove more electrons into ANY volume than you remove, you have > changed the charge within that volume. I do NOT care WHAT is in that > volume. Current is the rate that charge is flowing past a point on a > conductor. If the only way I have of getting charge into and out of a > particular volume is through two wires, then the difference in current > at every instant in time represents the time rate of change of charge > within that volume. That is true INDEPENDENT of whether it is in an > antenna, and it is INDEPENDENT of what's inside that volume. > > In fact, energy around an antenna is stored in electric and magnetic > fields. These are inexorably linked to inductance along the conductors > composing the antenna, and capacitance from these conductors to > themselves and to any counterpoise or ground plane which may be part of > the antenna--anything where electric field lines terminate. The charge > per unit length along an antenna wire, be it resonant or not, be it a > "standing wave" or a "travelling wave" antenna, varies with time. If > it did not, then the current would necessarily be identical along the > whole wire all the time. > > This all gets back to very basic definitions of charge, and current as > the rate of flow of charge. It's all consistent with Maxwell, Gauss, > Faraday, etc. and with waves both standing and travelling, and with > "impredances" and all the rest. > > It's just amazing to me that some of you are fighting so hard against > the very thing which has a chance of unifying your "wave" model with > the realities of the electric and magnetic fields, and the associated > capacitance and inductance along the antenna--indeed, along the wire > itself, and not just along the coil. > > Without capacitance, there can be NO difference in current anywhere > along the wire, because there is simply no place to put the charge > implied by differing currents at differing locations. With capacitance > and inductance, everything works just as it's supposed to--just as it > DOES--and a properly developed wave theory will analyze it just fine, > if that's your cup of tea. > > Cheers, > Tom > Article: 223042 of rec.radio.amateur.antenna From: "Richard Fry" References: <1143142526.021154.67050@e56g2000cwe.googlegroups.com> <0hf13258667d7d0m648bf6rbgm6ecrj2sl@4ax.com> Subject: Re: Current across the antenna loading coil - from scratch Date: Mon, 3 Apr 2006 07:15:17 -0500 Message-ID: <44311110_2@newsfeed.slurp.net> "Richard Clark" wrote > This must be a convention that is particular to only a very few > Hams. The FCC database describes AM antennas in both > electrical and physical height as follows. .<>... it would seem > odd to step out of this expectation to change to calling all > antennas 90° simply because they resonate. _____________ The FCC data cited does not include the reduced velocity of propagation along the radiator -- which means that an FCC "90 degree" radiator is not resonant, it has some inductive reactance. A network is used at the radiator feedpoint to transform the complex impedance there to properly match the transmission line. That "90 degree" radiator would need to be shortened by several percent in order to be self-resonant. Kraus (3rd Ed, p 182) shows a feedpoint Z of 73 + j42.5 ohms for a thin-wire, linear dipole that is a physical 1/2-wavelength, and that self-resonance occurs at a length a few percent shorter, when the radiation resistance drops to about 65 ohms. An unloaded 1/4-wave MW broadcast monopole working against the typical broadcast radial ground system has about 1/2 the impedance that Kraus shows for a dipole in free space. RF Article: 223043 of rec.radio.amateur.antenna From: "Yuri Blanarovich" References: <1224i2p9j0tr33d@corp.supernews.com> <9oidndktkuKTQ7_ZnZ2dnUVZ_vudnZ2d@adelphia.com> <1227bed4qaf0t71@corp.supernews.com> <60u032hnsq7ll9nai6pmil0c66d3el8emd@4ax.com> Subject: Re: Current through coils Message-ID: Date: Mon, 3 Apr 2006 09:35:16 -0400 "Richard Clark" wrote > Hi Yuri, > > This is a most ambiguous "bothering" in that you haven't put any > quantification to what the "error" leads to. No one can possibly > expect perfection, and ±20% is possibly the best accuracy most hams > can expect in measurement. We have all already identified that the > "error" stemmed from an inappropriate application of lumped inductance > in the place of a helix in modeling. > > This begs the question: "What's all the fuss over? What's to be > proven? and How do we know when it has BEEN proven?" > > 73's > Richard Clark, KB7QHC I think we are striving to improve our accuracy and reflection of reality in modeling antennas. We know that efficiency is proportional to the area under the current curve along the radiator. The "fatter" the curve, the better. This has been confirmed by the experimental measurements by varying position of the loading coil along the radiator and use of top hats. If the modeling program starts with wrong assumption (as we have seen using lumped inductance) and one uses multiple elements, like in vertical arrays or Yagis, then the results get skewed and we get wrong "recipe" for the antenna design. The biggest benefit would be in properly optimizing antenna design for the best rejection, F/B, cleanest pattern, which is more critical than just optimizing for max gain. Especially loaded arrays for low bands would benefit most. One could get good indication by comparing say 3 el loaded Yagi design with lumped inductance vs. loading stubs or solenoid model. Unfortunately, or fortunately, I am not retired, nor making living from the RF stuff and my time is limited to be working full time on this. My interest is to maximize the station and antenna design for contesting so I can try to cream some records. So far, it looks to me that this exercise is worthwhile if we can improve the accuracy of modeling and our understanding of the phenomena. Looks like lots of antennas would be damaged by the Midwest tornados, the ugly WX is heading our way. 73 Yuri, K3BU Article: 223044 of rec.radio.amateur.antenna From: "John Passaneau" Subject: Re: .pcb and .sch layout files help Date: Mon, 3 Apr 2006 09:36:58 -0400 Message-ID: References: <1143861236.631465.287540@i39g2000cwa.googlegroups.com> <1143867483.327888.317680@i40g2000cwc.googlegroups.com> He's right, but to answer your question, you most likely can't. It's my experience that even though these programs use the same extension, (sch,pcb) they are not in the same format. It's not like the extension .TXT which most anything can read these are propitiatory. If these were high end cad programs there might me translators available but not these lower level programs. -- John Passaneau Penn State University Physics Dept. jxp16@psu.edu "K7ITM" wrote in message news:1143867483.327888.317680@i40g2000cwc.googlegroups.com... > You'll probably have better luck posting in an electronics CAD group, > or even an electronics design group. A bonus is that you won't get > people here upset because you're posting something so far off an > "antennas" topic. > Article: 223045 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Coils and Transmission Lines. References: Message-ID: Date: Mon, 03 Apr 2006 14:04:00 GMT Ian White GM3SEK wrote: > Reality is not on trial here. We are examining your model which is > attempting to describe reality. In a test case where the loading is > DEFINED to be lumped inductance only, agreement with the lumped-circuit > model must be mathematically EXACT. The distributed network model *does agree EXACTLY* since the forward current phasor and reflected current phasor add up to the same magnitude and phase at both ends of the coil. The forward current is the same magnitude and phase at both ends of the coil and the reflected current is the same magnitude and phase at both ends of the coil. So their sums are trivially identical at both ends of the coil. Since I'm sure you know that already, your posting seems to me to be a diversion. What you say is true, but is already trivial common knowledge. > If one model is a true subset of the other, then as we come closer and > closer to the idealized test case, all the extra terms in the bigger > model will tend to zero leaving only the subset model. In the limit, the > agreement is indeed exact. And the agreement is indeed exact. Both models agree up to the point where the lumped-circuit model starts to fail. > You have put yourself in a position where you do need to understand > scientific logic in some detail, and follow the rules that logic lays > down... but you don't. Please don't engage in mind fornication. It is possible that you are the one failing to follow the scientific method. -- 73, Cecil http://www.qsl.net/w5dxp Article: 223046 of rec.radio.amateur.antenna From: richardharrison@webtv.net (Richard Harrison) Subject: Re: Current through coils Date: Mon, 3 Apr 2006 08:05:40 -0600 Message-ID: <11783-44312BB4-911@storefull-3254.bay.webtv.net> References: <1144051302.246237.78830@e56g2000cwe.googlegroups.com> Tom, K7ITM wrote: "OK. I`m going to repeat it once more." It is still irrelevant. The question is: Does an antenna have a different current at the two ends of an inserted coil? Anyone interested in antennas should have access to Kraus, 3rd edition, "Antennas". On page 824 is Figure 23-21. Item (a) is a dipole with traps (only 2 terminals) for 2-frequency operation, 1st and 2nd resonances are the purpose of the traps. At F2, current outboard of the traps is practically zero. At F1, the impedance of the traps still make impedance bumps but the current outboard of the trap ends, though substatially different from that inboard, is enough to allow the dipole to resonate. At F1 and F2, current at both ends of the coils are substantially different. You probably would put them in a box with only 2 terminals. Pity the fool who argues with Kraus! Best regards, Richard Harrison, KB5WZI Article: 223047 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Current across the antenna loading coil - from scratch References: <1143142526.021154.67050@e56g2000cwe.googlegroups.com> <1144062834.591149.121920@v46g2000cwv.googlegroups.com> Message-ID: <69aYf.63812$Jd.56966@newssvr25.news.prodigy.net> Date: Mon, 03 Apr 2006 14:18:42 GMT w8ji@akorn.net wrote: > In a loading coil with very small distributed capaciatnce to the > outside world compared to termination impedance, current has to be > equal. Phase shift in current at each end has to be nearly zero. That is a false statement and is at the root of the misconceptions. Standing wave current does not have to be equal. I have shown how current at the bottom of the coil can be zero while the current at the top of the coil is one amp. Do you think the coil is sucking that one amp sideways from somewhere else through its distributed capacitance? There's no magic involved, just simple, easy to understand, distributed network theory. The current at the top and bottom of a coil depends upon where it is placed in the standing wave environment. Standing wave current doesn't flow. It is the underlying forward current and reflected current that is doing the flowing. Such is obvious from the equations. Hecht, in "Optics", has the best description of standing waves that I have ever read. He says: "[Equation (7.30)] is the equation for a STANDING or STATIONARY WAVE. Its profile does not move through space. ... [Its phase] doesn't rotate at all, and the resultant wave it represents doesn't progress through space - it's a standing wave." Translating into RF language. Func(kx)*Func(wt) is the equation for a STANDING or STATIONARY WAVE, i.e. the standing wave is stationary. Its magnitude does not move through the wire. Its phase doesn't rotate at all, and the resultant standing wave it represents doesn't progress through a wire or through a coil - it's a standing wave. Until everyone takes time to understand the nature of standing waves, people will keep making the same tired mistake over and over. -- 73, Cecil http://www.qsl.net/w5dxp Article: 223048 of rec.radio.amateur.antenna From: "Yuri Blanarovich" References: <1143142526.021154.67050@e56g2000cwe.googlegroups.com> <0hf13258667d7d0m648bf6rbgm6ecrj2sl@4ax.com> Subject: Re: Current across the antenna loading coil - from scratch Message-ID: <5qaYf.6$qO.0@fe10.lga> Date: Mon, 3 Apr 2006 10:36:45 -0400 "Richard Clark" wrote > Hi Yuri, > > This must be a convention that is particular to only a very few Hams. > The FCC database describes AM antennas in both electrical and physical > height as follows. > > WGOP 80.00° tall 125.2 meters tall 540 kHz > WWCS 63.50° tall 98.8 meters tall 540 kHz > WFTD 79.00° tall 64.0 meters tall 1080 kHz > KYMN 118.60° tall 92.3 meters tall 1080 kHz > WWLV 90.00° tall 47.2 meters tall 1620 kHz > WTAW 204.00° tall 106.7 meters tall 1620 kHz > > There may be some discrepancy, but it certainly looks like antenna > specification is by the electrical equivalent of the physical height > (and whatever l/d fudging) and with only one happening to be 90°. > > Further, given most references (for professionals) is aimed at a > common specification that is largely driven by this agency, it would > seem odd to step out of this expectation to change to calling all > antennas 90° simply because they resonate. > > re: > http://www.fcc.gov/mb/audio/amq.html > > 73's > Richard Clark, KB7QHC That's fine, no argument there. But do you agree that there are towers of X height in meters and when "naked" having Y electrical degrees, loaded with top hat of size S, not changing the physical height, but adding Z degrees. So the top hat adds some degrees to the tower. Is it such ham radio crime to say that coil can do that too, if it is inserted within the radiator? We use imaginary lumped inductor to understand coils better, but we can not use electrical degrees to 'splain the behavior of coiled antenna wire? I think we are progressing into antenna modeling and design and I see nothing wrong with using degrees to describe electrical properties (resonance) of the loaded radiator. 73 Yuri, K3BU actually WWLV 90.00° tall 47.2 meters tall 1620 kHz should show closer to 92 deg. and assuming that they use fatter tower, even more. Article: 223049 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Current through coils References: <85ydnUdYMN0xMbzZnZ2dnUVZ_vednZ2d@adelphia.com> <1223dvop83mkq9a@corp.supernews.com> <12244tdjaher025@corp.supernews.com> <1224i2p9j0tr33d@corp.supernews.com> <9oidndktkuKTQ7_ZnZ2dnUVZ_vudnZ2d@adelphia.com> <1227bed4qaf0t71@corp.supernews.com> <1144027110.027962.11830@e56g2000cwe.googlegroups.com> <1144037197.028238.241940@u72g2000cwu.googlegroups.com> Message-ID: Date: Mon, 03 Apr 2006 14:36:25 GMT K7ITM wrote: > And I still say that your other postings > before that were saying you believed that there was NO capacitance to > the outside world. It was the message they sent to me, loud and clear. I may have said that a pure lumped inductance has no capacitance to the outside world and that is true by definition. Perhaps that is what you are remembering. Anyone would be crazy to assert that a real world coil has no capacitance to the outside world. What I said is that capacitance to the outside world is often a secondary effect compared to the primary effect of superposing forward and reflected currents. > Given any volume, say a volume containing a Texas Bugcatcher coil and > the air inside and immediately around it, if you push more electrons in > than come out _for_ANY_abritrarily_short_time_period_, you have changed > the net charge in that volume; if you pull out more electrons than go > in, you have changed the net charge in that volume. But that is not happening. Standing wave current doesn't flow. It just stands there. How many times do I have to repeat the following. Assume the forward current is one amp and the reflected current is one amp. The standing wave current is the phasor sum of those two currents. One amp of forward current is flowing into the coil and one amp of forward current is flowing out of the coil. There is ZERO net storage of charge associated with the forward current. One amp of reflected current is flowing into the coil and one amp of reflected current is flowing out of the coil. There is ZERO net storage of charge associated with the reflected current. Since these two currents are the only currents, there is ZERO net storage of charge in the coil. The magnitude of the standing wave current is irrelevant. The forward current at the bottom of the coil is one amp at zero deg. The reflected current at the bottom of the coil is one amp at 180 deg. Their phasor sum, the standing wave current, is zero. The forward current at the top of the coil is 0.5 amp at -90 deg. The reflected current at the top of the coil is 0.5 amp at -90 deg. Their phasor sum, the standing wave current, is 1.0 amp at -90 deg. There's no net storage of charge in the coil, zero amps at the bottom of the coil, and one amp at the top. That proves that standing wave current doesn't flow, exactly as its equation says it doesn't flow, exactly as Hecht, in "Optics", says a standing wave "doesn't move through space". The rest of your posting is irrelevant since it just repeats the same old misconception that standing wave current flows. -- 73, Cecil http://www.qsl.net/w5dxp Article: 223050 of rec.radio.amateur.antenna From: "Yuri Blanarovich" References: <1144051302.246237.78830@e56g2000cwe.googlegroups.com> <11783-44312BB4-911@storefull-3254.bay.webtv.net> Subject: Re: Current through coils Message-ID: Date: Mon, 3 Apr 2006 10:41:49 -0400 "Richard Harrison" wrote > At F1 and F2, current at both ends of the coils are substantially > different. You probably would put them in a box with only 2 terminals. > Pity the fool who argues with Kraus! > > Best regards, Richard Harrison, KB5WZI > yea, but, but, but..... (the "equal current choir" :-) Thanks Richard! Yuri, K3BU Article: 223051 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Current through coils References: <1144037197.028238.241940@u72g2000cwu.googlegroups.com> <3357-4430BC0D-178@storefull-3258.bay.webtv.net> Message-ID: Date: Mon, 03 Apr 2006 14:44:36 GMT Richard Harrison wrote: > The coil which has a great difference between the current at its ends > most likely simply has different impedances at its ends. The power is > nearly the same at both ends of the coil but the voltage to current > ratios are different. Consider a 1/4WL open-circuit stub. The impedance at the open is very high and the current is zero. The impedance at the mouth of the stub is very low and the current is at a maximum. Exactly the same thing happens with a coil at the self-resonant frequency. The standing wave current at each end of a coil installed in a standing wave antenna depends upon its position in the antenna. To paraphrase Hecht, standing wave current "doesn't progress through a wire - it's a standing wave." -- 73, Cecil http://www.qsl.net/w5dxp Article: 223052 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Current through coils References: <1144037197.028238.241940@u72g2000cwu.googlegroups.com> <3357-4430BC0D-178@storefull-3258.bay.webtv.net> <1144051302.246237.78830@e56g2000cwe.googlegroups.com> Message-ID: Date: Mon, 03 Apr 2006 14:55:40 GMT K7ITM wrote: > If you shove more electrons into ANY volume than you remove, you have > changed the charge within that volume. That is true but having zero standing wave amps at one end of a coil and one standing wave amp at the other end doesn't mean the charge is changing. If the forward current is the same magnitude at both ends of the coil, there's no change in charge. If the reflected current is the same magnitude at both ends of the coil there's no change in charge. The standing wave current is the sum of those two phasors. That sum is what is fooling you. Please pay attention to Hecht, in "Optics". The standing wave current profile does not move through the wire just as the standing wave light profile does not move through space. Standing wave current doesn't progress through a wire just as standing wave light doesn't progress through space. -- 73, Cecil http://www.qsl.net/w5dxp Article: 223053 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Current through coils References: <1144037197.028238.241940@u72g2000cwu.googlegroups.com> <3357-4430BC0D-178@storefull-3258.bay.webtv.net> <1144051302.246237.78830@e56g2000cwe.googlegroups.com> <44310045$0$2110$5a62ac22@per-qv1-newsreader-01.iinet.net.au> Message-ID: Date: Mon, 03 Apr 2006 14:59:55 GMT Mike Coombes wrote: > I don't understand what you are all on about, but, I side with K7ITM > "K7ITM" wrote in message > Regards Mike. 1. If the magnitude of the forward current is the same at both ends of the coil, there is no net storage of charge. 2. If the magnitude of the reflected current is the same at both ends of the coil, there is no net storage of charge. These conditions satisfies K7ITM's requirements. But he is being fooled by the sum of the two above currents which is meaningless to net charge storage. Statements 1 and 2, above, already prove there is no net storage of charge. Looking at the standing wave current is meaningless after that technical fact. -- 73, Cecil http://www.qsl.net/w5dxp Article: 223054 of rec.radio.amateur.antenna From: "jimmiefender@bellsouth.net" References: <1143908604.326393.313760@j33g2000cwa.googlegroups.com> <2yUXf.18997$B_1.11490@edtnps89> Subject: Re: What is an EH antenna Message-ID: Date: Mon, 3 Apr 2006 00:14:33 -0400 "Frank's" wrote in message news:2yUXf.18997$B_1.11490@edtnps89... >> Recently heard about EH antennas and have done some research into them >> including reading some articles in this newsgroup. It is begining ti >> sound very much like my friends homemade FM/TV antenna. My friend being >> short on money fastened an old bicycle rim to a piece of galvanized >> pipe( axel stuck in the pipe) Feedline was connected from the center o >> the wheel to a point on the outer rim. I had repeated told my friend >> that something like this would never work and he demonstrated to me >> that it did.. I theink the EH antenna is a lot like this old wheel, >> just about anything placed on a mast with work to some degree. In this >> case a very poor antenna allowed my friend to receive 2 TV stations and >> 4 or 5 FM radio stations. This was a vast improvement over the 0 tv and >> Fm stations he was receving before putting up his "antenna" Would it be >> appropriate to say that an EH antenna is more like a coupler that >> utilises the antenna support structure(tower/mast) and feedline as the >> radiating elements of the antenna?. > > I think the EH is the same idea as the CFA; in which case the following > paper > says it all: http://www.fi.uba.ar/materias/6654/download/CFAantenna.pdf. > > It is hard to imagine going to these lengths to debunk nonsense, but I > guess > it is the only way. > > Frank > I have to admit that at one time I too thought a viable antenna could me made from lumped values of inductance and capacitance. I was about 12 or 13 at the time. I am also thinking my analogy with the bicycle rim antenna may not be so far off. LOL Article: 223055 of rec.radio.amateur.antenna From: "Tom Donaly" Subject: Re: Coils and Transmission Lines. References: <3gSXf.63583$Jd.40227@newssvr25.news.prodigy.net> Message-ID: Date: Mon, 03 Apr 2006 16:34:00 GMT Cecil Moore wrote: > Tom Donaly wrote: > >> Whatever. I'd still like to see his derivations. > > > "Optics", by Hecht, 4th edition, page 289. > > The intensity of a light beam is associated with the E-field > so Hecht's equations are in relation to the E-field. > > Speaking of the light standing wave: "The composite > disturbance is then: > > E = Eo[sin(kt+wt) + sin(kt-wt)] > > Applying the indentity > > sin A + sin B = 2 sin 1/2(A+B)*cos 1/2(A-B) > > E(x,t) = 2*Eo*sin(kx)*cos(wt)" > > Hecht says the standing wave "profile does not move through > space". > > I have said the RF standing wave current profile does not move > through a wire. > > Hecht says the standing wave phasor "doesn't rotate at all, > and the resultant wave it represents doesn't progress through > space - it's a standing wave." > > I have said the same thing about the RF standing wave current > phasor. > > Hecht says the standing wave transfers zero net energy. I have > said the same thing about RF standing waves. If it's a solution to the wave equation it's o.k., Cecil, but Hecht is still not using the case where there is a phase difference between the two waves. If it isn't in the original equation it won't be in the final version since they're just two ways of saying the same thing. That's fine because it's the wrong equation anyway for what you want, which involves impedances and length, which you probably don't want to deal with because you're probably under the impression they're just virtual and not real, and so not worthy of inclusion in your theory. 73, Tom Donaly, KA6RUH Article: 223056 of rec.radio.amateur.antenna From: "Tom Donaly" Subject: Re: Current across the antenna loading coil - from scratch References: <1143142526.021154.67050@e56g2000cwe.googlegroups.com> <1144062834.591149.121920@v46g2000cwv.googlegroups.com> <69aYf.63812$Jd.56966@newssvr25.news.prodigy.net> Message-ID: Date: Mon, 03 Apr 2006 17:07:27 GMT Cecil Moore wrote: > w8ji@akorn.net wrote: > >> In a loading coil with very small distributed capaciatnce to the >> outside world compared to termination impedance, current has to be >> equal. Phase shift in current at each end has to be nearly zero. > > > That is a false statement and is at the root of the misconceptions. > Standing wave current does not have to be equal. I have shown how > current at the bottom of the coil can be zero while the current > at the top of the coil is one amp. Do you think the coil is sucking > that one amp sideways from somewhere else through its distributed > capacitance? There's no magic involved, just simple, easy to > understand, distributed network theory. The current at the top > and bottom of a coil depends upon where it is placed in the > standing wave environment. Standing wave current doesn't flow. > It is the underlying forward current and reflected current that > is doing the flowing. Such is obvious from the equations. > > Hecht, in "Optics", has the best description of standing waves > that I have ever read. He says: "[Equation (7.30)] is the equation > for a STANDING or STATIONARY WAVE. Its profile does not move > through space. ... [Its phase] doesn't rotate at all, and the > resultant wave it represents doesn't progress through space - > it's a standing wave." > > Translating into RF language. Func(kx)*Func(wt) is the equation > for a STANDING or STATIONARY WAVE, i.e. the standing wave is > stationary. Its magnitude does not move through the wire. Its > phase doesn't rotate at all, and the resultant standing wave > it represents doesn't progress through a wire or through a > coil - it's a standing wave. > > Until everyone takes time to understand the nature of standing > waves, people will keep making the same tired mistake over and > over. Hecht was talking about two opposing waves of the same phase and amplitude interfering with each other. You can't guarantee, in a real antenna, that the two waves do have the same phase and magnitude. 73, Tom Donaly, KA6RUH Article: 223057 of rec.radio.amateur.antenna Subject: Re: Any recomends on a Auto tuner From: Dave Oldridge References: <1143906989.915252.172060@z34g2000cwc.googlegroups.com> Message-ID: Date: Mon, 03 Apr 2006 17:12:30 GMT Cecil Moore wrote in news:WkEXf.50615$2O6.49474 @newssvr12.news.prodigy.com: > ml wrote: >> surprized that nobody mentioned the sgc tungers > > My SGC-230 will tune everything including no antenna > at all. I once forgot to install the coil and stinger > on my mobile antenna. The SGC-230 faithfully tuned the > three foot bottom section to resonance on 75m. :-) Yeah, my MFJ 993B does the same thing, but the coax losses will KILL your signal! -- Dave Oldridge+ ICQ 1800667 Article: 223058 of rec.radio.amateur.antenna From: "Tom Donaly" Subject: Re: Current through coils References: <2sM63YaI$EMEFAeb@ifwtech.co.uk> <11762-44307642-861@storefull-3252.bay.webtv.net> Message-ID: Date: Mon, 03 Apr 2006 17:17:12 GMT Cecil Moore wrote: > Richard Harrison wrote: > >> Not only does Terman give voltage and current diagrams, he gives a phase >> diagram. It shows that whenever the voltage or current crosses the zero >> axis (changes sign) the phase angle changes abruptly by 180-degrees. >> Phase is unchanging between these inflection points. This agrees with >> what Cecil has said all along in this discussion. > > > Kraus agrees. Yet W7EL used that unchanging phase to measure the > delay through a loading coil. What's wrong with that picture? > > Some people, who no doubt have recognized their technical errors, > simply refuse to discuss the technical subjects. Ian, OTOH, seems > open to discussing those topics so please don't be too hard on him. > An honest person deserves respect whether he is right or wrong. Cecil, since you always leave the phase information out of your version of the solution of the wave equation, I don't think Diogenes is going to be knocking on your door anytime soon, either. 73, Tom Donaly, KA6RUH Article: 223059 of rec.radio.amateur.antenna From: "Tom Donaly" Subject: Re: Current through coils References: <1144037197.028238.241940@u72g2000cwu.googlegroups.com> <3357-4430BC0D-178@storefull-3258.bay.webtv.net> <1144051302.246237.78830@e56g2000cwe.googlegroups.com> Message-ID: Date: Mon, 03 Apr 2006 17:38:51 GMT Cecil Moore wrote: > K7ITM wrote: > >> If you shove more electrons into ANY volume than you remove, you have >> changed the charge within that volume. > > > That is true but having zero standing wave amps at one end > of a coil and one standing wave amp at the other end doesn't > mean the charge is changing. > > If the forward current is the same magnitude at both ends > of the coil, there's no change in charge. > > If the reflected current is the same magnitude at both > ends of the coil there's no change in charge. > > The standing wave current is the sum of those two phasors. > That sum is what is fooling you. Please pay attention to > Hecht, in "Optics". > > The standing wave current profile does not move through > the wire just as the standing wave light profile does > not move through space. > > Standing wave current doesn't progress through a wire just > as standing wave light doesn't progress through space. It sure would be nice if were as simple as all that. We wouldn't need NEC to help us if it were. You're missing the point, Cecil, read Tom's post again, and meditate on this Ch'an buddhist koan that I just made up in my head: Is the water the wave? 73, Tom Donaly, KA6RUH Article: 223060 of rec.radio.amateur.antenna From: "Tom Donaly" Subject: Re: Current through coils References: <1144037197.028238.241940@u72g2000cwu.googlegroups.com> <3357-4430BC0D-178@storefull-3258.bay.webtv.net> <1144051302.246237.78830@e56g2000cwe.googlegroups.com> <44310045$0$2110$5a62ac22@per-qv1-newsreader-01.iinet.net.au> Message-ID: <4bdYf.11342$tN3.6347@newssvr27.news.prodigy.net> Date: Mon, 03 Apr 2006 17:45:36 GMT Cecil Moore wrote: > Mike Coombes wrote: > >> I don't understand what you are all on about, but, I side with K7ITM >> "K7ITM" wrote in message >> Regards Mike. > > > 1. If the magnitude of the forward current is the same at > both ends of the coil, there is no net storage of charge. > > 2. If the magnitude of the reflected current is the same at > both ends of the coil, there is no net storage of charge. > > These conditions satisfies K7ITM's requirements. But he > is being fooled by the sum of the two above currents > which is meaningless to net charge storage. > > Statements 1 and 2, above, already prove there is no net > storage of charge. Looking at the standing wave current > is meaningless after that technical fact. There is no "net" charge storage on a capacitor in an AC environment, either, Cecil, but you can still get current to go through it. I wouldn't argue with Tom too much if I were you, Cecil, because without the facts he's pointed out in regards to charge, your inchoate theorizing wouldn't mean anything at all. 73, Tom Donaly, KA6RUH Article: 223061 of rec.radio.amateur.antenna Subject: Re: Amother look at a choke balun. From: Dave Oldridge References: Message-ID: Date: Mon, 03 Apr 2006 17:51:24 GMT "Reg Edwards" wrote in news:gN2dnYqR4JwhwK3ZRVnygA@bt.com: > - - - - and placing a choke at 1/4-wave intervals all along the > transmission line is not of great help - it is effective only at one > frequency. Actually, it's pretty effective at all frequencies below that one. -- Dave Oldridge+ ICQ 1800667 VA7CZ Article: 223062 of rec.radio.amateur.antenna Subject: Re: The Seven Warning Signs of Bogus Science From: Dave Oldridge References: <442D5289.E6EFBD9A@shaw.ca> <4430a096@clear.net.nz> Message-ID: Date: Mon, 03 Apr 2006 18:13:51 GMT cliff wright wrote in news:4430a096 @clear.net.nz: > Irv Finkleman wrote: >> I thought this article might be of interest in that we often see >> claims about certain types of antennas which fall into the >> category. >> >> From >> http://chronicle.com/free/v49/i21/21b02001.htm >> >> POINT OF VIEW >> The Seven Warning Signs of Bogus Science >> By ROBERT L. PARK >> >> The National Aeronautics and Space Administration is investing close to >> a million dollars in an obscure Russian scientist's antigravity >> machine, although it has failed every test and would violate the most >> fundamental laws of nature. The Patent and Trademark Office recently >> issued Patent 6,362,718 for a physically impossible motionless >> electromagnetic generator, which is supposed to snatch free energy from >> a vacuum. And major power companies have sunk tens of millions of >> dollars into a scheme to produce energy by putting hydrogen atoms into >> a state below their ground state, a feat equivalent to mounting an >> expedition to explore the region south of the South Pole. >> >> There is, alas, no scientific claim so preposterous that a scientist >> cannot be found to vouch for it. And many such claims end up in a court >> of law after they have cost some gullible person or corporation a lot >> of money. How are juries to evaluate them? >> >> Before 1993, court cases that hinged on the validity of scientific >> claims were usually decided simply by which expert witness the jury >> found more credible. Expert testimony often consisted of tortured >> theoretical speculation with little or no supporting evidence. Jurors >> were bamboozled by technical gibberish they could not hope to follow, >> delivered by experts whose credentials they could not evaluate. >> >> In 1993, however, with the Supreme Court's landmark decision in Daubert >> v. Merrell Dow Pharmaceuticals, Inc. the situation began to change. The >> case involved Bendectin, the only morning-sickness medication ever >> approved by the Food and Drug Administration. It had been used by >> millions of women, and more than 30 published studies had found no >> evidence that it caused birth defects. Yet eight so-called experts were >> willing to testify, in exchange for a fee from the Daubert family, that >> Bendectin might indeed cause birth defects. >> >> In ruling that such testimony was not credible because of lack of >> supporting evidence, the court instructed federal judges to serve as >> "gatekeepers," screening juries from testimony based on scientific >> nonsense. Recognizing that judges are not scientists, the court invited >> judges to experiment with ways to fulfill their gatekeeper >> responsibility. >> >> Justice Stephen G. Breyer encouraged trial judges to appoint >> independent experts to help them. He noted that courts can turn to >> scientific organizations, like the National Academy of Sciences and the >> American Association for the Advancement of Science, to identify >> neutral experts who could preview questionable scientific testimony and >> advise a judge on whether a jury should be exposed to it. Judges are >> still concerned about meeting their responsibilities under the Daubert >> decision, and a group of them asked me how to recognize questionable >> scientific claims. What are the warning signs? >> >> I have identified seven indicators that a scientific claim lies well >> outside the bounds of rational scientific discourse. Of course, they >> are only warning signs -- even a claim with several of the signs could >> be legitimate. >> >> 1. The discoverer pitches the claim directly to the media. The >> integrity of science rests on the willingness of scientists to expose >> new ideas and findings to the scrutiny of other scientists. Thus, >> scientists expect their colleagues to reveal new findings to them >> initially. An attempt to bypass peer review by taking a new result >> directly to the media, and thence to the public, suggests that the work >> is unlikely to stand up to close examination by other scientists. >> >> One notorious example is the claim made in 1989 by two chemists from >> the University of Utah, B. Stanley Pons and Martin Fleischmann, that >> they had discovered cold fusion -- a way to produce nuclear fusion >> without expensive equipment. Scientists did not learn of the claim >> until they read reports of a news conference. Moreover, the >> announcement dealt largely with the economic potential of the discovery >> and was devoid of the sort of details that might have enabled other >> scientists to judge the strength of the claim or to repeat the >> experiment. (Ian Wilmut's announcement that he had successfully cloned >> a sheep was just as public as Pons and Fleischmann's claim, but in the >> case of cloning, abundant scientific details allowed scientists to >> judge the work's validity.) >> >> Some scientific claims avoid even the scrutiny of reporters by >> appearing in paid commercial advertisements. A health-food company >> marketed a dietary supplement called Vitamin O in full-page newspaper >> ads. Vitamin O turned out to be ordinary saltwater. >> >> 2. The discoverer says that a powerful establishment is trying to >> suppress his or her work. The idea is that the establishment will >> presumably stop at nothing to suppress discoveries that might shift the >> balance of wealth and power in society. Often, the discoverer describes >> mainstream science as part of a larger conspiracy that includes >> industry and government. Claims that the oil companies are frustrating >> the invention of an automobile that runs on water, for instance, are a >> sure sign that the idea of such a car is baloney. In the case of cold >> fusion, Pons and Fleischmann blamed their cold reception on physicists >> who were protecting their own research in hot fusion. >> >> 3. The scientific effect involved is always at the very limit of >> detection. Alas, there is never a clear photograph of a flying saucer, >> or the Loch Ness monster. All scientific measurements must contend with >> some level of background noise or statistical fluctuation. But if the >> signal-to-noise ratio cannot be improved, even in principle, the effect >> is probably not real and the work is not science. >> >> Thousands of published papers in para-psychology, for example, claim to >> report verified instances of telepathy, psychokinesis, or precognition. >> But those effects show up only in tortured analyses of statistics. The >> researchers can find no way to boost the signal, which suggests that it >> isn't really there. >> >> 4. Evidence for a discovery is anecdotal. If modern science has learned >> anything in the past century, it is to distrust anecdotal evidence. >> Because anecdotes have a very strong emotional impact, they serve to >> keep superstitious beliefs alive in an age of science. The most >> important discovery of modern medicine is not vaccines or antibiotics, >> it is the randomized double-blind test, by means of which we know what >> works and what doesn't. Contrary to the saying, "data" is not the >> plural of "anecdote." >> >> 5. The discoverer says a belief is credible because it has endured for >> centuries. There is a persistent myth that hundreds or even thousands >> of years ago, long before anyone knew that blood circulates throughout >> the body, or that germs cause disease, our ancestors possessed >> miraculous remedies that modern science cannot understand. Much of what >> is termed "alternative medicine" is part of that myth. >> >> Ancient folk wisdom, rediscovered or repackaged, is unlikely to match >> the output of modern scientific laboratories. >> >> 6. The discoverer has worked in isolation. The image of a lone genius >> who struggles in secrecy in an attic laboratory and ends up making a >> revolutionary breakthrough is a staple of Hollywood's science-fiction >> films, but it is hard to find examples in real life. Scientific >> breakthroughs nowadays are almost always syntheses of the work of many >> scientists. >> >> 7. The discoverer must propose new laws of nature to explain an >> observation. A new law of nature, invoked to explain some extraordinary >> result, must not conflict with what is already known. If we must change >> existing laws of nature or propose new laws to account for an >> observation, it is almost certainly wrong. >> >> I began this list of warning signs to help federal judges detect >> scientific nonsense. But as I finished the list, I realized that in our >> increasingly technological society, spotting voodoo science is a skill >> that every citizen should develop. >> >> Robert L. Park is a professor of physics at the University of Maryland >> at College Park and the director of public information for the American >> Physical Society. He is the author of Voodoo Science: The Road From >> Foolishness to Fraud (Oxford University Press, 2002). >> >> http://chronicle.com >> Section: The Chronicle Review >> Volume 49, Issue 21, Page B20 > > Some good points there Irv! > 7. Is very interesting though. I'm an amateur astronomer as well as a ham > and I'm frequently amused, or saddened, by some of the extreme efforts > to "save" the "Big Bang" theory. > One recent one had negative mass matter, a cosmic repulsion force which > has never been observed and cold dark invisible matter all brought in. > Of course there are WIMPS MACHOS and a period of inflation at many times > the speed of light involved too. > To me that makes the "Big Bang" a very suspect theory!! It IS very suspect. The trouble is, nobody has an iota of a clue what to replace it with. And this will probably remain the case until we have some solid quantum theory of gravity to work with. > And that IS the position of many of the "establishment" cosmologists! > These problems are not just on the science "fringe" unfortunately. > A couple of brave souls recently proposed the simple expedient of very > slighty modifing the inverse square law of gravity at vast distances. > It seems to explain many problems of current theories, but it was > "jumped on" from a great height by scientists who don't ever seem to > have heard of Occam's razor. Yes...very often the replacement "laws of nature" turn out to approximate very closely to the ones we had before. After all, a "law of nature" is really just a VERY persistent (and often mathematical) observation about nature. > Regards Cliff wright. > > BTW I have a bet with several of my old colleagues at Auckland > university that LIGO won't detect any "gravitational waves" > So far it has been about 3 years and I haven't had to pay out. But we ARE dealing with a phenomenon that is at the limit of detection here. -- Dave Oldridge+ ICQ 1800667 Article: 223063 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Current through coils References: <1144037197.028238.241940@u72g2000cwu.googlegroups.com> <3357-4430BC0D-178@storefull-3258.bay.webtv.net> <1144051302.246237.78830@e56g2000cwe.googlegroups.com> <1144081585.216717.291770@i39g2000cwa.googlegroups.com> Message-ID: <_0eYf.11353$tN3.5319@newssvr27.news.prodigy.net> Date: Mon, 03 Apr 2006 18:43:06 GMT K7ITM wrote: > "Cyclical variation in charge (contained > within a volume)" means that on average the charge stays constant, but > it does not mean that it's constant over some arbitratily short but > finite length of time. The current reported by EZNEC is RMS current, Tom. What happens within a cycle is irrelevant to this discussion. We are not and never have been discussing variations within a cycle. There's just no point. We have been discussing RMS values of currents. Your attempt to again divert the issue is noted. We are talking about net charge spread out over many steady-state cycles. That net charge is always zero no matter what the RMS value of the standing wave current at the ends of the coil. > Without the capacitance, without the ability to store charge, a > transmission line, an antenna wire, a loading coil, all of them--would > not have the ability to cause delay. Freespace, without a non-zero > permittivity (capacitance), would allow infinite speed of light. But > all these things DO have capacitance, and they DO have > speed-of-propagation at the speed of light or slower. Please tell us something we don't already know. It has become apparent that the discussion is not about coils at all. It is about the nature of standing waves whether existing in a transmission line, a standing wave antenna wire, or a coil. -- 73, Cecil http://www.qsl.net/w5dxp Article: 223064 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Coils and Transmission Lines. References: <3gSXf.63583$Jd.40227@newssvr25.news.prodigy.net> Message-ID: Date: Mon, 03 Apr 2006 18:58:36 GMT Tom Donaly wrote: > If it's a solution to the wave equation it's o.k., Cecil, but > Hecht is still not using the case where there is a phase difference > between the two waves. Yes, he is, Tom. The phase *disappears* when you add the two traveling waves. That you don't recognize that fact of physics is the source of your misconception. The forward and reflected wave phasors are rotating in opposite directions at the same angular velocity. That makes their sum a constant phase value for half the cycle and the opposite constant phase value for the other half of the cycle. I and Richard Harrison have already explained that a number of times quoting Kraus and Terman. Here are a number of problems. I(f) is forward current and I(r) is reflected current. Please everybody, perform the following phasor additions where I(f)+I(r) is the *standing wave current*: I(f) I(r) I(f)+I(r) 1 amp at 0 deg 1 amp at 0 deg _________________ 1 amp at -30 deg 1 amp at +30 deg _________________ 1 amp at -60 deg 1 amp at +60 deg _________________ 1 amp at -90 deg 1 amp at +90 deg _________________ 1 amp at -120 deg 1 amp at +120 deg _________________ 1 amp at -150 deg 1 amp at +150 deg _________________ 1 amp at -180 deg 1 amp at +180 deg _________________ If you guys will take pen to paper and fill in those blanks you will uncover the misconception that has haunted this newsgroup for many weeks. If you need help with the math, feel free to ask for help. -- 73, Cecil http://www.qsl.net/w5dxp Article: 223065 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Coils and Transmission Lines. References: <1lcYf.65823$dW3.37762@newssvr21.news.prodigy.com> Message-ID: Date: Mon, 03 Apr 2006 19:01:27 GMT Tom Donaly wrote: > When are you going to consider > field theory in your analysis, Cecil? That's a fair question, Tom. The answer is just as soon as someone comes up with an example for which the distributed network model fails. We have plenty of examples where the lumped circuit model fails but not one example yet that the distributed network model won't handle. -- 73, Cecil http://www.qsl.net/w5dxp Article: 223066 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Current across the antenna loading coil - from scratch References: <1143142526.021154.67050@e56g2000cwe.googlegroups.com> <1144062834.591149.121920@v46g2000cwv.googlegroups.com> <69aYf.63812$Jd.56966@newssvr25.news.prodigy.net> Message-ID: Date: Mon, 03 Apr 2006 19:07:01 GMT Tom Donaly wrote: > Hecht was talking about two opposing waves of the same phase and > amplitude interfering with each other. You can't guarantee, in a real > antenna, that the two waves do have the same phase and magnitude. :-) Hecht was talking about two coherent EM waves traveling in opposite directions. We are talking about two coherent EM waves traveling in opposite directions. There is a small traveling wave component but it doesn't affect the standing wave. It is what is left over from the standing wave. This discussion has not been about coils. We need to discuss an unterminated lossless transmission line and then move on to 1/2 wavelength thin-wire standing wave antennas. -- 73, Cecil http://www.qsl.net/w5dxp Article: 223067 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Current across the antenna loading coil - from scratch References: <1143142526.021154.67050@e56g2000cwe.googlegroups.com> <1144062834.591149.121920@v46g2000cwv.googlegroups.com> <69aYf.63812$Jd.56966@newssvr25.news.prodigy.net> <1fWdnQLbJqyMyqzZnZ2dnUVZ_smdnZ2d@adelphia.com> Message-ID: <0veYf.11366$tN3.1035@newssvr27.news.prodigy.net> Date: Mon, 03 Apr 2006 19:15:08 GMT John Popelish wrote: > Cecil Moore wrote: >> That is a false statement and is at the root of the misconceptions. >> Standing wave current does not have to be equal. > > I assume you are meaning that the RMS current at one physical point must > not equal the RMS current at some other point. Yes, the RMS value of the standing wave current at the bottom of the coil doesn't have to bear any relationship to the RMS value of the standing wave current at the top of the coil. > Aren't you claiming that the coil has transmission line like properties, > in that it takes time for a wave to pass through it? Yes > Any such device needs two mechanisms for storing energy, one magnetic > (inductive) and one electrical (capacitive). Even free space has both. > If you eliminate either mechanism (or make one of them insignificant, as > would happen to the capacitance if the inductor approaches zero size), > you lose the transmission line like properties as the dominant mechanism. There is no net charge carried over from cycle to cycle. There is no net storage of charge even if the steady-state RMS value of the standing wave current is zero at one end of the coil and 2 amps at the other end. The problem here is not how a coil works. The problem is how standing waves work. Forget the coil. Start with a lossless unterminated transmission line and then step up to a 1/2 wavelength thin wire dipole. It is obvious that a number of people just don't understand the nature of a standing wave that doesn't move through a wire along with its phasor that doesn't rotate relative to the source. -- 73, Cecil http://www.qsl.net/w5dxp Article: 223068 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Current through coils References: <2sM63YaI$EMEFAeb@ifwtech.co.uk> <11762-44307642-861@storefull-3252.bay.webtv.net> Message-ID: Date: Mon, 03 Apr 2006 19:18:00 GMT Tom Donaly wrote: > Cecil, since you always leave the phase information out of > your version of the solution of the wave equation, I don't > think Diogenes is going to be knocking on your door anytime soon, > either. I'm not leaving phase out, Tom, Mother Nature leaves phase out of the standing wave equation. What is it about Gene Fuller's posting that you don't understand? Regarding the cos(kz)*cos(wt) term in a standing wave: > Gene Fuller, W4SZ wrote: >> In a standing wave antenna problem, such as the one you describe, there is no >> remaining phase information. Any specific phase characteristics of the traveling >> waves died out when the startup transients died out. >> >> Phase is gone. Kaput. Vanished. Cannot be recovered. Never to be seen again. >> >> The only "phase" remaining is the cos (kz) term, which is really an amplitude >> description, not a phase. -- 73, Cecil http://www.qsl.net/w5dxp Article: 223069 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Current through coils References: <1144051302.246237.78830@e56g2000cwe.googlegroups.com> <11783-44312BB4-911@storefull-3254.bay.webtv.net> <1144086329.511819.304050@v46g2000cwv.googlegroups.com> Message-ID: <7zeYf.11368$tN3.10940@newssvr27.news.prodigy.net> Date: Mon, 03 Apr 2006 19:19:31 GMT w8ji@akorn.net wrote: > Wow! First he uses TWT's. > ....and then he shifts it to traps!!! > Next heating elemennts or slinkys I suppose. Wow, consider the technical content of your posting and wonder why there is none. -- 73, Cecil http://www.qsl.net/w5dxp Article: 223070 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Current through coils References: <1144037197.028238.241940@u72g2000cwu.googlegroups.com> <3357-4430BC0D-178@storefull-3258.bay.webtv.net> <1144051302.246237.78830@e56g2000cwe.googlegroups.com> <44310045$0$2110$5a62ac22@per-qv1-newsreader-01.iinet.net.au> <4bdYf.11342$tN3.6347@newssvr27.news.prodigy.net> Message-ID: Date: Mon, 03 Apr 2006 19:22:00 GMT Tom Donaly wrote: > There is no "net" charge storage on a capacitor in an AC > environment, either, Cecil, but you can still get current > to go through it. True, but completely irrelevant to the present discussion so more than likely another straw man. Once more, the subject is the RMS standing wave envelope reported by EZNEC. Brownian motion of individual electrons is completely irrelevant. -- 73, Cecil http://www.qsl.net/w5dxp Article: 223071 of rec.radio.amateur.antenna From: Michael Coslo Subject: Re: What is an EH antenna Date: Mon, 03 Apr 2006 15:59:39 -0400 Message-ID: References: <1143908604.326393.313760@j33g2000cwa.googlegroups.com> <2yUXf.18997$B_1.11490@edtnps89> <1230fue8b8chkbf@corp.supernews.com> <1144027979.662007.152180@g10g2000cwb.googlegroups.com> Cecil Moore wrote: > w8ji@akorn.net wrote: >> No matter what facts multiple independent sources submit, those who >> have faith will ignore the facts. > > :-) That apparently includes individuals with faith in the > lumped circuit model under conditions where it is known to > fail. :-) Aww Cecil, does every thread have to turn into that? 8^) -73 de Mike KB3EIA - Article: 223072 of rec.radio.amateur.antenna From: richardharrison@webtv.net (Richard Harrison) Subject: Re: Current through coils Date: Mon, 3 Apr 2006 14:44:28 -0600 Message-ID: <27505-4431892C-1147@storefull-3257.bay.webtv.net> References: <1144089425.456333.273820@i39g2000cwa.googlegroups.com> Tom, K7ITM wrote: "A voltage applied to the feedpoint terminals of an antenna causes CHARGE to be put in motion. Accumulation of CHARGE along the conductors--the distribution of charge as a function of time and space--in turn results in electric fields in the vicinity of the antenna." Agreed that current is charge in motion. Accumulation of charge, however, is a job for an accumulator, another name for a storage battery. These have little to do with the possibility of an antenna coil having currents through the coil from opposite directions creating unequal totals at the ends of the coil. I don`t know if this Tom is picking a fight to gain attention before going to Dayton but his postings have the right fragarance. Best regards, Richard Harrison, KB5WZI Article: 223073 of rec.radio.amateur.antenna From: "Steve Nosko" Subject: Re: RF/microwaves over Fiberoptic cable??? Date: Mon, 3 Apr 2006 16:15:30 -0500 Message-ID: References: <3cc6g3-meh.ln1@p400bob.personal.cox.net> These cellular extenders (that I am familiar with) were a simple way to put a broadband "antenna" at a remote location and have it behave as if it was connected by coax. One sector antenna of a cell site could be allocated to the remote location and all the control and system interface wasn't complicated in any way -- except for accounting for the coverage area (which was usually a RF hole needing coverage). With the amount of equipment required to do it right (modulate the RF onto the fiber and demodulate it and amplify it back to the required level), it would be just as easy for a ham to simply put the rig at the remote location and send control and audio up the fiber -- if he really wanted the advantages of fiber. There are fiber boxes that do this for a fraction of the cost of the "RF" type --- they have audio and digital interfaces. If you can do it on the Internet, fiber is simple as well. 73, Steve, K9DCI "Bob Bob" wrote in message news:3cc6g3-meh.ln1@p400bob.personal.cox.net... > Hi Marco > > Yes but its more of use in a commercial/military than amateur radio > environment. > > I remember that certain cellular site installs I was involved in ran > fiber from a the "main" RF TX/RX device to a remote location. The remote > location simply had a broadband amplifier for the separate TX and RX. > This was used in an underground railway station going out to maybe 3-4 > locations. It was more cost effective doing it this way than by long > coax runs at 900/1800MHz. > > It will be a cost/benefit tradeoff of whatever RF/SMOF/RF interface > device you have to purchase vs the cost of coax vs fiber. > > This is something an amateur radio person isnt likely to do for his/her > hobby. I also doubt whether it will be commercially viable for amateur > radio manufacturers to include fiber interfacing. > > OBTW you can tap/intercept optical fibre . > > Cheers Bob W5/VK2YQA > > Marco Licetti wrote: > > I am not here to pester about own company - I do NOT work for this but just > > to share experience: Article: 223074 of rec.radio.amateur.antenna From: richardharrison@webtv.net (Richard Harrison) Subject: Re: Current across the antenna loading coil - from scratch Date: Mon, 3 Apr 2006 16:24:55 -0600 Message-ID: <11783-4431A0B7-956@storefull-3254.bay.webtv.net> References: <0hf13258667d7d0m648bf6rbgm6ecrj2sl@4ax.com> Richard Clark wrote: "This must be a convention that is particular to only a very few hams. The FCC database describes AM antennas in both electrical degrees and physical height as follows." It is the convention to describe AM broadcast towers in electrical degrees. Harold Ennes reprints an RCA resistance chart for heights between 50 and 200 degrees in "AM-FM Broadcast Maintenance". Formula given is: Height in electrical degrees = Height in feet X frequency in kc X 1.016 X 10 to the minus 6 power. Example Towers: 50-degrees self-supporting: R=7. jx=-j100 50-degrees guyed mast: R=8, jx=-j222 90-degrees self-supporting: R=40, jx=+j35 90-degrees guyed mast: R=36, jx=j0 200-degrees self-supporting: R=23, jx=-j50 200-degrees guyed mast: R=80, jx=-400 There are values of R and X for 16 different heights. If you are interested, look at the book. Best regards, Richard Harrison, KB5WZI Article: 223075 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Coils and Transmission Lines. References: <3gSXf.63583$Jd.40227@newssvr25.news.prodigy.net> <5K2dnefSBq80B6zZRVn-ug@adelphia.com> Message-ID: Date: Mon, 03 Apr 2006 22:53:17 GMT John Popelish wrote: > What misconception? That all current in a standing wave has the same > phase, rather than one of two possible phases? The misconception is not yours, John. W7EL used that current to try to measure the phase shift through a coil and so did W8JI who came up with an unbelievable 3 nS. -- 73, Cecil http://www.qsl.net/w5dxp Article: 223076 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Current across the antenna loading coil - from scratch References: <1143142526.021154.67050@e56g2000cwe.googlegroups.com> <1144062834.591149.121920@v46g2000cwv.googlegroups.com> <69aYf.63812$Jd.56966@newssvr25.news.prodigy.net> <1fWdnQLbJqyMyqzZnZ2dnUVZ_smdnZ2d@adelphia.com> <0veYf.11366$tN3.1035@newssvr27.news.prodigy.net> <8redneWq1um7A6zZRVn-iw@adelphia.com> Message-ID: Date: Mon, 03 Apr 2006 23:05:51 GMT John Popelish wrote: > Of course. no one is talking about the red herring of charge stored > over a whole cycle. Of course, *everyone* except you and Tom Donaly are talking about charge stored over a whole cycle. That's the entire base of their arguments. The unbalance in the *RMS* current at the bottom of the coil and the *RMS* current at the top of the coil is what the entire discussion is all about. The currents measured by W8JI and W7EL were *RMS* currents. The currents reported by EZNEC are *RMS* currents. > And no one but you brings up "net storage". We are all talking about > ordinary capacitive charge storage within a cycle. If so, that is completely irrelevant to the discussion since W8JI and W7EL are using *RMS* currents for their measurements and EZNEC is reporting *RMS* currents. Let me summarize it for you. W8JI and W7EL apparently think that the RMS current value of zero at the bottom of the coil Vs the RMS current value of one amp at the top of the coil means energy is being sucked into the coil from some external source. How about assisting in a tutorial on standing waves rather than diverting and obfuscating the issues? -- 73, Cecil http://www.qsl.net/w5dxp Article: 223077 of rec.radio.amateur.antenna From: Roy Lewallen Subject: Re: Current across the antenna loading coil - from scratch Date: Mon, 03 Apr 2006 16:25:55 -0700 Message-ID: <1233bo6bgqfh561@corp.supernews.com> References: <1143142526.021154.67050@e56g2000cwe.googlegroups.com> <1144062834.591149.121920@v46g2000cwv.googlegroups.com> <69aYf.63812$Jd.56966@newssvr25.news.prodigy.net> <1fWdnQLbJqyMyqzZnZ2dnUVZ_smdnZ2d@adelphia.com> <0veYf.11366$tN3.1035@newssvr27.news.prodigy.net> <8redneWq1um7A6zZRVn-iw@adelphia.com> John Popelish wrote: > . . . > It is obvious to me that you are one of them. Every point on a line > carrying a standing wave (except the node points) has AC voltage on it, > and AC current through it. The amplitude and phase of those voltages > and currents can be described as a phasor, with respect to some > reference phase of the same frequency. As you move along the line, the > amplitude changes and when you pass through a node the phase reverses. > So the phasor does not rotate with position change, except for a step > change of 180 degrees at nodes, rather than smooth rotation with respect > to position. > > For a traveling wave, every point on the line has an AC voltage on it, > and an AC current passing through it. The amplitude is constant along > the line, but the phasor rotates as you move along the line (the phase > is linearly dependent on position). But at any single point on the > line, a non rotating phasor describes the amplitude and phase with > respect to a reference phase of the same frequency. There's a potential for ambiguity here, and that ambiguity has been used a number of times in this thread to cause confusion. So let me try to clarify things. All phasors "rotate", in that every one contains an implicit term e^jwt. That term describes a rotation of the complex phasor quantity at the rotational frequency w (omega), but no change in amplitude. If a quantity doesn't include this implicit term, it's not a phasor, by definition. We can look at any phasor quantity in a system and compare the phase of its rotation with the phase of a reference, and from this assign a phase angle to it. In steady state, the phase angle doesn't change with time -- it's the phase difference between the w - rotating phasor and the w - rotating reference. Phasors of different rotational rates (that is, of different frequencies) can't be combined in the same analysis, unless the implicit term is made explicit, in which case they're no longer phasors. The use of "rotation" in John's posting is talking about a change of phase with physical position. This usage has been confused with the time rotation of the phasor which comes from the implicit e^jwt term. I'd prefer to use the term "phase", which doesn't change with time in a steady state system, directly rather than "rotation" to describe a change in phase with position. With that convention, we see that the phase of a pure traveling wave changes linearly with position. But when we sum forward and reverse traveling waves together to get a total current (or voltage), the phase of the total current (or voltage) is no longer a linear function of position. In the special case of an open or short circuited transmission line, where the forward and reverse traveling waves are equal in amplitude, the phase doesn't change with position at all (except for a periodic reversal in current and voltage direction, which can be interpreted as a 180 degree phase change). But the phasor representing total voltage or current (which Cecil refers to as "standing wave current") at any point, which is the sum of two phasors representing forward and reverse traveling waves, does indeed rotate at w (omega) radians/second rate, just like its constituent phasors. The constant phase with position (of an open or shorted line) simply means that if you froze time at some instant and looked at the angles of the rotating phasors representing the total current at each point along the line, you'd find them all to be at the same angle. They're all rotating. This isn't revolutionary or controversial -- you can find phasors discussed in any elementary circuit analysis text.[*] And it's not difficult to do the summation of forward and reverse traveling waves to see the result, but if you'd like to see how someone else did it, one of the clearest discussions I've found is in Chipman's _Transmission Lines_, a Schaum's Outline book. [*] You have to be a little careful, though. In most introductions to phasors, the author introduces the e^jwt term early on, and quickly drops it from the phasor notation as is customary. So it's easy to forget it's there. But remembering that it is there is vital to understanding this topic, and to keep from being misled by misdirection which takes advantage of confusion and abbreviated notation. Roy Lewallen, W7EL Article: 223078 of rec.radio.amateur.antenna From: ml Subject: Re: paint antenna? References: <122u6ah1aa5iv2e@corp.supernews.com> Message-ID: Date: Tue, 04 Apr 2006 00:24:41 GMT In article <122u6ah1aa5iv2e@corp.supernews.com>, "David G. Nagel" wrote: > ml wrote: > > > just read a article someplace about a new conductive paint that is going > > to be used by different sources (pvt/mil) to in effect paint an antenna > > on a surface. once such use was an 'orbiting' blimp , planes etc to > > repete signals > > > > > > ok so i wonder my roof has a flat brick wall it's 40ft tall 40ft wide > > > > if i painted a antenna design think i'd get any useful performance in at > > least one direction? > > > > unf it didn't state any spec's but it's commercial > > > > > > just really thinking out louad how a antenna w/little profile but > > otherwise large surfacce area might work > > Actually if the paint is continuous in it's conductivity there is no > reason why a painted antenna picture would not work. Tuning it might be > problematic but would work. > Try it and report back. > > Dave WD9BDZ the bricks have been recently waterproffed, thou i guess they will still be soggy after a strong rain guess i'd just have to add a small amount of paint, and keep painting till swr etc are where it need to be to make resonant if it even works sounds like a fun experiment can't wait to snag some paint Article: 223079 of rec.radio.amateur.antenna From: Roy Lewallen Subject: Re: Current across the antenna loading coil - from scratch Date: Mon, 03 Apr 2006 18:39:12 -0700 Message-ID: <1233ji3112ktg52@corp.supernews.com> References: <1143142526.021154.67050@e56g2000cwe.googlegroups.com> <1144062834.591149.121920@v46g2000cwv.googlegroups.com> <69aYf.63812$Jd.56966@newssvr25.news.prodigy.net> <1fWdnQLbJqyMyqzZnZ2dnUVZ_smdnZ2d@adelphia.com> <0veYf.11366$tN3.1035@newssvr27.news.prodigy.net> <8redneWq1um7A6zZRVn-iw@adelphia.com> <1144111853.486784.119070@i39g2000cwa.googlegroups.com> w8ji@akorn.net wrote: >> Cecil Moore wrote: >>> Let me summarize it for you. W8JI and W7EL apparently think >>> that the RMS current value of zero at the bottom of the coil >>> Vs the RMS current value of one amp at the top of the coil >>> means energy is being sucked into the coil from some external >>> source. > >> John Popelish wrote: >> I don't read their responses that way. I read their responses as >> saying that the current leaving or entering an end of an inductor >> includes a capacitive component and an inductive component. The >> capacitive current branches out of the coil to the surrounding space, >> and is what allows a measured difference in the currents passing >> through its two ends. The path through the wire to the other end is >> not the only path for current. > > You read what I wrote and what Roy wrote correctly John. > > Cecil changes what other people write to suit his own needs. He changes > what other people say, and then points out why the creatively edited > text he invented is wrong. That's his debating style. Watch out for it! Absolutely true. Cecil complains that people won't engage in a technical discussion with him. Many have tried, and all we get in response is evasion, misquotes, diversion, and brushing off of any evidence contrary to his preconceived notions. Anyone who wants to know what I said or what I think should read what I've posted. If it's not clear, ask. But don't trust Cecil to tell you. Roy Lewallen, W7EL Article: 223080 of rec.radio.amateur.antenna From: aRKay Subject: HDTV Antennas Message-ID: Date: Tue, 04 Apr 2006 01:43:04 GMT What is unique about the new HDTV antennas? We just picked up a new HDTV with a tuner and was advised to pickup a simple HDTV antenna to pick up the local digital broadcast. Any magic to these other the high gain claims on the boxes? Dick AA5VU Article: 223081 of rec.radio.amateur.antenna From: "David G. Nagel" Subject: Re: HDTV Antennas Date: Mon, 03 Apr 2006 20:48:46 -0500 Message-ID: <1233k55622e9u4c@corp.supernews.com> References: aRKay wrote: > What is unique about the new HDTV antennas? We just picked up a new > HDTV with a tuner and was advised to pickup a simple HDTV antenna to > pick up the local digital broadcast. Any magic to these other the high > gain claims on the boxes? > > Dick AA5VU Dick; There is absolutely nothing unique about a so called HDTV antenna. I would get a good quality antenna though. Stations are currently transmitting at reduced power to save a few dollars until they have to goto high power. Dave WD9BDZ Article: 223082 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Coils and Transmission Lines. References: <3gSXf.63583$Jd.40227@newssvr25.news.prodigy.net> Message-ID: Date: Tue, 04 Apr 2006 02:06:39 GMT Tom Donaly wrote: > If it disappears, you've done something wrong. There is no phase information in standing wave phase, Tom. I can't find it, Gene fuller can't find it, Eugene Hecht can't find it, and James Clerk Maxwell can't find it. Any and all phase information in the standing wave phase disappears during superposing. Let me give you another example. Assume that we superpose one amp of DC current flowing in one direction and one amp of DC current flowing in the other direction. What does the superposed amplitude tell us about the amplitudes of the superposed currents? Nothing, except they were equal. -- 73, Cecil http://www.qsl.net/w5dxp Article: 223083 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Current across the antenna loading coil - from scratch References: <1143142526.021154.67050@e56g2000cwe.googlegroups.com> <1144062834.591149.121920@v46g2000cwv.googlegroups.com> <69aYf.63812$Jd.56966@newssvr25.news.prodigy.net> Message-ID: Date: Tue, 04 Apr 2006 02:13:05 GMT Tom Donaly wrote: > Has it ever occurred to you, Cecil, that a half wave dipole with > equal current and voltage waves traveling in opposite directions > wouldn't accept power? It is an approximation, Tom, like a lossless line. For real world dipoles, the voltage and current decay by about 10% between the forward wave and the arrival of the reflected wave. Kraus and Terman both use that approximation in their examples. We aren't saying anything about the traveling wave part of the waves. The discussion is about the standing wave portion of the wave which, by definition, requires equal magnitudes. -- 73, Cecil http://www.qsl.net/w5dxp Article: 223084 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Current across the antenna loading coil - from scratch References: <1143142526.021154.67050@e56g2000cwe.googlegroups.com> <1144062834.591149.121920@v46g2000cwv.googlegroups.com> <69aYf.63812$Jd.56966@newssvr25.news.prodigy.net> <1fWdnQLbJqyMyqzZnZ2dnUVZ_smdnZ2d@adelphia.com> <0veYf.11366$tN3.1035@newssvr27.news.prodigy.net> <8redneWq1um7A6zZRVn-iw@adelphia.com> <1233bo6bgqfh561@corp.supernews.com> Message-ID: Date: Tue, 04 Apr 2006 02:22:08 GMT Roy Lewallen wrote: > The constant > phase with position (of an open or shorted line) simply means that if > you froze time at some instant and looked at the angles of the rotating > phasors representing the total current at each point along the line, > you'd find them all to be at the same angle. They're all rotating. Yes, when I said standing wave current phase doesn't rotate, I meant with respect to the source current phase. At any instant in time, the phase of the standing wave current is unchanging up and down the line. Assume the standing wave current all up and down the dipole is of constant phase with no variation with 'x'. Roy, you used that current to try to measure the delay through a coil. How did you plan to measure that delay with a signal known to be the same phase not only at both ends of the coil but all up and down the antenna? -- 73, Cecil http://www.qsl.net/w5dxp Article: 223085 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Current through coils References: <2sM63YaI$EMEFAeb@ifwtech.co.uk> <11762-44307642-861@storefull-3252.bay.webtv.net> Message-ID: Date: Tue, 04 Apr 2006 02:24:33 GMT Tom Donaly wrote: > Well, I guess it's o.k. for you to believe that when a wave travels down > a transmission line it always ends up in phase with where it started. > That simplifies things for your theory. It doesn't make for a very > good transmission line, though. It makes for a very good open-circuit stub. That's essentially what a standing wave antenna is - a lossy open-circuit stub. Thank goodness, the losses are to radiation. -- 73, Cecil http://www.qsl.net/w5dxp Article: 223086 of rec.radio.amateur.antenna Date: Mon, 03 Apr 2006 21:25:14 -0500 From: Tom Ring Subject: Re: What is an EH antenna References: <1143908604.326393.313760@j33g2000cwa.googlegroups.com> <2yUXf.18997$B_1.11490@edtnps89> <1230fue8b8chkbf@corp.supernews.com> <1144027979.662007.152180@g10g2000cwb.googlegroups.com> Message-ID: <4431d90a$0$7330$39cecf19@news.twtelecom.net> Cecil Moore wrote: > w8ji@akorn.net wrote: > >> No matter what facts multiple independent sources submit, those who >> have faith will ignore the facts. > > > :-) That apparently includes individuals with faith in the > lumped circuit model under conditions where it is known to > fail. :-) Cecil Please drop it. Not every subject is an attack on you, and the rest should not be used as an opportunity for your propoganda. It is very tiring. tom K0TAR Article: 223087 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Current across the antenna loading coil - from scratch References: <1143142526.021154.67050@e56g2000cwe.googlegroups.com> <1144062834.591149.121920@v46g2000cwv.googlegroups.com> <69aYf.63812$Jd.56966@newssvr25.news.prodigy.net> <1fWdnQLbJqyMyqzZnZ2dnUVZ_smdnZ2d@adelphia.com> <0veYf.11366$tN3.1035@newssvr27.news.prodigy.net> <8redneWq1um7A6zZRVn-iw@adelphia.com> Message-ID: Date: Tue, 04 Apr 2006 02:37:18 GMT John Popelish wrote: > Cecil Moore wrote: >> Of course, *everyone* except you and Tom Donaly are talking about >> charge stored over a whole cycle. > > Bull. If that's what you think and you can find someone to discuss energy exchange within a cycle, be my guest. As far as I know, Tom Donaly introduced the subject as a diversion. > I don't read their responses that way. I couldn't believe it either but after years of arguing with them, it is apparent that many of the gurus here on r.r.a.a are simply ignorant of the nature of standing waves. I really expected them to shout, "April Fool, we have been pulling your leg!" But, sad to say, they are serious about standing wave current "flowing" into the bottom of the coil and out the top. They apparently haven't read "Optics", by Hecht where he says: "E(x,t) = 2Eo*sin(kx)*cos(wt) This is the equation for a standing wave, as opposed to a traveling wave. Its profile does not move through space. ... [The standing wave] phasor doesn't rotate at all, and the resultant wave it represents doesn't progress through space - its a standing wave." If standing waves of light don't move through space, standing waves of RF don't move through a wire. >I read their responses as saying > that the current leaving or entering an end of an inductor includes a > capacitive component and an inductive component. The capacitive current > branches out of the coil to the surrounding space, and is what allows a > measured difference in the currents passing through its two ends. That is a secondary effect. The primary effect is the phasor addition of the forward current and reflected current which you provided. Compared to zero amps of standing wave current when the forward current phasor and the reflected current phasor are 180 degrees out of phase, just how much effect can capacitance have? -- 73, Cecil http://www.qsl.net/w5dxp Article: 223088 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Current across the antenna loading coil - from scratch References: <1143142526.021154.67050@e56g2000cwe.googlegroups.com> <1144062834.591149.121920@v46g2000cwv.googlegroups.com> <69aYf.63812$Jd.56966@newssvr25.news.prodigy.net> <1fWdnQLbJqyMyqzZnZ2dnUVZ_smdnZ2d@adelphia.com> <0veYf.11366$tN3.1035@newssvr27.news.prodigy.net> <8redneWq1um7A6zZRVn-iw@adelphia.com> <1144111853.486784.119070@i39g2000cwa.googlegroups.com> Message-ID: Date: Tue, 04 Apr 2006 02:46:48 GMT w8ji@akorn.net wrote: > Cecil changes what other people write to suit his own needs. He changes > what other people say, and then points out why the creatively edited > text he invented is wrong. That's his debating style. Watch out for it! Tom, do you or do you not believe that standing wave current flows into the bottom of the coil and out the top? It's a simple yes/no question. You have earlier stated that "current is current" and that, in spite of the different equations for for the two currents, standing wave current moves like traveling wave current in spite of what Hecht had to say in "Optics". "E(x,t) = 2*Eo*sin(kx)*cos(wt) This is the equation for a STANDING or STATIONARY WAVE, as opposed to a traveling wave. Its profile does not move through space; it is clearly not of the form Func(x +/- vt). ... [Standing wave phase] doesn't rotate at all, and the resultant wave it represents doesn't progress through space - its a standing wave." If standing waves of light don't move through space, standing waves of RF don't move through wires. Time to stop the ad hominem attacks and address this technical issue. -- 73, Cecil http://www.qsl.net/w5dxp Article: 223089 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Current across the antenna loading coil - from scratch References: <1143142526.021154.67050@e56g2000cwe.googlegroups.com> <1144062834.591149.121920@v46g2000cwv.googlegroups.com> <69aYf.63812$Jd.56966@newssvr25.news.prodigy.net> <1fWdnQLbJqyMyqzZnZ2dnUVZ_smdnZ2d@adelphia.com> <0veYf.11366$tN3.1035@newssvr27.news.prodigy.net> <8redneWq1um7A6zZRVn-iw@adelphia.com> <1144111853.486784.119070@i39g2000cwa.googlegroups.com> <1233ji3112ktg52@corp.supernews.com> Message-ID: Date: Tue, 04 Apr 2006 02:52:00 GMT Roy Lewallen wrote: > Absolutely true. Cecil complains that people won't engage in a technical > discussion with him. Many have tried, and all we get in response is > evasion, misquotes, diversion, and brushing off of any evidence contrary > to his preconceived notions. Roy, I'll tell you the same thing I told W8JI. It's time to stop the ad hominem attacks and discuss the technical issues. You tried to use standing wave current, containing no phase, to measure the delay through a coil. You have said previously that standing wave current flows just like traveling wave current. You said that in spite of what Hecht says in "Optics". Hecht had to say in "Optics": "E(x,t) = 2*Eo*sin(kx)*cos(wt) This is the equation for a STANDING or STATIONARY WAVE, as opposed to a traveling wave. Its profile does not move through space; it is clearly not of the form Func(x +/- vt). ... [Standing wave phase] doesn't rotate at all, and the resultant wave it represents doesn't progress through space - its a standing wave." If standing wave light doesn't move through space, then standing wave RF doesn't move through a wire. Do you disagree with Hecht? -- 73, Cecil http://www.qsl.net/w5dxp Article: 223090 of rec.radio.amateur.antenna From: "Tom Donaly" Subject: Re: Coils and Transmission Lines. References: <3gSXf.63583$Jd.40227@newssvr25.news.prodigy.net> Message-ID: Date: Tue, 04 Apr 2006 03:04:12 GMT Cecil Moore wrote: > Tom Donaly wrote: > >> If it disappears, you've done something wrong. > > > There is no phase information in standing wave phase, Tom. > I can't find it, Gene fuller can't find it, Eugene Hecht > can't find it, and James Clerk Maxwell can't find it. > > Any and all phase information in the standing wave phase > disappears during superposing. > > Let me give you another example. Assume that we superpose > one amp of DC current flowing in one direction and one > amp of DC current flowing in the other direction. What > does the superposed amplitude tell us about the amplitudes > of the superposed currents? Nothing, except they were > equal. Your idea of phase is to compare amplitudes at two separate places on the same wave and noting the time difference in behavior. You're right, you get the same "phase" if you do that to a standing wave in a lossles medium. You're not right, however, in thinking that the phase difference between two waves travelling in different directions down a transmission line can never be known. But as I wrote before, that isn't what you should be after. You should want to know the Beta*l of the coil on your antenna so you'll know its electrical length. And you can know it if it is true that you can model a coil as a simple transmission line. That's a big if, but it's something you should have thought of before you shot off your mouth. 73, Tom Donaly, KA6RUH Article: 223091 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Coils and Transmission Lines. References: <3gSXf.63583$Jd.40227@newssvr25.news.prodigy.net> Message-ID: <_slYf.64140$Jd.21145@newssvr25.news.prodigy.net> Date: Tue, 04 Apr 2006 03:10:50 GMT Tom Donaly wrote: > You should want to know the Beta*l of > the coil on your antenna so you'll know its electrical length. The discussion is no longer about coils. It's clear that a lot of posters don't understand the nature of standing waves. If they don't understand standing waves in a transmission line or on a wire, they cannot possibly understand standing waves on a coil. -- 73, Cecil http://www.qsl.net/w5dxp Article: 223092 of rec.radio.amateur.antenna From: richardharrison@webtv.net (Richard Harrison) Subject: Re: Coils and Transmission Lines. Date: Mon, 3 Apr 2006 21:47:55 -0600 Message-ID: <11762-4431EC6B-1061@storefull-3252.bay.webtv.net> References: Tom Donaly, KA6RUH wrote: ""---first you have to find out what phase means in a standing wave transmission line." Cecil knows very well what phase means in a transmission line. Terman describes it best for me, but it would be best to have his book with all his diagrams which makes his explanation of how standing waves are established simple indeed. Terman writes on page 89 of his 1955 edition: "Transmission line with Open-Circuited Load." (This is related to the standing-wave antenna which also ends up with an open-circuit load.) "When the load impedance is infinite, Eq.(4-14) (This gives the reflection coefficient rho as the vector ratio of the reflected wave to the incident wave at the load) shows that the coefficient of reflecftion will be 1 on an angle of zero. Under these conditions the incident and reflected waves (voltages) will have the same phase. As a result, the voltages of the two waves add arithmetically so that at the load E1 = E2 = EL/2. (Voltage doubles at the open circuit.) Under these conditions it follows from Eqs. (4-8) (Eforward/Iforward=Zo) and (4-11) (Ereflected / Ireflected=-Zo) that the currents of the two waves are equal in magnitude but opposite in phase; they thus add up to zero load current, as must be the case if the load is open-circuited. Consider now how these two waves behave as the distance l from the load increases. The incident wave advances in phase beta radians per unit length, while the reflected wave lags correspondingly; at the same time magnitudes do not change greatly when the attenuation-constant alpha is small. The vector sum of the voltages of the two waves is less than the arithmetic sum, as illustrated in Fig. 4-3a, for l=lambda/8. This tendency continues until the distance to the load becomes exactly a quarter wavelength, i.e.,until beta l = pi/2. The incident wave has then advanced 90-degrees from its phase position at the load, while the reflected wave has dropped back a similar amount. The line voltage at this point is thus the arithmertic difference of the voltages of the two waves, as shown in Fig. 4-3a, for l=lambda/4 and it will be quite small if the attenuation is small. The resultant voltage will not be zero, however, because some attenuation will always be present, and this causes the incident wave to be larger and the reflected wave to be smaller at the quarter-wave length point than at the load, where the amplitudes are exactly the same." This is enough of Terman`s desctiption to establish the pattern of SWR. He describes simply but not too simply. Almost anything anyone would want to know is in the book. The illustrations are worth thousands of words. Anytime I have any doubt about radio, Terman can straighten me out. Best regards, Richard Harrison, KB5WZI Article: 223093 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Current across the antenna loading coil - from scratch References: <1143142526.021154.67050@e56g2000cwe.googlegroups.com> <1144062834.591149.121920@v46g2000cwv.googlegroups.com> <69aYf.63812$Jd.56966@newssvr25.news.prodigy.net> <1fWdnQLbJqyMyqzZnZ2dnUVZ_smdnZ2d@adelphia.com> <0veYf.11366$tN3.1035@newssvr27.news.prodigy.net> <8redneWq1um7A6zZRVn-iw@adelphia.com> Message-ID: Date: Tue, 04 Apr 2006 04:41:26 GMT John Popelish wrote: > Cecil Moore wrote: >> Compared to zero amps of standing wave current when the forward current >> phasor and the reflected current phasor are 180 degrees out of phase, >> just how much effect can capacitance have? > > A standing wave voltage passes exactly as much (AC RMS) current through > a capacitance as a traveling wave voltage does. But the two waves are different as can be seen from their equations. A traveling wave transfers net energy along a transmission line or antenna wire. A standing wave transfers zero net energy along a transmission line or antenna wire. From "Fields and Waves in Modern Radio", by Ramo & Whinnery, 2nd edition, page 43: "The total energy in any length of line a multiple of a quarterwavelength long is constant, merely interchanging between energy in the electric field of the voltages and energy in the magnetic field of the currents." Hecht says it best in "Optics" concerning standing waves: "The composite disturbance is then: E = Eo[sin(kx+wt) + sin(kx-wt)] Applying the identity: sin A + sin B = 2 sin 1/2(A+B)*cos 1/2(A-B) yields: E(x,t) = 2*Eo*sin(kx)*cos(wt)" "This is the equation for a STANDING or STATIONARY WAVE, as opposed to a traveling wave. Its profile does not move through space; it is clearly not of the form Func(x +/- vt)." [Standing wave phase] "doesn't rotate at all, and the resultant wave it represents doesn't progress through space - its a standing wave." Speaking of "... net transfer of energy, for the pure standing wave there is none." -- 73, Cecil http://www.qsl.net/w5dxp Article: 223094 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Current across the antenna loading coil - from scratch References: <1143142526.021154.67050@e56g2000cwe.googlegroups.com> <1144062834.591149.121920@v46g2000cwv.googlegroups.com> <69aYf.63812$Jd.56966@newssvr25.news.prodigy.net> <1fWdnQLbJqyMyqzZnZ2dnUVZ_smdnZ2d@adelphia.com> <0veYf.11366$tN3.1035@newssvr27.news.prodigy.net> <8redneWq1um7A6zZRVn-iw@adelphia.com> <1144111853.486784.119070@i39g2000cwa.googlegroups.com> <1233ji3112ktg52@corp.supernews.com> <1144121237.437722.6580@t31g2000cwb.googlegroups.com> Message-ID: <2UmYf.55240$F_3.33995@newssvr29.news.prodigy.net> Date: Tue, 04 Apr 2006 04:47:58 GMT K7ITM wrote: > The reason you need to do this for me to even begin to believe you have > any idea what you are talking about is that you have rejected out of > hand some very fundamental concepts that I've put numbers on for you. I've rejected your obvious attempts at logical diversions. > Lay it on us, Cecil. Start with the fundamentals. And don't be > dragging out that tired old travelling-waves/standing-waves stuff till > you've established that you actually can even have waves, and just what > it is that governs their behaviour. :-) Just one more attempt at a logical diversion. I think we can all assume that EM waves exist and are capable of propagating along a transmission line, or antenna wire, or even in free space, e.g. light. What we cannot assume is that standing waves move or progress through space (or wire). Eugene Hecht says they don't. -- 73, Cecil http://www.qsl.net/w5dxp Article: 223095 of rec.radio.amateur.antenna From: "Tom Donaly" Subject: Re: Coils and Transmission Lines. References: <3gSXf.63583$Jd.40227@newssvr25.news.prodigy.net> <_slYf.64140$Jd.21145@newssvr25.news.prodigy.net> Message-ID: <%xoYf.8255$4L1.5002@newssvr11.news.prodigy.com> Date: Tue, 04 Apr 2006 06:40:59 GMT Cecil Moore wrote: > Tom Donaly wrote: > >> You should want to know the Beta*l of >> the coil on your antenna so you'll know its electrical length. > > > The discussion is no longer about coils. It's clear that a > lot of posters don't understand the nature of standing waves. > If they don't understand standing waves in a transmission > line or on a wire, they cannot possibly understand standing > waves on a coil. Well, Cecil, you've certainly shown your knowledge is weak in this area. You can improve the general knowledge by being the first to crack the books. 73, Tom Donaly, KA6RUH Article: 223096 of rec.radio.amateur.antenna From: "Tom Donaly" Subject: Re: Current across the antenna loading coil - from scratch References: <1143142526.021154.67050@e56g2000cwe.googlegroups.com> <1144062834.591149.121920@v46g2000cwv.googlegroups.com> <69aYf.63812$Jd.56966@newssvr25.news.prodigy.net> <1fWdnQLbJqyMyqzZnZ2dnUVZ_smdnZ2d@adelphia.com> <0veYf.11366$tN3.1035@newssvr27.news.prodigy.net> <8redneWq1um7A6zZRVn-iw@adelphia.com> Message-ID: Date: Tue, 04 Apr 2006 06:59:26 GMT Cecil Moore wrote: > John Popelish wrote: > >> Cecil Moore wrote: >> >>> Compared to zero amps of standing wave current when the forward current >>> phasor and the reflected current phasor are 180 degrees out of phase, >>> just how much effect can capacitance have? >> >> >> A standing wave voltage passes exactly as much (AC RMS) current >> through a capacitance as a traveling wave voltage does. > > > But the two waves are different as can be seen from their > equations. A traveling wave transfers net energy along a > transmission line or antenna wire. A standing wave transfers > zero net energy along a transmission line or antenna wire. > > From "Fields and Waves in Modern Radio", by Ramo & Whinnery, > 2nd edition, page 43: "The total energy in any length of line > a multiple of a quarterwavelength long is constant, merely > interchanging between energy in the electric field of the > voltages and energy in the magnetic field of the currents." > > Hecht says it best in "Optics" concerning standing waves: > > "The composite disturbance is then: > > E = Eo[sin(kx+wt) + sin(kx-wt)] > > Applying the identity: > > sin A + sin B = 2 sin 1/2(A+B)*cos 1/2(A-B) > > yields: > > E(x,t) = 2*Eo*sin(kx)*cos(wt)" > > "This is the equation for a STANDING or STATIONARY WAVE, as opposed > to a traveling wave. Its profile does not move through space; it is > clearly not of the form Func(x +/- vt)." > > [Standing wave phase] "doesn't rotate at all, and the resultant > wave it represents doesn't progress through space - its a standing > wave." > > Speaking of "... net transfer of energy, for the pure standing > wave there is none." Cecil, how can you quote Hecht when you don't have the foggiest notion what he's talking about? Here's a more general equation for you Cecil: (A1-A2)*Cos(wt-kx) + 2*A2*Cos(kx+d/2)*Cos(wt+d/2). Do you have any idea what it should represent? Does it satisfy the wave equation? Does it represent anything real? Sit and think about it before you get hysterical. 73, Tom Donaly, KA6RUH Article: 223097 of rec.radio.amateur.antenna From: Silfax Subject: Re: paint antenna? References: <122u6ah1aa5iv2e@corp.supernews.com> Message-ID: Date: Tue, 04 Apr 2006 12:08:26 GMT >> Dave WD9BDZ > > the bricks have been recently waterproffed, thou i guess they will still > be soggy after a strong rain guess i'd just have to add a small amount > of paint, and keep painting till swr etc are where it need to be to make > resonant if it even works > > sounds like a fun experiment can't wait to snag some paint If you paint a yagi on the roof, how do you intend on rotating the building? Article: 223098 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Current across the antenna loading coil - from scratch References: <1143142526.021154.67050@e56g2000cwe.googlegroups.com> <0hf13258667d7d0m648bf6rbgm6ecrj2sl@4ax.com> <5qaYf.6$qO.0@fe10.lga> <1144131328.322721.32520@t31g2000cwb.googlegroups.com> Message-ID: Date: Tue, 04 Apr 2006 12:27:01 GMT nm5k@wt.net wrote: > I just don't see the facination with arguing about something that even > if > decided one way or the other, still won't make any difference in the > final > antenna design. The sun still rises every morning whether it is caused by the earth's rotation or by the Sun God riding his chariot across the sky. The facination is called technical correctness. -- 73, Cecil http://www.qsl.net/w5dxp Article: 223099 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Coils and Transmission Lines. References: <3gSXf.63583$Jd.40227@newssvr25.news.prodigy.net> <_slYf.64140$Jd.21145@newssvr25.news.prodigy.net> <%xoYf.8255$4L1.5002@newssvr11.news.prodigy.com> Message-ID: Date: Tue, 04 Apr 2006 12:36:30 GMT Tom Donaly wrote: > Cecil Moore wrote: >> The discussion is no longer about coils. It's clear that a >> lot of posters don't understand the nature of standing waves. >> If they don't understand standing waves in a transmission >> line or on a wire, they cannot possibly understand standing >> waves on a coil. > > Well, Cecil, you've certainly shown your knowledge is weak in > this area. You can improve the general knowledge by being the > first to crack the books. The nature of standing waves is not a difficult subject. Some people have a single particular misconception about standing waves that have lead them to technically incorrect conclusions about standing wave antennas. In fact, before I brought up the subject, it appeared they didn't even realize that a mobile antenna is a standing wave antenna. Given a lossless, unterminated transmission line, with two black boxes located at points along the line. Source-----------a-BBox-b-------------c-BBox-d-----------open The current at 'a' is one amp and the current at 'b' is zero The current at 'c' is zero and the current at 'd' is one amp What's in the black boxes? -- 73, Cecil http://www.qsl.net/w5dxp Article: 223100 of rec.radio.amateur.antenna From: "Richard Fry" References: <0hf13258667d7d0m648bf6rbgm6ecrj2sl@4ax.com> <11783-4431A0B7-956@storefull-3254.bay.webtv.net> Subject: Re: Current across the antenna loading coil - from scratch Date: Tue, 4 Apr 2006 07:36:35 -0500 Message-ID: <44326790_1@newsfeed.slurp.net> "Richard Harrison" wrote: > It is the convention to describe AM broadcast towers in electrical > degrees. Harold Ennes reprints an RCA resistance chart for heights > between 50 and 200 degrees in "AM-FM Broadcast Maintenance". > > Formula given is: > Height in electrical degrees = Height in feet X frequency in kc X > 1.016 X 10 to the minus 6 power. _______________ If electrical length is defined as the physical condition where feedpoint reactance is zero (e.g., resonance), then the true electrical length of an AM broadcast radiator on a given frequency is a function of the physical length AND physical width of that radiator. This was proven experimentally, and documented by George Brown of RCA Labs in his paper "Experimentally Determined Impedance Characteristics of Cylindrical Antennas" published in the Proceedings of the I.R.E. in April, 1945. It also has been proven in thousands of independent measurements of AM broadcast radiators ever since. The curves in Figure 3 of Brown's paper show the feedpoint reactance terms of the base impedance of an unloaded monopole of various lengths and widths, working against a nearly perfect ground plane. Those values cross the zero reactance axis at physical heights ranging from about 80 degrees (for the widest radiator) to about 86 degrees for the most narrow. Brown calculated height in degrees as (Physical Height in feet x Frequency in kHz ) / 2725 . Brown's equation, the one in the Harold Ennes quote above, and the one that the FCC uses in their published data all define only the relationship of the physical length of the radiator to its free-space wavelength in degrees at that frequency. But clearly these lengths in degrees do not define the self-resonant length of that radiator. The self-resonant length, invariably, will be shorter by several percent. This fact is easily confirmed by simple NEC models, for those who want to probe into George Brown's data. Tables relating a single value of base impedance as typical for towers of various electrical heights (only) must be read with an understanding of the above realities. For example, Ennes' list shows a tower of 90 electrical degrees to have zero reactance. But Brown's 1945 paper and a great amount of later field experience shows that this is incorrect, for the conventional use of this term. RF Article: 223101 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Current across the antenna loading coil - from scratch References: <1143142526.021154.67050@e56g2000cwe.googlegroups.com> <1144062834.591149.121920@v46g2000cwv.googlegroups.com> <69aYf.63812$Jd.56966@newssvr25.news.prodigy.net> <1fWdnQLbJqyMyqzZnZ2dnUVZ_smdnZ2d@adelphia.com> <0veYf.11366$tN3.1035@newssvr27.news.prodigy.net> <8redneWq1um7A6zZRVn-iw@adelphia.com> <1144111853.486784.119070@i39g2000cwa.googlegroups.com> <1144138016.208612.21220@i39g2000cwa.googlegroups.com> Message-ID: Date: Tue, 04 Apr 2006 12:50:29 GMT w8ji@akorn.net wrote: > Cecil Moore wrote: >>Time to stop the ad hominem attacks and address this technical issue. > > When you show a track record of being honest and you stop those attacks > and your constant distortions of what other people say, I'm sure people > will start talking to you again. So by demonizing me, you avoid any technical discussion that might prove you wrong. That's pretty transparently obvious, Tom. -- 73, Cecil http://www.qsl.net/w5dxp Article: 223102 of rec.radio.amateur.antenna From: "hasan schiers" Subject: Re: HDTV Antennas Date: Tue, 4 Apr 2006 09:23:38 -0500 Message-ID: References: Dick, Since the vast majority of HDTV channels are on UHF, make sure that you have good UHF performance. If using an outside antenna, and you do other OTA viewing, you might as well get a good one that covers VHF/UHF. I particularly like the Channel Master antennas with boom lengths anywhere >from 6 to 10 feet. In most cases there is no such thing as too much signal. Of course, if you are really close to the transmit towers, you can get exactly that. As far as a "simple" antenna...you may find that you have multi-path problems with them. Lots of variables to consider, but none of them have anything in particular to do with HDTV . Your best bet is to go to the antennaweb site, plug in your zip code or location and see what antenna they recommend. This site is used by a lot of HDTV enthusiasts. www.antennaweb.org 73, ...hasan, N0AN "aRKay" wrote in message news:REMOVEarkay-20B980.20430403042006@newsclstr02.news.prodigy.com... > What is unique about the new HDTV antennas? We just picked up a new > HDTV with a tuner and was advised to pickup a simple HDTV antenna to > pick up the local digital broadcast. Any magic to these other the high > gain claims on the boxes? > > Dick AA5VU Article: 223103 of rec.radio.amateur.antenna From: "Yuri Blanarovich" References: <1143142526.021154.67050@e56g2000cwe.googlegroups.com> <0hf13258667d7d0m648bf6rbgm6ecrj2sl@4ax.com> <5qaYf.6$qO.0@fe10.lga> <1144131328.322721.32520@t31g2000cwb.googlegroups.com> Subject: Re: Current across the antenna loading coil - from scratch Message-ID: Date: Tue, 4 Apr 2006 10:32:08 -0400 wrote in message news:1144131328.322721.32520@t31g2000cwb.googlegroups.com... > >but we can not >>use electrical degrees to 'splain the behavior of coiled antenna wire? > > I can see how problems could arise going by the length of coil > wire length in degrees only. Lets say you run a coil 1 foot from the > base. Lets say that coil uses 25 turns to tune a particular frequency. > Now, move the coil up 2 ft higher, and see if that same 25 turns will > tune the same frequency. It won't. You will have to add a few more > turns. > So just going by the total mast plus coil wire length in degrees could > vary > all over the map just by changing the position of the coil. As you > raise > the coil, you will have to add more and more of "degrees" of wire to > tune the same frequency. :/ > Dunno...There may well be some variation of current from the bottom > vs the top of the coil, but overall, I still view the operation of a > loading > coil as a "lumped" mechanism overall. > Even if you all decide that the current changes, or it doesn't , it > ain't > gonna make a hoot's worth of difference in the design of mobile whips. > I think it's an argument that has no real value to me as far as mobile > whips go. The performance of all the various coil heights, and configs > have been well known for years. Coil current taper or not. > I just don't see the facination with arguing about something that even > if > decided one way or the other, still won't make any difference in the > final > antenna design. Oh well...Continue the tail chasing excercise.... > I'm outa this one... One post is all I will waste on this subject.. > I couldn't mount my coil much higher if I wanted to... Current taper or > not. :/ > MK > MK, that is the whole point, that you portray missing or not appreciating. It might not matter to you if you lose $100, but it might matter to someone else. Same with loading coil. What you are describing, the effect where the coil is located, being known, is the result of the phenomena we are trying to straighten out, explain and apply properly in modeling and design exercises. The position of coil within the antenna has significant effect. The worst is at the base, fewer turns required. The best is somewhere about 2/3 up the radiator, more turns required. You stick it on the top, no stinger or hat, you get it almost invisible. With what we are discussing and defending here is the proper understanding of the current flow in the loading coil and its drop across and its effect on the efficiency of the loaded antenna. Efficiency is proportional to the area under the current curve distribution along the radiator. If you properly model the coil as solenoid or loading stub to see the real drop of current across the coil and its effect in various positions along the radiator, the all is clear and is with agreement with practical experience, antenna shootout results, measurements. As I mentioned numerous times, its effect on design and modeling loaded antenna systems will be even more pronounced, because effect gets magnified when you start adding elements. This is especially important when you try to design super receiving antennas for low bands where F/B and clean pattern is very desirable and is the most critical aspect of antenna design or modeling. It is harder to obtain the max F/B or least rear lobes than to maximize the design for max gain. It might not matter to you, but I am sure many would benefit from knowing more precisely what is REALLY going on and then use or correct their design methodology. I think it is fine for you to ignore this and poh-poh it. But I know how huge difference it made in my 160m mobile antenna when I extended the whip to the front bumper with wire. We are not saying that piece of wire that coil is wound with, has so many electrical degrees. If we carefully consider and understand the phenomena, you would realize that the radiator has same electrical length (say 15 deg) and when you move the coil and ADJUST THE TURNS to bring the antenna back to resonance (90 deg) that coil would "replace, take care of" 75 degrees. The turns have to be adjusted in order to "participate" in the current replacement game. The lesson is, the higher you place the coil on the radiator, the more turns you need to reresonate the radiator, the high current portion of the antenna current distribution curve gets "stretched up", better efficiency (larger area under the overall curve). Then the coil DROPS the current across itself to some lower value, which then continues to drop across the tip and that area, quite smaller adds to the one from the bottom part of the radiator. This all is supported by reality, except "gurus" who insist that the current is (about) the same across the coil and they make (theoretically) antenna current to be higher across the tip and "more" efficient than it is. Again, you stick 6 of those in the 3 el loaded Yagi design and you get GI-GO. It is known how profound effect had replacement of loading stubs by coils in the KLM 3 el. 80 m loaded Yagi. Better gain, huge improvement in the F/B and pattern. Has been done and described. And this is just replacing the same inductance value stub with coil, where delta current from stub wires was enough to throw monkey wrench in the Yagi performance. Now consider larger error from the wrong assumption or calculation caused by wrong current magnitudes and distribution. Again you might not give a hoot about this "trivial" exercise, but if I want to design 4 el loaded quad or Yagi for 80 or 160, it matters a lot. So it just amazes me that some of the smarter heads resist so much in trying to find out reality and develop better consideration of the effect for design and modeling. No technical answers to Cecil's questions and my "from scratch" thread deteriorated into pink electrons and dead end in electrical degrees. So far what we have is the reality, few who are trying to legitimize it and few who got off on the wrong foot, in effort to preserve their (wrong) face they cling to it with scientwific "proofs" why it can't be so, when IT IS. When I tried to go step by technical step through the case, the "gurus" are not there. Cases that Cecil showed in EZNEC model and demonstrating that current across the loading coil (not one in the box) in the antenna can have anything from equal to "nothing" at the other end, depending on its position in the standing wave picture. It all jives with our original argument. We spotted the "problem", we dissected it, thanks to fierce flat earthers, and now have better understanding of the phenomena and can use to design better antennas. I care about antennas, this is the last frontier where we can still improve thing, now with modeling tools. I still operate contests and go for ultimate - beating the all time records, and that's where the edge can be obtained. Heloooo guys! Measure, feel, whatever, the frickin' current across the loading coil and then come back and tell the world why it IS different, but IT CAN'T be so, because you said so in the beginning and you just can't admit being wrong. Reality can't be twisted, just like Earth is not going back to flat! Saying now that is no big deal, not important, will not exonerate the "wrongoes". It is significant not to be ignored. If I was in "their" shoes, I would say: "gee guys, interesting, thanks for bringing it up, explaining it, I guess we were wrong, now we can design better antennas". Stay tuned..... Thanks again Cecil, Richard and others for putting up with and shedding more and more light on the phenomena. It must go down in history as big as Galileo's fight :-) I am glad that, hopefully, nobody will burn us. 73 Yuri, K3BU.us Article: 223104 of rec.radio.amateur.antenna From: "Richard Fry" References: <0hf13258667d7d0m648bf6rbgm6ecrj2sl@4ax.com> <11783-4431A0B7-956@storefull-3254.bay.webtv.net> <44326790_1@newsfeed.slurp.net> Subject: Re: Current across the antenna loading coil - from scratch Date: Tue, 4 Apr 2006 11:20:31 -0500 Message-ID: <44329c0a_2@newsfeed.slurp.net> "Cecil Moore" wrote ... > Richard Fry wrote: >> But clearly these lengths in degrees do not define the self-resonant >> length of that radiator. > > Could it be that the resonant 80 degrees of physical length > is 90 degrees of electrical length? __________ That a self-resonant, unloaded broadcast radiator length is shorter than the 90 degree conventional "electrical length" defined by the FCC is a given. But this reality sometimes is not recognized. RF Article: 223105 of rec.radio.amateur.antenna From: "Tom Donaly" Subject: Re: Current across the antenna loading coil - from scratch References: <1143142526.021154.67050@e56g2000cwe.googlegroups.com> <1144062834.591149.121920@v46g2000cwv.googlegroups.com> <69aYf.63812$Jd.56966@newssvr25.news.prodigy.net> <1fWdnQLbJqyMyqzZnZ2dnUVZ_smdnZ2d@adelphia.com> <0veYf.11366$tN3.1035@newssvr27.news.prodigy.net> <8redneWq1um7A6zZRVn-iw@adelphia.com> Message-ID: Date: Tue, 04 Apr 2006 16:38:48 GMT Cecil Moore wrote: > Tom Donaly wrote: > >> Here's a more general equation for you Cecil: >> (A1-A2)*Cos(wt-kx) + 2*A2*Cos(kx+d/2)*Cos(wt+d/2). > > > Yes, it is more general, Tom, but since the subject is standing > waves and not traveling waves, it is overly general. Why would > you post an equation containing a traveling wave term when the > subject is the equation for standing waves? > > This is the total equation for the condition where power is > being delivered to a load in the presence of standing waves. > The first term makes it to the load. The second term doesn't. > > The first term is a traveling wave and indeed does contain > phase information. There's no argument about whether a > traveling wave contains phase information. > > The argument is whether the second term, the standing wave > term, contains phase information. Gene Fuller says it doesn't, > Eugene Hecht says it doesn't, and I'm inclined to agree. Cecil, I won't try to educate you because it's a waste of time, but for everyone else, consider that in an antenna, there is energy going into, and being radiated out of, the antenna in the form of an electromagnetic wave. Since Cecil says standing waves can't transfer energy from one place to another (he didn't always say this) that means that the only way energy can be radiated is through the traveling wave component of the electromagnetic wave. You would think that this would be important to him in his search for a dumbed down theory of reflection mechanics, but evidently he is more interested in his arguing point concerning Tom R. and Roy measuring current in a standing wave environment than he is in reaching an understanding of what he's talking about. No wonder no one's communicating with him. 73, Tom Donaly, KA6RUH Article: 223106 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Current across the antenna loading coil - from scratch References: <1143142526.021154.67050@e56g2000cwe.googlegroups.com> <1144062834.591149.121920@v46g2000cwv.googlegroups.com> <69aYf.63812$Jd.56966@newssvr25.news.prodigy.net> <1fWdnQLbJqyMyqzZnZ2dnUVZ_smdnZ2d@adelphia.com> <0veYf.11366$tN3.1035@newssvr27.news.prodigy.net> <8redneWq1um7A6zZRVn-iw@adelphia.com> Message-ID: Date: Tue, 04 Apr 2006 16:42:08 GMT John Popelish wrote: > But at any point that is not a > node in the standing wave pattern, there will be an ordinary AC voltage > or current at some amplitude between double the traveling wave amplitude > and zero amplitude, and one of two phases (that switch each time you > pass a node). Please give us the equation for "ordinary AC voltage or current". > No argument. But a standing wave still represents storage of energy in > the line, as with any resonant structure, and that stored energy shows > up as magnetic fields and electric fields along the line. The big > difference is that the magnetic fields bob up and down at some areas and > the electric fields bob up and down half way in between those areas. At > any given moment, there is a fixed total energy in the combination of > all the magnetic and electric fields. No argument, and therefore no need for the "But" in your statement. I agree with you but it doesn't change a thing about the real argument. > Exactly. How can you write this, but deny the capacitive current that > delivers this electric field energy twice every cycle to all capacitance > feeling this voltage swing? I don't deny it - never have - never will. Please stop trying to set up straw men. The discussion has *NEVER* be about what happens during one cycle. The current measured by W8JI and W7EL and reported by EZNEC is RMS current. Instantaneous values are just another straw man diversion. > Profiles do not charge capacitance, ... I'm glad you agree. Profiles are maximum RMS envelope values and that is what EZNEC reports. >> [Standing wave phase] "doesn't rotate at all, and the resultant >> wave it represents doesn't progress through space - its a standing >> wave." > > I suggest you drop talking about phasors, till you understand what cos(wt). Hecht and I have been a little lose with words while assuming the readers have a certain knowledge level. For the uninitiated, When Hecht (or I) say the phasor doesn't rotate at all, we mean the phasor doesn't rotate at all with respect to the source phasor. Any initiated person would know that. The phase of the standing waves doesn't change with respect to the phase of the source signal. Hecht assumed you would know what he meant by that statement. >> Speaking of "... net transfer of energy, for the pure standing >> wave there is none." > > A standing wave does not violate conservation of energy. Exactly my point! Nothing violates conservation of energy. If the RMS forward current in the coil is the same magnitude at both ends and the RMS reflected current in the coil is the same at both ends, the conservation of energy principle is satisfied NO MATTER WHAT THE STANDING WAVE CURRENT TURNS OUT TO BE. What is it about that statement that you don't understand? > Storage that must continuously be swapping back and forth from magnetic > field energy to electric field energy. When the energy storage is all > electric, that implies charges capacitance. Again, nobody has ever been discussing what happens within a partial cycle. Discussion of such is obviously a diversionary straw man. Feel free to find someone else willing to discuss it. It is completely irrelevant to this discussion of RMS envelope values. -- 73, Cecil http://www.qsl.net/w5dxp Article: 223107 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Current across the antenna loading coil - from scratch References: <0hf13258667d7d0m648bf6rbgm6ecrj2sl@4ax.com> <11783-4431A0B7-956@storefull-3254.bay.webtv.net> <44326790_1@newsfeed.slurp.net> <44329c0a_2@newsfeed.slurp.net> Message-ID: Date: Tue, 04 Apr 2006 16:54:50 GMT Richard Fry wrote: > "Cecil Moore" wrote ... >> Could it be that the resonant 80 degrees of physical length >> is 90 degrees of electrical length? > > That a self-resonant, unloaded broadcast radiator length is shorter than > the 90 degree conventional "electrical length" defined by the FCC is a > given. But this reality sometimes is not recognized. For instance, EZNEC says a 33 ft. vertical made of #30 wire is resonant on 7.265 MHz while a one foot diameter pipe is resonant on 6.9 MHz. Does the FCC define physical lengths or electrical lengths? -- 73, Cecil http://www.qsl.net/w5dxp Article: 223108 of rec.radio.amateur.antenna From: "Richard Fry" References: <0hf13258667d7d0m648bf6rbgm6ecrj2sl@4ax.com> <11783-4431A0B7-956@storefull-3254.bay.webtv.net> <44326790_1@newsfeed.slurp.net> <44329c0a_2@newsfeed.slurp.net> Subject: Re: Current across the antenna loading coil - from scratch Date: Tue, 4 Apr 2006 12:11:20 -0500 Message-ID: <4432a7f4_5@newsfeed.slurp.net> "Cecil Moore" > Does the FCC define physical lengths or electrical lengths? ____________ They call it an electrical length, but calculate it as the number of free-space electrical degrees contained in the physical length of the radiating structure, at the carrier frequency. So really, FCC "electrical length" is a measure of a physical length, not of an effective electrical length. The effective electrical length of a MW monople radiator determines its resonant frequencies, and that must include the velocity of propagation along the structure -- which is a function of the height AND width of the radiator (mainly), and the operating frequency. RF Article: 223109 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Current across the antenna loading coil - from scratch References: <1143142526.021154.67050@e56g2000cwe.googlegroups.com> <1144062834.591149.121920@v46g2000cwv.googlegroups.com> <69aYf.63812$Jd.56966@newssvr25.news.prodigy.net> <1fWdnQLbJqyMyqzZnZ2dnUVZ_smdnZ2d@adelphia.com> <0veYf.11366$tN3.1035@newssvr27.news.prodigy.net> <8redneWq1um7A6zZRVn-iw@adelphia.com> Message-ID: Date: Tue, 04 Apr 2006 17:14:25 GMT Tom Donaly wrote: > Cecil, I won't try to educate you because it's a waste of time, but > for everyone else, consider that in an antenna, there is > energy going into, and being radiated out of, the antenna in the > form of an electromagnetic wave. That's true, but compared to the standing waves, it is pretty small. In fact, when Kraus talks about a 1/2WL thin-wire dipole, he completely ignores the traveling wave and energy "lost" as radiation and assumes the forward wave and reflected wave have the same magnitude. If you want to argue that trivial point, take it up with Kraus. Here's what he says: "It is generally assumed that the current distribution of an infinitesimally thin antenna is sinusoidal, and that the phase is constaant over a 1/2WL interval, changing abruptly by 180 degrees between intervals. That would only be true if the reflected wave was equal in magnitude to the forward wave, i.e. no loss due to radiation or I^2*R losses. If Kraus gives us permission to ignore the traveling wave for purposes of discussion, who are you to argue? I have calculated that there is only a 10% drop between forward voltage or current and the reflected voltage or current arriving back at the feedpoint for a 1/2WL dipole. For the sake of discussion of standing waves in standing wave antennas, with an accuracy within 10%, the loss due to radiation can be ignored according to Kraus. It's akin to ignoring the losses in a transmission line for the sake of discussion. > Since Cecil says standing waves > can't transfer energy from one place to another ... > sthat means that the only way energy can be radiated is > through the traveling wave component of the electromagnetic wave. Yes, that's true and since I have never said otherwise, this seems to be just another straw man. With an accuracy of about 10%, Kraus gives us permission to ignore the traveling wave in standing wave antennas for the purposes of discussion. -- 73, Cecil http://www.qsl.net/w5dxp Article: 223110 of rec.radio.amateur.antenna From: "hasan schiers" Subject: Re: HDTV Antennas Date: Tue, 4 Apr 2006 12:17:57 -0500 Message-ID: References: <1u55329agrpiremn6o4dgqjgbia9u48usj@4ax.com> Hi Richard, that's why I said "in most cases". I like your probablility metaphor. Doesn't sound like either one of us will be holding our breath. ...hasan, N0AN "Richard Clark" wrote in message news:1u55329agrpiremn6o4dgqjgbia9u48usj@4ax.com... > On Tue, 4 Apr 2006 09:23:38 -0500, "hasan schiers" > wrote: > >>In most cases there is no such thing as too much signal. > > Hi Hasan, > > In fact that is wrong. Too much signal can black out the picture. > > On the other hand, that is about as likely to happen as the borrow and > spend Republicans delivering a balanced budget. > > 73's > Richard Clark, KB7QHC Article: 223111 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Current across the antenna loading coil - from scratch References: <1143142526.021154.67050@e56g2000cwe.googlegroups.com> <1144062834.591149.121920@v46g2000cwv.googlegroups.com> <69aYf.63812$Jd.56966@newssvr25.news.prodigy.net> <1fWdnQLbJqyMyqzZnZ2dnUVZ_smdnZ2d@adelphia.com> <0veYf.11366$tN3.1035@newssvr27.news.prodigy.net> <8redneWq1um7A6zZRVn-iw@adelphia.com> <1144111853.486784.119070@i39g2000cwa.googlegroups.com> <1233ji3112ktg52@corp.supernews.com> <1144121237.437722.6580@t31g2000cwb.googlegroups.com> <2UmYf.55240$F_3.33995@newssvr29.news.prodigy.net> <1144169267.442808.52620@t31g2000cwb.googlegroups.com> Message-ID: Date: Tue, 04 Apr 2006 17:27:44 GMT K7ITM wrote: > You dismissed my honest, straightforward accounting of the > charge transport implied directly by the scenarios you set up. > In no way was it a "logical diversion." It was very much to the > point of explaining just WHY there is in fact a time delay through > your bugcatcher coil. The biggest clue that you are not arguing in good faith is that you trimmed out all the technical content and didn't quote anything I said. This posting of yours is disembodied from reality so you can demonize me and emote your angry gut feelings. Responses with no technical content and no quotes are an obvious attempt to obfuscate - so obfuscate away. It is possible I misunderstood what you were trying to say but unless you quote something of technical value, I will have no idea what my misunderstanding, if any, was all about. John P. seems to want to discuss instantaneous movement of energy. Why don't you two keep that discussion going? -- 73, Cecil http://www.qsl.net/w5dxp Article: 223112 of rec.radio.amateur.antenna From: Roy Lewallen Subject: Re: Current across the antenna loading coil - from scratch Date: Tue, 04 Apr 2006 12:07:28 -0700 Message-ID: <1235gvinaojtf1f@corp.supernews.com> References: <1143142526.021154.67050@e56g2000cwe.googlegroups.com> <1144062834.591149.121920@v46g2000cwv.googlegroups.com> <69aYf.63812$Jd.56966@newssvr25.news.prodigy.net> <1fWdnQLbJqyMyqzZnZ2dnUVZ_smdnZ2d@adelphia.com> <0veYf.11366$tN3.1035@newssvr27.news.prodigy.net> <8redneWq1um7A6zZRVn-iw@adelphia.com> I see that Cecil's latest fetish is that EZNEC reports RMS values of voltage and current. Because we know that the voltages and currents are purely sinusoidal, the RMS value and phase angle (also reported by EZNEC) are adequate to define the time waveform. That is, when we know the RMS amplitude and the phase angle, we know the value of the waveform at every instant in time. No additional information is necessary. Roy Lewallen, W7EL Article: 223113 of rec.radio.amateur.antenna From: "Ronnie" Subject: Question about auto antenna cable and connectors Message-ID: Date: Tue, 04 Apr 2006 19:17:12 GMT Hi, This is not about ham radio, but rather a general question about the type of cable and connectors that were found between the antenna and the AM radio in GM cars in the 60's. I'm trying to locate some technical information about the cable and a source for the cable and connectors. I have an old airplane autopilot system that uses tuned circuit to sense changes in the airplane's attitude and the position of the control servos. Distributed variable inductances and variable capacitors combine to establish the resonant operating frequency of the system. The components are connected together with specific lengths of cable and the service manual points out that the lengths are critical because of the added capacitance of the cable and connectors. The cable is marked as follows: "I. T. & T. Federal Cable R.E.C." It is a shielded cable with a spiral wound center conductor that looks very much like the antenna cable I remember finding in GM cars in the 60's. It also has the same type of connectors. There is a center pin for the center conductor and a metal sleve that extents back over the cable and makes a connection with the shield and chassis of the radio. Friction holds the connector in its mating socket - there are no threads, just a couple of splayed out areas on the sleve. I was hoping one of you might be able to point me to a source of technical information about this cable, such as the capacitance per unit length, etc. The one piece I have measures about 10.5 pF / foot or 415 pF / meter, but my measurements may not be all that accurate. Also, a source where the cable and connectors can be found today would be appreciated. Thanks in advance for any help. Ronnie, N5CSE Article: 223114 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Current across the antenna loading coil - from scratch References: <1143142526.021154.67050@e56g2000cwe.googlegroups.com> <1144062834.591149.121920@v46g2000cwv.googlegroups.com> <69aYf.63812$Jd.56966@newssvr25.news.prodigy.net> <1fWdnQLbJqyMyqzZnZ2dnUVZ_smdnZ2d@adelphia.com> <0veYf.11366$tN3.1035@newssvr27.news.prodigy.net> <8redneWq1um7A6zZRVn-iw@adelphia.com> Message-ID: Date: Tue, 04 Apr 2006 19:22:27 GMT John Popelish wrote: > Cecil Moore wrote: >> Please give us the equation for "ordinary AC voltage or current". > > The simplest (without a reference phase) would be cos(wt). The standing > wave function contains this term, with a modifier to tell you how > amplitude varies with position. But at any point, cos(wt) times some > amplitude describes the ordinary AC voltage or current swing. But please notice that cos(kx+wt) is different from that term. The only time they are the same is if 'x' = 0. Is 'x' always equal zero? No. All your equation tells us is that whatever current it represents, it is always in phase with the reference source at 'x' = 0. So your equation is too simple to be useful. Please try again. > EZNEC must take those within a cycle currents and voltages into account > to come up with the amplitude values. "Must" or "does". I have no idea. > At a given point the traveling wave phasor doesn't rotate, either. On the contrary - at any given point 'x', the traveling wave phasor is rotating with respect to the source phasor. That's what makes it different from a standing wave phasor which doesn't rotate with respect to the source phasor. > Phasor rotation only applies to the phase change over length for a > traveling wave. No, that's wrong. Take another look at cos(kx+wt). Holding 'x' at a constant value, the phase keeps on changing. The traveling wave phasor is rotating with respect to the source. The standing wave phasor is not rotating with respect to the source, just as Hecht says speaking of standing waves: "The resultant phasor is E1 + E2 = E ... Keeping the two [traveling wave] phasors tip-to-tail and having E1 rotate counterclockwise as E2 rotates (at the same rate) clockwise, generates E [total] as a function of 't'. ... It doesn't rotate at all, and the resultant wave it represents doesn't progress through space - it's a standing wave." You really need to get you a copy of Hecht's "Optics". It the best treatment of standing waves that I have ever seen - also best at superposition and interference explanations. > You don't add superposed RMS values to get the resultant RMS value. Sure you do. Current #1 is an RMS value at angle 1. Current #2 is an RMS value at angle 2. The superposition is: RMS#1*cos(A1) + RMS#2*cos(A2) = RMS(total) > There is no discussion of RMS envelope values. Where have you been? The currents displayed by EZNEC are RMS envelope values. The antenna currents plotted in Kraus and Terman are RMS envelope values. The currents measured at the top and bottom of the coils by W8JI and W7EK are RMS envelope values. > I am waiting for you to realize that you can measure the phase shift of > each of the traveling waves that superpose in a standing wave process > that includes a coil (or any other network) by using only the RMS > amplitude envelope, with no reference to phase, in an EZNEC simulation > or a real experiment. That was the whole point that began this > discussion, wasn't it? Yes, I said that months ago but nobody would buy the argument. Over those months, I have given countless examples proving that to be true. Everyone just ignored those technical facts as they have ignored 95% of the technical content of my postings only to concentrate on the 5% containing feelings or bad humor. > Now, measure the phase shift of that coil ... Sorry, the coil is obviously not the problem. Everyone understands how a coil works. What everyone doesn't understand is how standing waves in a wire work. That will be my topic of discussion from now on. But feel free to continue the coil topic with anyone else. -- 73, Cecil http://www.qsl.net/w5dxp Article: 223115 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Current across the antenna loading coil - from scratch References: <1143142526.021154.67050@e56g2000cwe.googlegroups.com> <1144062834.591149.121920@v46g2000cwv.googlegroups.com> <69aYf.63812$Jd.56966@newssvr25.news.prodigy.net> <1fWdnQLbJqyMyqzZnZ2dnUVZ_smdnZ2d@adelphia.com> <0veYf.11366$tN3.1035@newssvr27.news.prodigy.net> <8redneWq1um7A6zZRVn-iw@adelphia.com> <1144111853.486784.119070@i39g2000cwa.googlegroups.com> <1233ji3112ktg52@corp.supernews.com> <1144121237.437722.6580@t31g2000cwb.googlegroups.com> <2UmYf.55240$F_3.33995@newssvr29.news.prodigy.net> <1144169267.442808.52620@t31g2000cwb.googlegroups.com> <1144174480.860727.84680@g10g2000cwb.googlegroups.com> Message-ID: <%SzYf.64388$Jd.53946@newssvr25.news.prodigy.net> Date: Tue, 04 Apr 2006 19:34:19 GMT w8ji@akorn.net wrote: > Grow up Cecil. Everyone sees what you are doing. Everyone should see that I am trying to discuss technical issues while the rest of you object to the 5% of my postings that are bad humor or complaints about how I am being unfairly treated. Why do you refuse to discuss technical issues? For instance, you have avoided responding to my black box question. Are you afraid everyone will see just how wrong you are? Here is it again assuming a lossless transmission line: Source-----------a-BB-b-------------c-BB-d-----------open The current measured at 'a' is one amp. The current measured at 'b' is zero amps. The current measured at 'c' is zero amps. The current measured at 'd' is one amp. What are the possibilities for what could be in the black boxes? There could be 90 degrees of transmission line in each box. Or there could be 90 degree coils in each box. Or one box could contain 90 degrees of transmission line and the other contain 90 degrees of coil. -- 73, Cecil http://www.qsl.net/w5dxp Article: 223116 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Current across the antenna loading coil - from scratch References: <1143142526.021154.67050@e56g2000cwe.googlegroups.com> <1144062834.591149.121920@v46g2000cwv.googlegroups.com> <69aYf.63812$Jd.56966@newssvr25.news.prodigy.net> <1fWdnQLbJqyMyqzZnZ2dnUVZ_smdnZ2d@adelphia.com> <0veYf.11366$tN3.1035@newssvr27.news.prodigy.net> <8redneWq1um7A6zZRVn-iw@adelphia.com> <1235gvinaojtf1f@corp.supernews.com> Message-ID: Date: Tue, 04 Apr 2006 19:39:56 GMT Roy Lewallen wrote: > I see that Cecil's latest fetish is that EZNEC reports RMS values of > voltage and current. Because we know that the voltages and currents are > purely sinusoidal, the RMS value and phase angle (also reported by > EZNEC) are adequate to define the time waveform. That is, when we know > the RMS amplitude and the phase angle, we know the value of the waveform > at every instant in time. No additional information is necessary. Since you agree with me, what's with the fetish remark? You seem to feel obliged to take an ad hominem pot shot every time you mention my name. I assure you, it is hurting your reputation more than it is hurting mine. -- 73, Cecil http://www.qsl.net/w5dxp Article: 223117 of rec.radio.amateur.antenna From: Roy Lewallen Subject: Re: Current across the antenna loading coil - from scratch Date: Tue, 04 Apr 2006 12:54:33 -0700 Message-ID: <1235jnuqlvl9627@corp.supernews.com> References: <1143142526.021154.67050@e56g2000cwe.googlegroups.com> <1144062834.591149.121920@v46g2000cwv.googlegroups.com> <69aYf.63812$Jd.56966@newssvr25.news.prodigy.net> <1fWdnQLbJqyMyqzZnZ2dnUVZ_smdnZ2d@adelphia.com> <0veYf.11366$tN3.1035@newssvr27.news.prodigy.net> <8redneWq1um7A6zZRVn-iw@adelphia.com> <1235gvinaojtf1f@corp.supernews.com> Since EZNEC has been mentioned so much lately, it's appropriate to point out that it's able to calculate the current at all points along a helically modeled loading inductor with what I believe to be very good accuracy. And it does it without any use or knowledge of presumed traveling voltage or current waves. It deals only with the total current. Perhaps Cecil would benefit from investigating how this is done. EZNEC uses NEC-2 for calculations, and the NEC-2 manual is available on line at no cost. A detailed description of its methodology is presented in Part I. For those who want just a general overview of the method (the method of moments) in a more easily understood format, one can be found in the second and later editions of Kraus' _Antennas_. I notice that most newer antenna texts also include a description of the moment method, and it should be available in the web as well. Roy Lewallen, W7EL Article: 223118 of rec.radio.amateur.antenna From: "Richard Fry" References: <0hf13258667d7d0m648bf6rbgm6ecrj2sl@4ax.com> <11783-4431A0B7-956@storefull-3254.bay.webtv.net> <44326790_1@newsfeed.slurp.net> <44329c0a_2@newsfeed.slurp.net> <4432a7f4_5@newsfeed.slurp.net> <2eb5329scje915brj9gmb9sd17ejvcvm9t@4ax.com> Subject: Re: Current across the antenna loading coil - from scratch Date: Tue, 4 Apr 2006 15:02:11 -0500 Message-ID: <4432d00b_4@newsfeed.slurp.net> This is a multi-part message in MIME format. ------=_NextPart_000_0366_01C657F8.C0672950 Content-Type: text/plain; format=flowed; charset="iso-8859-1"; reply-type=original Content-Transfer-Encoding: 8bit Richard Clark wrote: > The FCC provides BOTH measurements. The correlation is obvious. > Any association between resonance, velocity of propagation, height, > width, etc. and something like our 118.60° tall antenna needs a heap > more explaining than resonance, velocity of propagation, height, width, > etc. ____________ That conclusion is in error, however. The FCC in fact calculates electrical length as I described: i.e., merely the number of free-space degrees in the physical length of the radiator at that carrier frequency. For confirmation, see the screen clip from the FCC's website calculation applet at the bottom of this post. The website for the FCC applet is http://www.fcc.gov/mb/audio/bickel/findvalues.html. The values in my screen clip cover your entry for WGOP. Your posted data for WGOP shows an 80.00 degree "electrical length" for a 125.2 meter tower on 540 kHz. The FCC applet shows 81.1857... electrical degrees for that height. The difference arises from the definitions of heights used by the FCC. The physical height in your FCC data is the overall height of the antenna structure above ground, including the base pier, base insulator and beacon. The calculation/translation to electrical height in degrees excludes those structures. For this reason the data for the other stations in your post also show the same effects. 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<1144062834.591149.121920@v46g2000cwv.googlegroups.com> <69aYf.63812$Jd.56966@newssvr25.news.prodigy.net> <1fWdnQLbJqyMyqzZnZ2dnUVZ_smdnZ2d@adelphia.com> <0veYf.11366$tN3.1035@newssvr27.news.prodigy.net> <8redneWq1um7A6zZRVn-iw@adelphia.com> <1235gvinaojtf1f@corp.supernews.com> <1235jnuqlvl9627@corp.supernews.com> Message-ID: Date: Tue, 04 Apr 2006 20:15:10 GMT Roy Lewallen wrote: > And it does it without any use or knowledge of presumed > traveling voltage or current waves. Thanks for the reference, Roy, I'll take a look at it. One wonders how EZNEC tells the difference between a standing wave antenna and a traveling wave antenna "without any use or knowledge of presumed traveling voltage or current waves". I'm willing to bet it doesn't use lumped circuit theory. :-) I'm also willing to bet that forward and reflected waves are taken care of in the equations used by NEC. -- 73, Cecil http://www.qsl.net/w5dxp Article: 223120 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Current across the antenna loading coil - from scratch References: <1143142526.021154.67050@e56g2000cwe.googlegroups.com> <1144062834.591149.121920@v46g2000cwv.googlegroups.com> <69aYf.63812$Jd.56966@newssvr25.news.prodigy.net> <1fWdnQLbJqyMyqzZnZ2dnUVZ_smdnZ2d@adelphia.com> <0veYf.11366$tN3.1035@newssvr27.news.prodigy.net> <8redneWq1um7A6zZRVn-iw@adelphia.com> <1144111853.486784.119070@i39g2000cwa.googlegroups.com> <1233ji3112ktg52@corp.supernews.com> <1144121237.437722.6580@t31g2000cwb.googlegroups.com> <2UmYf.55240$F_3.33995@newssvr29.news.prodigy.net> <1144169267.442808.52620@t31g2000cwb.googlegroups.com> <1144181113.412135.248850@t31g2000cwb.googlegroups.com> Message-ID: Date: Tue, 04 Apr 2006 20:18:26 GMT K7ITM wrote: > I beg your pardon? Excuse me? I "trimmed out all the technical > content and didn't quote anything you said"??? Yes, and you are doing it again. I'm quoting your entire posting and there is not one quote from me. > As a matter of fact, I > took exactly the numbers you gave us, ALL of them, and used them and > ONLY them in my accounting. If THAT's "disembodied from reality," then > I'd point out that it's YOUR numbers that are disembodied from reality. > In fact, I didn't argue with YOUR numbers at all. I just took them at > face value. You were the one that discarded what I carefully developed > from them without out so much as an ounce of reasoning or explanation. > After that I went on to FURTHER EXPLAIN why I had done what I did in > the first place, and you dismissed that again without any technical > explanation. > > It's all there for everyone to see, Cecil. If there's a quote from me in this posting, Tom, I am unable to find it. > Go ahead, dig yourself deeper into it. Since you didn't quote anything I said, I have no idea what you are talking about. -- 73, Cecil http://www.qsl.net/w5dxp Article: 223121 of rec.radio.amateur.antenna From: "Steve Nosko" Subject: Re: HDTV Antennas Date: Tue, 4 Apr 2006 14:50:55 -0500 Message-ID: References: <1u55329agrpiremn6o4dgqjgbia9u48usj@4ax.com> If that is the comparison, then everyone already has the black-out... buh dum dum. 73, Steve, K9DCI "Richard Clark" wrote in message news:1u55329agrpiremn6o4dgqjgbia9u48usj@4ax.com... > On Tue, 4 Apr 2006 09:23:38 -0500, "hasan schiers" > wrote: > > >In most cases there is no such thing as too much signal. > > Hi Hasan, > > In fact that is wrong. Too much signal can black out the picture. > > On the other hand, that is about as likely to happen as the borrow and > spend Republicans delivering a balanced budget. > > 73's > Richard Clark, KB7QHC Article: 223122 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Current across the antenna loading coil - from scratch References: <1143142526.021154.67050@e56g2000cwe.googlegroups.com> <1144062834.591149.121920@v46g2000cwv.googlegroups.com> <69aYf.63812$Jd.56966@newssvr25.news.prodigy.net> <1fWdnQLbJqyMyqzZnZ2dnUVZ_smdnZ2d@adelphia.com> <0veYf.11366$tN3.1035@newssvr27.news.prodigy.net> <8redneWq1um7A6zZRVn-iw@adelphia.com> <1144181514.142347.209790@v46g2000cwv.googlegroups.com> Message-ID: Date: Tue, 04 Apr 2006 20:42:50 GMT K7ITM wrote: > Cecil wrote, in reply to John P., > > "Of course, *everyone* except you and Tom Donaly are talking about > charge stored over a whole cycle." It sure would be nice if you made your attributions conform to netnews guidelines. I cannot tell what you are responding to since your attributions are all screwed up. > Excuse me??? > > Note Cecil's emphasis on "everyone". Note that this was posted AFTER I > had repeatedly told him that _I_ was not talking about 'charge stored > over a whole cycle'. I'm offended that Cecil would fail to acknowledge > me as not being in the "everyone" group. I'll let others speak for > themselves, but I'd put pretty good odds that several others will be > crystal clear about not being included in that "everyone." I obviously got my "Tom's" mixed up. There's three of you here and it's likely a common mistake. I profusely apologize and don't know what else I can do to rectify my mistake. If there were two Cecil's here and you got us mixed up, I wouldn't get my panties bunched into a wedgie because of that. -- 73, Cecil http://www.qsl.net/w5dxp Article: 223123 of rec.radio.amateur.antenna From: "Yuri Blanarovich" References: <1143142526.021154.67050@e56g2000cwe.googlegroups.com> <0hf13258667d7d0m648bf6rbgm6ecrj2sl@4ax.com> <5qaYf.6$qO.0@fe10.lga> <1144131328.322721.32520@t31g2000cwb.googlegroups.com> <1k5532h8scbtg8e8iscn4ncjuusoa7ddai@4ax.com> Subject: Re: Current across the antenna loading coil - from scratch Message-ID: Date: Tue, 4 Apr 2006 16:47:05 -0400 "Richard Clark" wrote in message news:1k5532h8scbtg8e8iscn4ncjuusoa7ddai@4ax.com... > On Tue, 4 Apr 2006 10:32:08 -0400, "Yuri Blanarovich" > wrote: > >>Now consider larger >>error from the wrong assumption or calculation caused by wrong current >>magnitudes and distribution. > > Hi Yuri, > > Why is it that you can say this so often, and yet never put a number > to it? > Experience, my dear, experience. If I am capabl;e of writing to you, I don't have to put number on it, how many letters of alphabet I master. > What is the error? You also speak of efficiency. What is the > efficiency? > Stick in the EZNEC and find out if you can't sleep without numbers. Anyone who looks at current distribution curves can see that there is a difference. No need for lawyers and precise numbers. If only this was the problem, then I would give you answer to 4 decimal places. You have greater problem with "gurus" not getting the big picture (or pretending to). > Very simple questions. Technically based. Selected because they seem > to be of supreme importance to you, and yet you don't seem to have a > handle on the situation. > I have the handle on it, appreciate the magnitude and with time there will be some numbers. Cecil posted files, anyone who is hang up on numbers can get them from the EZNEC if properly defined, instead of poking needles. We are having problem with people admitting there could be difference in the current across loading coils, and here the "problems" is what is the error? So lets stick to the big problem and fuggettabout detours and nitpicking. Yuri, K3BU > 73's > Richard Clark, KB7QHC Article: 223124 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Current across the antenna loading coil - from scratch References: <1143142526.021154.67050@e56g2000cwe.googlegroups.com> <1144062834.591149.121920@v46g2000cwv.googlegroups.com> <69aYf.63812$Jd.56966@newssvr25.news.prodigy.net> <1fWdnQLbJqyMyqzZnZ2dnUVZ_smdnZ2d@adelphia.com> <0veYf.11366$tN3.1035@newssvr27.news.prodigy.net> <8redneWq1um7A6zZRVn-iw@adelphia.com> <1235gvinaojtf1f@corp.supernews.com> <1144182367.544279.161490@e56g2000cwe.googlegroups.com> Message-ID: Date: Tue, 04 Apr 2006 20:50:41 GMT K7ITM wrote: > You really think so, Cecil?? I saw through it the first time you > posted it. As an EZNEC and NEC2 user, I know that not only the current > magnitude, but also its phase, is reported. I knew that what you > posted about it was incorrect. I don't see Roy's comment as agreeing > with you at all, but completely disagreeing. You said that it only > gave amplitude information, when in fact it gives phase and amplitude. Again, no quote from me. I have no idea to what you are responding or even if you are responding to something I said today or last year. I didn't say EZNEC doesn't give phase information. I said there is no phase information in the phase information that EXNEC gives. What is it about Gene's posting that you don't understand? > Regarding the cos(kz)*cos(wt) term in a standing wave: > > Gene Fuller, W4SZ wrote: >> In a standing wave antenna problem, such as the one you describe, there is no >> remaining phase information. Any specific phase characteristics of the traveling >> waves died out when the startup transients died out. >> >> Phase is gone. Kaput. Vanished. Cannot be recovered. Never to be seen again. >> >> The only "phase" remaining is the cos (kz) term, which is really an amplitude >> description, not a phase. -- 73, Cecil http://www.qsl.net/w5dxp Article: 223125 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Current across the antenna loading coil - from scratch References: <1143142526.021154.67050@e56g2000cwe.googlegroups.com> <0hf13258667d7d0m648bf6rbgm6ecrj2sl@4ax.com> <5qaYf.6$qO.0@fe10.lga> <1144131328.322721.32520@t31g2000cwb.googlegroups.com> <1k5532h8scbtg8e8iscn4ncjuusoa7ddai@4ax.com> Message-ID: Date: Tue, 04 Apr 2006 20:58:46 GMT Yuri Blanarovich wrote: > We are having problem with people admitting there could be difference in the > current across loading coils, and here the "problems" is what is the error? Actually, the problem is more elementary than coils. Everyone seems to understand coils installed in circuits. The ignorance seems to be of the nature of the physics involved in standing waves, whether on a wire or on a coil or in free space. So I have switched the discussion to where it belongs, to a discussion of standing waves, with or without coils, with or without wires. I offered the following example which the gurus refuse to touch with a ten foot pole. One wonders why. The transmission line is lossless and BB is a black box. Source-------a-BB-b-----------c-BB-d---------open circuit The current at 'a' is measured at one amp. The current at 'b' is measured at zero amps. The current at 'c' is measured at zero amps. The current at 'd' is measured at one amp. What's in the black boxes? Would you believe ZERO responses from the gurus? -- 73, Cecil http://www.qsl.net/w5dxp Article: 223126 of rec.radio.amateur.antenna From: "AK" Subject: Antenna RF choke questions Message-ID: <_7CYf.908089$xm3.833232@attbi_s21> Date: Tue, 04 Apr 2006 22:08:58 GMT Putting together a new Cushcraft A4S (10,15, 20m) beam. Cushcraft recommends using an 8-turn, 6-inch diameter RG8U coax cable coil as an RF choke for feeding the driven element. HyGain suggested the same thing for the TH2MK3 antenna I used many years ago -- only using 12 turns of RG8 (with the 6-inch outside diameter), rather than 8 turns. I have a few questions on the best way to do this. 1) Is it fair to assume that the more turns the better? 2) Should the coil be as close to the antenna feedpoint as possible, or is a foot or two of straight coax between the antenna input and the coil OK? 3) Would placing the coax coil around the mast (instead of taping one side of the coil to the mast as suggested) be a bad thing to do? 4) Is there a good website or book that describes the technical tradeoffs of a coax RF choke? ( I am sort of wondering if the choke can be skipped. Some time ago, I used a W2AU balun on a multiband dipole. All it did was create TVI when I went on 10 meters. Took the balun out, and the resonant points didn't change. I figured that if there were antenna currents on the coax, they would bring down the resonant frequency without the balun. Since that didn't happen, I figured the balun wasn't helping - - but balun core saturation at 30 MHz (with the KW on) was what was racking up the TVs.) 5) One last question - not having to do with the coax RF choke: Cushcraft "operating tips" say to not use vinyl tape on SO239 or PL-239 connectors. Why? What problem would the tape cause?? Thanks for any info - AK Article: 223127 of rec.radio.amateur.antenna From: Skipp is here Subject: Want a Maxcom Antenna Matcher (stop laughing please) Date: Tue, 4 Apr 2006 22:13:46 +0000 (UTC) Message-ID: Re: Want a Maxom Antenna Matcher I'm looking for one of the Maxcom Antenna Matcher Units. If you have one you'd like to part with for a fair price... please email me at the below email address, or take out the NOSPAMPLEASE from the reply header above. I know some of you are laughing because of what the Maxcom really is inside, but I'd like to buy a used one anyway. Thanks for reading this post cheers, skipp skipp025 at yahoo.com Article: 223128 of rec.radio.amateur.antenna From: ml Subject: elevator noise? Message-ID: Date: Tue, 04 Apr 2006 23:21:17 GMT today the elevator room on the roof is all relays, looks like a frankenstin set from the 50's wouldn't be surprized if the relays are actually from 50's either my antenna is mounted on the wall (brick) of this room currently i don't get any noise (electricial) Just found out the building is thinking of adding new elevators and modern controlers so now i wonder, should i suspect that they are all rf tight in metal housing's or a rf nightmare? anyone have any experience w/how much 'noise'/hash they might throw ooff? tnx m Article: 223129 of rec.radio.amateur.antenna From: ml Subject: Re: paint antenna? References: <122u6ah1aa5iv2e@corp.supernews.com> Message-ID: Date: Tue, 04 Apr 2006 23:23:58 GMT In article , Silfax wrote: > >> Dave WD9BDZ > > > > the bricks have been recently waterproffed, thou i guess they will still > > be soggy after a strong rain guess i'd just have to add a small amount > > of paint, and keep painting till swr etc are where it need to be to make > > resonant if it even works > > > > sounds like a fun experiment can't wait to snag some paint > > If you paint a yagi on the roof, how do you intend on rotating the building? my original post specified one direction , figured that's until i can rotate the building easily but if the antenna of this type worked well /was practical past the experiment stage wich was also specified as the point... then a better way would be to just paint 4 , one for each side and use a coax switch yeah thats cool Article: 223130 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Current across the antenna loading coil - from scratch References: <1143142526.021154.67050@e56g2000cwe.googlegroups.com> <1144062834.591149.121920@v46g2000cwv.googlegroups.com> <69aYf.63812$Jd.56966@newssvr25.news.prodigy.net> <1fWdnQLbJqyMyqzZnZ2dnUVZ_smdnZ2d@adelphia.com> <0veYf.11366$tN3.1035@newssvr27.news.prodigy.net> <8redneWq1um7A6zZRVn-iw@adelphia.com> <6Y-dnfdPp43xb6_ZRVn-tQ@adelphia.com> Message-ID: <%eDYf.44729$_S7.40838@newssvr14.news.prodigy.com> Date: Tue, 04 Apr 2006 23:24:43 GMT John Popelish wrote: > Cecil Moore wrote: >> So your equation is too simple to be useful. > > Thanks for agreeing with me. No - thank you for agreeing with me that your equation is too simple to be useful. :-) > That is not what the formula says. Pick and X and you get a constant > phase angle with respect to the zero degree reference. But that phase angle is not zero as it is for standing waves. You seem to be talking in circles. How can the phase shift between the traveling wave and the source reference ever be zero at a point 90 degrees away from the source? If it cannot, then you have evidence that the traveling wave is NOT identical to the standing wave as evidenced by their different equations. > Last time I looked, you were claiming > that one could use the self resonant frequency as a way to predict the > phase shift through a coil at other frequencies (to some rather open > tolerance) with the assumption of constant time delay. Where have you been? I gave up on that idea long ago. I even posted a Dr. Corum quote to that effect. You obviously need to look more often. Let's cut to the bottom line. You seem to believe that standing wave current is identical to traveling wave current. If that's your point, just say so. Otherwise, please tell us the difference between the standing wave current and the traveling wave current which seems obvious to me from the equations. -- 73, Cecil http://www.qsl.net/w5dxp Article: 223131 of rec.radio.amateur.antenna From: Roy Lewallen Subject: Re: Antenna RF choke questions Date: Tue, 04 Apr 2006 16:26:39 -0700 Message-ID: <123605h66a6vld1@corp.supernews.com> References: <_7CYf.908089$xm3.833232@attbi_s21> AK wrote: > Putting together a new Cushcraft A4S (10,15, 20m) beam. > > Cushcraft recommends using an 8-turn, 6-inch diameter RG8U coax cable coil > as an RF choke for feeding the driven element. HyGain suggested the same > thing for the TH2MK3 antenna I used many years ago -- only using 12 turns of > RG8 (with the 6-inch outside diameter), rather than 8 turns. I have a few > questions on the best way to do this. > > 1) Is it fair to assume that the more turns the better? No. The coil makes a broadly resonant circuit, which greatly increases its common mode impedance. Increasing the number of turns will lower it. > 2) Should the coil be as close to the antenna feedpoint as possible, or is a > foot or two of straight coax between the antenna input and the coil OK? No problem. > 3) Would placing the coax coil around the mast (instead of taping one side > of the coil to the mast as suggested) be a bad thing to do? Probably. It's likely to lower the resonant frequency, reducing the common mode impedance. > > 4) Is there a good website or book that describes the technical tradeoffs of > a coax RF choke? ( I am sort of wondering if the choke can be skipped. Some > time ago, I used a W2AU balun on a multiband dipole. All it did was create > TVI when I went on 10 meters. Took the balun out, and the resonant points > didn't change. I figured that if there were antenna currents on the coax, > they would bring down the resonant frequency without the balun. Since that > didn't happen, I figured the balun wasn't helping - - but balun core > saturation at 30 MHz (with the KW on) was what was racking up the TVs.) For general information on baluns and common mode chokes (called "current baluns" in the article), see http://eznec.com/Amateur/Articles/Baluns.pdf. For dimensions of air core chokes like yours, see the ARRL Handbook. That's an interesting story about the W2DU balun. There must have been a huge amount of common mode current, and insufficient balun impedance. > 5) One last question - not having to do with the coax RF choke: > Cushcraft "operating tips" say to not use vinyl tape on SO239 or PL-239 > connectors. Why? What problem would the tape cause?? Can't help you there. Roy Lewallen, W7EL Article: 223132 of rec.radio.amateur.antenna From: Roy Lewallen Subject: Re: Question about auto antenna cable and connectors Date: Tue, 04 Apr 2006 16:32:17 -0700 Message-ID: <12360g3fgj19iaf@corp.supernews.com> References: The coax used for every car radio of that vintage I ever saw (and I saw a lot) doesn't fit your description. It had a single, small diameter (#28 or so) wire rattling around loosely in a thin polyethylene tube, which was covered by a braided shield. The objective was to minimize the capacitance, but there obviously wasn't any control over Z0 or delay, since the small wire was free to move around inside the much larger diameter PE tube. There was no helically wound conductor. I think you might be looking in the wrong place for what you need. The connector fits your description, though. Roy Lewallen, W7EL Ronnie wrote: > Hi, > > This is not about ham radio, but rather a general question > about the type of cable and connectors that were found > between the antenna and the AM radio in GM cars in the > 60's. I'm trying to locate some technical information about > the cable and a source for the cable and connectors. > > I have an old airplane autopilot system that uses tuned circuit > to sense changes in the airplane's attitude and the position of > the control servos. Distributed variable inductances and > variable capacitors combine to establish the resonant > operating frequency of the system. The components are > connected together with specific lengths of cable and the > service manual points out that the lengths are critical because > of the added capacitance of the cable and connectors. > > The cable is marked as follows: > > "I. T. & T. Federal Cable R.E.C." > > It is a shielded cable with a spiral wound center conductor > that looks very much like the antenna cable I remember finding > in GM cars in the 60's. It also has the same type of connectors. > There is a center pin for the center conductor and a metal sleve > that extents back over the cable and makes a connection with the > shield and chassis of the radio. Friction holds the connector in > its mating socket - there are no threads, just a couple of splayed out > areas on the sleve. > > I was hoping one of you might be able to point me to a source > of technical information about this cable, such as the capacitance > per unit length, etc. The one piece I have measures about 10.5 pF / foot > or 415 pF / meter, but my measurements may not be all that accurate. > > Also, a source where the cable and connectors can be found today > would be appreciated. > > Thanks in advance for any help. > > Ronnie, N5CSE > > > Article: 223133 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Current across the antenna loading coil - from scratch References: <1143142526.021154.67050@e56g2000cwe.googlegroups.com> <1144062834.591149.121920@v46g2000cwv.googlegroups.com> <69aYf.63812$Jd.56966@newssvr25.news.prodigy.net> <1fWdnQLbJqyMyqzZnZ2dnUVZ_smdnZ2d@adelphia.com> <0veYf.11366$tN3.1035@newssvr27.news.prodigy.net> <8redneWq1um7A6zZRVn-iw@adelphia.com> <1235gvinaojtf1f@corp.supernews.com> <1235jnuqlvl9627@corp.supernews.com> Message-ID: Date: Wed, 05 Apr 2006 00:06:31 GMT Roy Lewallen wrote: > Since EZNEC has been mentioned so much lately, it's appropriate to point > out that it's able to calculate the current at all points along a > helically modeled loading inductor with what I believe to be very good > accuracy. And it does it without any use or knowledge of presumed > traveling voltage or current waves. Yet, EZNEC reports the difference in standing wave current and traveling wave current better than you do. EZNEC correctly reports the phase of the standing wave current to be essentially zero all up and down a 1/2WL dipole using small wire. EZNEC correctly reports the phase of the traveling wave current to be the number of degrees away from the source in a traveling wave antenna. EZNEC clearly recognizes the difference between standing wave current and traveling wave current. Yet you tried to use standing wave current with its unchanging phase to measure the phase shift through a coil. Standing wave current doesn't even change phase through 45 degrees of wire. Why would you expect it to change phase through 45 degrees of coil? -- 73, Cecil http://www.qsl.net/w5dxp Article: 223134 of rec.radio.amateur.antenna Message-ID: <443309E7.D3413253@earthlink.net> From: "Michael A. Terrell" Subject: Re: Question about auto antenna cable and connectors References: Date: Wed, 05 Apr 2006 00:07:36 GMT Ronnie wrote: > > Hi, > > This is not about ham radio, but rather a general question > about the type of cable and connectors that were found > between the antenna and the AM radio in GM cars in the > 60's. I'm trying to locate some technical information about > the cable and a source for the cable and connectors. > > I have an old airplane autopilot system that uses tuned circuit > to sense changes in the airplane's attitude and the position of > the control servos. Distributed variable inductances and > variable capacitors combine to establish the resonant > operating frequency of the system. The components are > connected together with specific lengths of cable and the > service manual points out that the lengths are critical because > of the added capacitance of the cable and connectors. > > The cable is marked as follows: > > "I. T. & T. Federal Cable R.E.C." > > It is a shielded cable with a spiral wound center conductor > that looks very much like the antenna cable I remember finding > in GM cars in the 60's. It also has the same type of connectors. > There is a center pin for the center conductor and a metal sleve > that extents back over the cable and makes a connection with the > shield and chassis of the radio. Friction holds the connector in > its mating socket - there are no threads, just a couple of splayed out > areas on the sleve. > > I was hoping one of you might be able to point me to a source > of technical information about this cable, such as the capacitance > per unit length, etc. The one piece I have measures about 10.5 pF / foot > or 415 pF / meter, but my measurements may not be all that accurate. > > Also, a source where the cable and connectors can be found today > would be appreciated. > > Thanks in advance for any help. > > Ronnie, N5CSE It was RG62 93 ohm coax. The connectors were called "Motorola" plugs. -- Service to my country? Been there, Done that, and I've got my DD214 to prove it. Member of DAV #85. Michael A. Terrell Central Florida Article: 223135 of rec.radio.amateur.antenna From: dplatt@radagast.org (Dave Platt) Subject: Re: Antenna RF choke questions Date: Wed, 05 Apr 2006 00:07:51 -0000 Message-ID: <12362inc65qk6f6@corp.supernews.com> References: <_7CYf.908089$xm3.833232@attbi_s21> <123605h66a6vld1@corp.supernews.com> >> 5) One last question - not having to do with the coax RF choke: >> Cushcraft "operating tips" say to not use vinyl tape on SO239 or PL-239 >> connectors. Why? What problem would the tape cause?? > >Can't help you there. My guess is that its biggest problem is that its presence will lead the user to the (false) conclusion that the connectors have actually been waterproofed by the application of the tape. Based on all I've seen and read, vinyl electrician's tape does a lousy job of waterproofing outdoor connections. Its adhesive doesn't make a good waterproof bond with the connector surface (especially the threaded part), and both the adhesive and the vinyl itself tend to become brittle after a few seasons of exposure to direct sunlight. It'll leak like a sieve, and water will wick into your SO-239/PL-259 connectors and infiltrate the coax. This tape does a decent job of protecting indoor electrical connections against accidental contact, but it's not good for waterproofing. I generally prefer a two-layer approach - an inner layer of something adherent to do the actual waterproofing, and an outer layer to protect against sunlight exposure and weathering and abrasion. For the inner layer, a self-fusing (self-amalgamating) rubber tape such as Daflex Stretch-N-Seal, Plymouth 122, or the like is a good choice. Some people prefer Coax Seal or various mastics, but some of these can be hell to remove from the connector and threads if you ever want to re-work it. For an outer layer, a brush-on "liquid electrical tape" can be used. Another possibility would be a black cotton "friction tape" - 3M suggests their type 1755 as an outer protection layer for connections insulated with rubber electrical tape. Even vinyl electrical tape can be used as an outer layer, I think - it doesn't have to be (or remain) waterproof, it just has to remain intact enough to protect the inner layer from direct sunlight. If you really want to be thorough, insulate and waterproof with self-amalgamating rubber tape, add a layer of frictape for physical protection, and then overpaint with "liquid electrical tape". -- Dave Platt AE6EO Hosting the Jade Warrior home page: http://www.radagast.org/jade-warrior I do _not_ wish to receive unsolicited commercial email, and I will boycott any company which has the gall to send me such ads! Article: 223136 of rec.radio.amateur.antenna From: - exray - Subject: Re: Question about auto antenna cable and connectors Date: Tue, 04 Apr 2006 20:27:45 -0400 Message-ID: <12363o61bhj7g5e@corp.supernews.com> References: <443309E7.D3413253@earthlink.net> Michael A. Terrell wrote: > > > It was RG62 93 ohm coax. Certainly not in older radios. I don't know what they sell nowadays. I've seen that 'spiral' type of cable. They basically used the spiral as a means of maintaining the centre conductor in the average 'middle' of the hollow dielectric. The combined inductance and capacitance of the old cable was somewhat critical but the older radios provided an antenna trimmer to compensate for the variations. The electrical model was essentially a "voltage probe" and doesn't necessarily follow common antenna/feedline rules and thought. -Bill Article: 223137 of rec.radio.amateur.antenna Date: Tue, 04 Apr 2006 20:38:25 -0500 From: Tom Ring Subject: Re: Current across the antenna loading coil - from scratch References: <1143142526.021154.67050@e56g2000cwe.googlegroups.com> <1144062834.591149.121920@v46g2000cwv.googlegroups.com> <69aYf.63812$Jd.56966@newssvr25.news.prodigy.net> <1fWdnQLbJqyMyqzZnZ2dnUVZ_smdnZ2d@adelphia.com> <0veYf.11366$tN3.1035@newssvr27.news.prodigy.net> <8redneWq1um7A6zZRVn-iw@adelphia.com> <1144111853.486784.119070@i39g2000cwa.googlegroups.com> <1233ji3112ktg52@corp.supernews.com> <1144121237.437722.6580@t31g2000cwb.googlegroups.com> <2UmYf.55240$F_3.33995@newssvr29.news.prodigy.net> <1144169267.442808.52620@t31g2000cwb.googlegroups.com> <1144174480.860727.84680@g10g2000cwb.googlegroups.com> <%SzYf.64388$Jd.53946@newssvr25.news.prodigy.net> Message-ID: <44331f91$0$7328$39cecf19@news.twtelecom.net> Cecil Moore wrote: > w8ji@akorn.net wrote: > >> Grow up Cecil. Everyone sees what you are doing. > > > Everyone should see that I am trying to discuss technical > issues while the rest of you object to the 5% of my postings > that are bad humor or complaints about how I am being > unfairly treated. > > Why do you refuse to discuss technical issues? For > instance, you have avoided responding to my black box > question. Are you afraid everyone will see just > how wrong you are? > No one likes a whiner Cecil. Especially when they appear to be pissing into the wind. tom K0TAR Article: 223138 of rec.radio.amateur.antenna From: Roy Lewallen Subject: Re: Current across the antenna loading coil - from scratch Date: Tue, 04 Apr 2006 18:38:01 -0700 Message-ID: <12367rr3qvcg642@corp.supernews.com> References: <1143142526.021154.67050@e56g2000cwe.googlegroups.com> <1144062834.591149.121920@v46g2000cwv.googlegroups.com> <69aYf.63812$Jd.56966@newssvr25.news.prodigy.net> <1fWdnQLbJqyMyqzZnZ2dnUVZ_smdnZ2d@adelphia.com> <0veYf.11366$tN3.1035@newssvr27.news.prodigy.net> <8redneWq1um7A6zZRVn-iw@adelphia.com> <1235gvinaojtf1f@corp.supernews.com> <1235jnuqlvl9627@corp.supernews.com> John Popelish wrote: > Cecil Moore wrote: > >> EZNEC clearly recognizes the difference between standing wave current >> and traveling wave current. Yet you tried to use standing wave current >> with its unchanging phase to measure the phase shift through a coil. >> Standing wave current doesn't even change phase through 45 degrees >> of wire. Why would you expect it to change phase through 45 degrees >> of coil? > > Not to be a stickler, but didn't you just chastise me for bringing up > coils, and you said you had no interest in discussing them, because that > subject was closed for you? > > Make up your mind, please. And in any case, the statement about EZNEC is incorrect. As I explained in a posting a short while ago, EZNEC has no awareness of nor does it make any use of traveling wave currents or voltages. It calculates only the total current from fundamental rules which don't involve traveling waves. Roy Lewallen, W7EL Article: 223139 of rec.radio.amateur.antenna Subject: Re: elevator noise? From: Doc Date: Tue, 04 Apr 2006 21:23:46 -0500 Message-ID: <1144203594_5151@sp6iad.superfeed.net> References: <3tv532dv6ssa32revk6mgee12o31v8tr89@4ax.com> In other words, you won't really know till the new system is actually installed. That means a 50/50 chance for or against. 'Doc Article: 223140 of rec.radio.amateur.antenna From: "AK" References: <_7CYf.908089$xm3.833232@attbi_s21> <123605h66a6vld1@corp.supernews.com> Subject: Re: Antenna RF choke questions Message-ID: Date: Wed, 05 Apr 2006 02:46:14 GMT Thanks for the reply, Roy. "Roy Lewallen" wrote in message news:123605h66a6vld1@corp.supernews.com... > AK wrote: >> Putting together a new Cushcraft A4S (10,15, 20m) beam. >> >> Cushcraft recommends using an 8-turn, 6-inch diameter RG8U coax cable >> coil as an RF choke for feeding the driven element. HyGain suggested the >> same thing for the TH2MK3 antenna I used many years ago -- only using 12 >> turns of RG8 (with the 6-inch outside diameter), rather than 8 turns. I >> have a few questions on the best way to do this. >> >> 1) Is it fair to assume that the more turns the better? > > No. The coil makes a broadly resonant circuit, which greatly increases its > common mode impedance. Increasing the number of turns will lower it. So it's not just working on inductance. I'm still wondering why Cushcaft recommends 8 turns and HyGain 12. >> 2) Should the coil be as close to the antenna feedpoint as possible, or >> is a foot or two of straight coax between the antenna input and the coil >> OK? > > No problem. > >> 3) Would placing the coax coil around the mast (instead of taping one >> side of the coil to the mast as suggested) be a bad thing to do? > > Probably. It's likely to lower the resonant frequency, reducing the common > mode impedance. OK >> >> 4) Is there a good website or book that describes the technical tradeoffs >> of a coax RF choke? ( I am sort of wondering if the choke can be skipped. >> Some time ago, I used a W2AU balun on a multiband dipole. All it did was >> create TVI when I went on 10 meters. Took the balun out, and the resonant >> points didn't change. I figured that if there were antenna currents on >> the coax, they would bring down the resonant frequency without the balun. >> Since that didn't happen, I figured the balun wasn't helping - - but >> balun core saturation at 30 MHz (with the KW on) was what was racking up >> the TVs.) > > For general information on baluns and common mode chokes (called "current > baluns" in the article), see http://eznec.com/Amateur/Articles/Baluns.pdf. > For dimensions of air core chokes like yours, see the ARRL Handbook. Very informative; still reading. > That's an interesting story about the W2DU balun. There must have been a > huge amount of common mode current, and insufficient balun impedance. Actually, it was a W2AU ( http://www.unadilla.com/w2awire.htm ) I used in the early 70's. >> 5) One last question - not having to do with the coax RF choke: >> Cushcraft "operating tips" say to not use vinyl tape on SO239 or PL-239 >> connectors. Why? What problem would the tape cause?? > > Can't help you there. Reg thinks it's the tape's lack of water sealing. I have been using some putty-like sealer on my 239s lately, but it is a mess to clean off when disconnecting and re-connecting the coax - as sometimes required. > > Roy Lewallen, W7EL 73, AK Article: 223141 of rec.radio.amateur.antenna From: "Ronnie" References: <443309E7.D3413253@earthlink.net> <12363o61bhj7g5e@corp.supernews.com> Subject: Re: Question about auto antenna cable and connectors Message-ID: <5eGYf.62116$H71.61164@newssvr13.news.prodigy.com> Date: Wed, 05 Apr 2006 02:48:33 GMT Thanks Bill. The autopilot service manual I have shows a hand drawn figure of the cable that indicates a curly or spiral twist to the center conductor which appears as you stated to help keep the center conductor in the middle of the tube. It also mentions that the characteristics and length of the cable is part of the tuned circuit, but doesn't give any data on the cable. Like you, I'm sure I've seen that type of cable somewhere in the past and thought it was in an automotive antenna application, but it could have been elsewhere. Ronnie "- exray -" wrote in message news:12363o61bhj7g5e@corp.supernews.com... > Michael A. Terrell wrote: > > >> >> >> It was RG62 93 ohm coax. > > Certainly not in older radios. I don't know what they sell nowadays. > > I've seen that 'spiral' type of cable. They basically used the spiral as > a means of maintaining the centre conductor in the average 'middle' of the > hollow dielectric. > > The combined inductance and capacitance of the old cable was somewhat > critical but the older radios provided an antenna trimmer to compensate > for the variations. The electrical model was essentially a "voltage > probe" and doesn't necessarily follow common antenna/feedline rules and > thought. > > -Bill Article: 223142 of rec.radio.amateur.antenna From: "Ronnie" References: <12360g3fgj19iaf@corp.supernews.com> Subject: Re: Question about auto antenna cable and connectors Message-ID: <5eGYf.62115$H71.16177@newssvr13.news.prodigy.com> Date: Wed, 05 Apr 2006 02:48:33 GMT Thanks Roy. Now that you mention it, I do remember the straight center conductor inside the much larger diameter PE tube. The autopilot service manual I have shows a hand drawn figure of the cable that indicates a curly or spiral twist to the center conductor which appears to help keep the center conductor in the middle of the tube. I also mentions that the characteristics and length of the cable is part of the tuned circuit, but doesn't give any data on the cable. The connectors are like the connectors that were on the auto radios back then. I wonder where those could be found today. I can't seem to find them in any of the distributor catalogs I have. Maybe a trip to an automobile junk yard. Ronnie "Roy Lewallen" wrote in message news:12360g3fgj19iaf@corp.supernews.com... > The coax used for every car radio of that vintage I ever saw (and I saw a > lot) doesn't fit your description. It had a single, small diameter (#28 or > so) wire rattling around loosely in a thin polyethylene tube, which was > covered by a braided shield. The objective was to minimize the > capacitance, but there obviously wasn't any control over Z0 or delay, > since the small wire was free to move around inside the much larger > diameter PE tube. There was no helically wound conductor. I think you > might be looking in the wrong place for what you need. The connector fits > your description, though. > > Roy Lewallen, W7EL > > Ronnie wrote: >> Hi, >> >> This is not about ham radio, but rather a general question >> about the type of cable and connectors that were found >> between the antenna and the AM radio in GM cars in the >> 60's. I'm trying to locate some technical information about >> the cable and a source for the cable and connectors. >> >> I have an old airplane autopilot system that uses tuned circuit >> to sense changes in the airplane's attitude and the position of >> the control servos. Distributed variable inductances and >> variable capacitors combine to establish the resonant >> operating frequency of the system. The components are >> connected together with specific lengths of cable and the >> service manual points out that the lengths are critical because >> of the added capacitance of the cable and connectors. >> >> The cable is marked as follows: >> >> "I. T. & T. Federal Cable R.E.C." >> >> It is a shielded cable with a spiral wound center conductor >> that looks very much like the antenna cable I remember finding >> in GM cars in the 60's. It also has the same type of connectors. >> There is a center pin for the center conductor and a metal sleve >> that extents back over the cable and makes a connection with the >> shield and chassis of the radio. Friction holds the connector in >> its mating socket - there are no threads, just a couple of splayed out >> areas on the sleve. >> >> I was hoping one of you might be able to point me to a source >> of technical information about this cable, such as the capacitance >> per unit length, etc. The one piece I have measures about 10.5 pF / foot >> or 415 pF / meter, but my measurements may not be all that accurate. >> >> Also, a source where the cable and connectors can be found today >> would be appreciated. >> >> Thanks in advance for any help. >> >> Ronnie, N5CSE >> >> Article: 223143 of rec.radio.amateur.antenna From: "AK" References: <_7CYf.908089$xm3.833232@attbi_s21> <123605h66a6vld1@corp.supernews.com> Subject: Re: Antenna RF choke questions Message-ID: Date: Wed, 05 Apr 2006 03:02:03 GMT "AK" wrote in message news:WbGYf.666481$084.607593@attbi_s22... > Thanks for the reply, Roy. > >>> 5) One last question - not having to do with the coax RF choke: >>> Cushcraft "operating tips" say to not use vinyl tape on SO239 or PL-239 >>> connectors. Why? What problem would the tape cause?? >> >> Can't help you there. > > Reg Please make that "Dave Platt" -- >thinks it's the tape's lack of water sealing. I have been using some >putty-like sealer on my 239s lately, but it is a mess to clean off when >disconnecting and re-connecting the coax - as sometimes required. >> >> Roy Lewallen, W7EL > > 73, AK Article: 223144 of rec.radio.amateur.antenna From: "AK" References: <_7CYf.908089$xm3.833232@attbi_s21> Subject: Re: Antenna RF choke questions Message-ID: Date: Wed, 05 Apr 2006 03:40:54 GMT "Reg Edwards" wrote in message news:f8-dnb2ureSnu67ZRVnygw@bt.com... > ========================================= > > A choke made of 8 turns, 6 inches diameter, has a resonant frequency > around 21 MHz and has an impedance greater than 1000 ohms in the 20 > meter and 10 meter bands. Thanks Reg. I'm wondering now what 12 turns would work out to?? > Chokes are best wound neatly in the form of a single layer solenoid. > Jumble wound choke coils can have funny effects. Mine is a single layer with lots of electrical tape keeping the turns close and pretty much all the same. > For design of chokes made with coax cable download program SELFRESS > from website below and run immediately. > ---- > ........................................................... > Regards from Reg, G4FGQ > For Free Radio Design Software go to > http://www.btinternet.com/~g4fgq.regp > ........................................................... Thanks again, and 73 - AK Article: 223145 of rec.radio.amateur.antenna From: "Yuri Blanarovich" References: <1143142526.021154.67050@e56g2000cwe.googlegroups.com> <0hf13258667d7d0m648bf6rbgm6ecrj2sl@4ax.com> <5qaYf.6$qO.0@fe10.lga> <1144131328.322721.32520@t31g2000cwb.googlegroups.com> <1k5532h8scbtg8e8iscn4ncjuusoa7ddai@4ax.com> <1144189479.684490.115390@z34g2000cwc.googlegroups.com> Subject: Re: Current across the antenna loading coil - from scratch Message-ID: Date: Wed, 5 Apr 2006 00:00:23 -0400 wrote in message news:1144189479.684490.115390@z34g2000cwc.googlegroups.com... > > Yuri Blanarovich wrote: >> We are having problem with people admitting there could be difference in >> the >> current across loading coils, and here the "problems" is what is the >> error? >> So lets stick to the big problem and fuggettabout detours and nitpicking. >> Yuri, K3BU > > Yuri, > Rather than playing like Cecil and making words for others, please post > the dates and statements made by people who say current cannot be > uneven at each end of a coil. > Now it's "cannot be uneven?" Your own words: To which W8JI replied: "The idea current is high in only the start of a coil is not correct. Model an antenna with EZnec, and look at the load. Model a coil in any software, and look at current. Read any textbook, even beginner's textbooks, and see what they say. Measure a real antenna yourself! ...... You are like to call names, insult people, and argue rather than take the time to learn basic electronics. This is in any book, including the ARRL Handbook. If you look at HOW an inductor works, the current flowing in one terminal ALWAYS equals the current flowing out the other terminal. and..... Measuring the current into and out of the loading coil with a small thermocouple RF meter, I detect no difference This is in close agreement with the model. " " > Show us where that is said with an exact in context quote, don't pull a > Cecil and invent something that you expect us to blindly accept as the > truth. > It would help if we knew what you were talking about. > 73 Tom > You still don't know what are we talking about? Cecil is playing? Can you answer questions that he posted and I posted? 73 Yuri Article: 223146 of rec.radio.amateur.antenna From: Roy Lewallen Subject: Re: Antenna RF choke questions Date: Tue, 04 Apr 2006 21:25:10 -0700 Message-ID: <1236hl8oko2m822@corp.supernews.com> References: <_7CYf.908089$xm3.833232@attbi_s21> <123605h66a6vld1@corp.supernews.com> AK wrote: > . . . >> That's an interesting story about the W2DU balun. There must have been a >> huge amount of common mode current, and insufficient balun impedance. > > Actually, it was a W2AU ( http://www.unadilla.com/w2awire.htm ) I used in > the early 70's. My mistake -- major difference. The W2AU balun was a voltage balun, so it had an extra winding connected between the two conductors. There's lots of opportunity there to produce huge fields in the ferrite. Roy Lewallen, W7EL Article: 223147 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Current across the antenna loading coil - from scratch References: <1143142526.021154.67050@e56g2000cwe.googlegroups.com> <1144062834.591149.121920@v46g2000cwv.googlegroups.com> <69aYf.63812$Jd.56966@newssvr25.news.prodigy.net> <1fWdnQLbJqyMyqzZnZ2dnUVZ_smdnZ2d@adelphia.com> <0veYf.11366$tN3.1035@newssvr27.news.prodigy.net> <8redneWq1um7A6zZRVn-iw@adelphia.com> <1235gvinaojtf1f@corp.supernews.com> <1235jnuqlvl9627@corp.supernews.com> <12367rr3qvcg642@corp.supernews.com> Message-ID: Date: Wed, 05 Apr 2006 04:30:49 GMT Roy Lewallen wrote: > And in any case, the statement about EZNEC is incorrect. As I explained > in a posting a short while ago, EZNEC has no awareness of nor does it > make any use of traveling wave currents or voltages. It calculates only > the total current from fundamental rules which don't involve traveling > waves. For anyone who thinks EZNEC doesn't report traveling wave currents differently from standing wave currents, please download the following files. http://www.qsl.net/w5dxp/testx.EZ This is a *traveling wave file*. EZNEC reports the nearly linear phase of the current from 0 degrees at the source to 90 degrees at the load. The file comes with a zero load in the center of that 90 degree run. EZNEC reports the current's phase at 45 degrees at that zero load. http://www.qsl.net/w5dxp/testy.EZ Removing the resistive load from testx.EZ turns it into a *standing wave configuration*. EZNEC reports the phase of the current close to zero degrees all up and down the wire. The file comes with a zero load in the center of the same wire as above. EZNEC reports the current's phase very near zero degrees. The phase is near zero degrees all up and down wire 2. Contrary to what you have been told, EZNEC clearly reports the difference between the traveling wave configuration and the standing wave configuration. The traveling wave current phase can be used to measure the phase shift through the wire (or through a coil). The standing wave current phase cannot. To summarize: For the traveling wave configuration, the current magnitude is essentially constant all up and down the line while the phase shifts smoothly from zero degrees at the source to 90 degrees at the resistive load. For the standing wave configuration, the current magnitude follows the familiar cosine envelope from source at zero degrees to the end of the antenna at 90 degrees. The phase of the standing wave current is unchanging near zero degrees all up and down the wire. -- 73, Cecil http://www.qsl.net/w5dxp Article: 223148 of rec.radio.amateur.antenna From: "west" Subject: Thin & Fat Yagis Message-ID: Date: Wed, 05 Apr 2006 05:35:23 GMT Take 2 Yagis or verticals built with aluminum tubing. Both are identical except the tubing in one is twice the diameter of the other. Besides size, what will the property differences be between the two? Will they load up the same? I don't mean to be flippant, but this question has been on my mind for a long time and I couldn't find the answer. All comments appreciated. Thank you. 73's, west AF4GC Article: 223149 of rec.radio.amateur.antenna From: "oli" Subject: DELTA LOOP Antenna calculator Date: Wed, 5 Apr 2006 10:39:14 +0200 Message-ID: <44338235$0$21261$8fcfb975@news.wanadoo.fr> Good morning gentlemen, I have put online few weeks ago, a DELTA LOOP antenna calculator on the antenna-street web site. This is easy to use html page, you just have to specify your work frequency and the number of elements that you want and the page calculate all dimensions. you can try it before to read the other part of this mail : http://www.antenna-street.com/delta-loop-1en.php (Note : other band will be available soon) Well, Now I would like to do better, and I would like to generate automatiquely a MMANA file from wich will be available directly by the soft to viw diagrams and most importants values (gain, swr, front/back dB etc.) Actualy, MMANA file is like a txt file with an .maa extension. then I think that it could be possible to generate a file from a php page. Maybe, some of you have already try to do it, then if you have any informations wich can help me to do it, it will be very appreciate. Best regards, Oli Article: 223150 of rec.radio.amateur.antenna From: ml Subject: Re: elevator noise?/sheilding tricks? References: <3tv532dv6ssa32revk6mgee12o31v8tr89@4ax.com> <1144203594_5151@sp6iad.superfeed.net> Message-ID: Date: Wed, 05 Apr 2006 09:54:31 GMT In article <1144203594_5151@sp6iad.superfeed.net>, Doc wrote: > In other words, you won't really know till the new system is > actually installed. That means a 50/50 chance for or against. > 'Doc thanks all, that responded guess i'll have to wait and see, i wouldn't mind doing a survey however i'd have no way to really know in the residential area i live which building have electroic elevator controllers or not , can't tell from outside and can't really poke around OK i guess a better question might have been: so if the controllers give off bad rf what is the best way to 'shield' those boxes so they won't bother my antennas outside the room? presume that i can ground the cabinents myself if they are not already . thanks Article: 223151 of rec.radio.amateur.antenna From: "Jeff" Subject: Re: Question about auto antenna cable and connectors Date: Wed, 5 Apr 2006 12:32:51 +0100 Message-ID: References: <12360g3fgj19iaf@corp.supernews.com> <5eGYf.62115$H71.16177@newssvr13.news.prodigy.com> Those connectors are still in use today in UK & Europe at least. A UK supplier is Maplin electronics. www.maplin.co.uk part no HHH12N Reagrds Jeff Article: 223152 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Current across the antenna loading coil - from scratch References: <1143142526.021154.67050@e56g2000cwe.googlegroups.com> <0hf13258667d7d0m648bf6rbgm6ecrj2sl@4ax.com> <5qaYf.6$qO.0@fe10.lga> <1144131328.322721.32520@t31g2000cwb.googlegroups.com> <1k5532h8scbtg8e8iscn4ncjuusoa7ddai@4ax.com> Message-ID: Date: Wed, 05 Apr 2006 11:57:14 GMT Ian White GM3SEK wrote: > In an Internet discussion, everybody has the right to attempt to switch > the discussion away from the point. Everybody seems to understand how a coil works. Very few people understand how standing waves work. There's no point in discussing what people already understand. There's every point in discussing what people don't understand. -- 73, Cecil http://www.qsl.net/w5dxp Article: 223153 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Current across the antenna loading coil - from scratch References: <1143142526.021154.67050@e56g2000cwe.googlegroups.com> <0hf13258667d7d0m648bf6rbgm6ecrj2sl@4ax.com> <5qaYf.6$qO.0@fe10.lga> <1144131328.322721.32520@t31g2000cwb.googlegroups.com> <1k5532h8scbtg8e8iscn4ncjuusoa7ddai@4ax.com> <1144189479.684490.115390@z34g2000cwc.googlegroups.com> <1144227516.569973.257170@u72g2000cwu.googlegroups.com> Message-ID: <0kOYf.64522$Jd.27816@newssvr25.news.prodigy.net> Date: Wed, 05 Apr 2006 12:01:00 GMT w8ji@akorn.net wrote: >>... the current flowing in one >>terminal ALWAYS equals the current flowing out the other terminal. > > That's true. That's essentially true for forward current and reflected current. Demonstrably not true for standing wave current. Even your own measurements showed that the current at one end of the coil is RARELY equal to the current at the other end of the coil. -- 73, Cecil http://www.qsl.net/w5dxp Article: 223154 of rec.radio.amateur.antenna From: "Yuri Blanarovich" References: Subject: Re: Thin & Fat Yagis Message-ID: Date: Wed, 5 Apr 2006 08:26:57 -0400 "west" wrote in message news:vGIYf.126985$g47.116874@tornado.tampabay.rr.com... > Take 2 Yagis or verticals built with aluminum tubing. Both are identical > except the tubing in one is twice the diameter of the other. Besides size, > what will the property differences be between the two? Will they load up > the same? I don't mean to be flippant, but this question has been on my > mind for a long time and I couldn't find the answer. All comments > appreciated. Thank you. > > 73's, west > AF4GC > > If the lenghth of the elements is the same and diameter is thicker, then the antenna with thicker elements will resonate lower on frequency. You need to shorten the elements on the fat one to bring it back to resonance. The fater elements provide broader bandwidth too and take more punishment. Yuri, K3BU Article: 223155 of rec.radio.amateur.antenna From: "Richard Fry" References: <0hf13258667d7d0m648bf6rbgm6ecrj2sl@4ax.com> <11783-4431A0B7-956@storefull-3254.bay.webtv.net> <44326790_1@newsfeed.slurp.net> <44329c0a_2@newsfeed.slurp.net> <4432a7f4_5@newsfeed.slurp.net> <2eb5329scje915brj9gmb9sd17ejvcvm9t@4ax.com> <4432d00b_4@newsfeed.slurp.net> Subject: Re: Current across the antenna loading coil - from scratch Date: Wed, 5 Apr 2006 07:33:10 -0500 Message-ID: <4433b845_3@newsfeed.slurp.net> > Richard Clark wrote: >> Any association between resonance, velocity of propagation, height, >> width, etc. and something like our 118.60° tall antenna needs a heap >> more explaining than resonance, velocity of propagation, height, width, >> etc. ______________ Now responding specifically to your request for a heap of explaining, you will find it in the George Brown paper I referenced earlier in this sub-thread. As that IRE paper from 1945 may be difficult to access now, you could refer to section 4-2 on the subject of cylindrical antennas in the "Antenna Engineering Handbook," 2nd edition (pub. 1984), by Johnson and Jasik -- from which this quote: "In practive the antenna is always fed by a transmission line. ... The effective terminal impedance of the line (often referred to as the antenna impedance) then depends not only on the length and diameter but also on the terminal condition." The text continues that for a MW monopole, the terminal condition consists of the characteristics of the ground plane. This section includes the plots of resistance and reactance for monopole radiators of various height to width ratios from George Brown's 1945 IRE paper. RF Article: 223156 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Current across the antenna loading coil - from scratch References: <1143142526.021154.67050@e56g2000cwe.googlegroups.com> <1144062834.591149.121920@v46g2000cwv.googlegroups.com> <69aYf.63812$Jd.56966@newssvr25.news.prodigy.net> <1fWdnQLbJqyMyqzZnZ2dnUVZ_smdnZ2d@adelphia.com> <0veYf.11366$tN3.1035@newssvr27.news.prodigy.net> <8redneWq1um7A6zZRVn-iw@adelphia.com> <1235gvinaojtf1f@corp.supernews.com> <1235jnuqlvl9627@corp.supernews.com> <12367rr3qvcg642@corp.supernews.com> Message-ID: Date: Wed, 05 Apr 2006 12:40:58 GMT Cecil Moore wrote: The testx.EZ file has been renamed to: http://www.qsl.net/w5dxp/TravWave.EZ The testy.EZ file has been renamed to: http://www.qsl.net/w5dxp/StndWave.EZ The current reported by EZNEC for TravWave.EZ contains the term cos(kz+wt) It's a traveling wave current, clearly not the same as a standing wave current. The current reported by EZNEC for StndWave.EZ contains the terms cos(kz)*cos(wt) It's a standing wave current, clearly not the same as a traveling wave current. Current reported by EZNEC every 10% of wire #2 is presented in the following table. The currents are obviously very different. The phase of the traveling wave progresses from 0 to 90 deg in 90 deg of wire. The phase of the standing wave doesn't progress beyond 0.11 of of degree. % along current in current in wire #2 TravWave.EZ StndWave.EZ 0% 0.9998 at -0.99 deg 0.9996 at 0 deg 10% 0.9983 at -9.39 deg 0.9843 at -0.03 deg 20% 0.9983 at -18.23 deg 0.9454 at -0.05 deg 30% 0.9957 at -27.59 deg 0.8843 at -0.06 deg 40% 0.9949 at -35.96 deg 0.8023 at -0.08 deg 50% 0.9945 at -44.84 deg 0.7014 at -0.09 deg 60% 0.9945 at -54.2 deg 0.584 at -0.09 deg 70% 0.9949 at -62.58 deg 0.4528 at -0.1 deg 80% 0.9956 at -71.43 deg 0.311 at -0.11 deg 90% 0.9965 at -80.27 deg 0.1616 at -0.11 deg 100% 0.9976 at -89.14 deg 0.006073 at -0.11 deg Some say "current is current". EZNEC disagrees. When reflected waves are eliminated, EZNEC indeed does accurately report traveling wave current. EZNEC reports the current that is there, whether it is traveling wave current or standing wave current. I'm trying to learn how to graph the above current magnitude and phase in Mathcad but not having much luck. -- 73, Cecil http://www.qsl.net/w5dxp Article: 223157 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Current across the antenna loading coil - from scratch References: <1144062834.591149.121920@v46g2000cwv.googlegroups.com> <69aYf.63812$Jd.56966@newssvr25.news.prodigy.net> <1fWdnQLbJqyMyqzZnZ2dnUVZ_smdnZ2d@adelphia.com> <0veYf.11366$tN3.1035@newssvr27.news.prodigy.net> <8redneWq1um7A6zZRVn-iw@adelphia.com> <1235gvinaojtf1f@corp.supernews.com> <1235jnuqlvl9627@corp.supernews.com> <12367rr3qvcg642@corp.supernews.com> Message-ID: Date: Wed, 05 Apr 2006 12:56:07 GMT Cecil Moore wrote: > % along current in current in > wire #2 TravWave.EZ StndWave.EZ > > 0% 0.9998 at -0.99 deg 0.9996 at 0 deg > 10% 0.9983 at -9.39 deg 0.9843 at -0.03 deg > 20% 0.9983 at -18.23 deg 0.9454 at -0.05 deg ^^^^^^ Sorry, a typo. Should be 0.9969 > 30% 0.9957 at -27.59 deg 0.8843 at -0.06 deg > 40% 0.9949 at -35.96 deg 0.8023 at -0.08 deg > 50% 0.9945 at -44.84 deg 0.7014 at -0.09 deg > 60% 0.9945 at -54.2 deg 0.584 at -0.09 deg > 70% 0.9949 at -62.58 deg 0.4528 at -0.1 deg > 80% 0.9956 at -71.43 deg 0.311 at -0.11 deg > 90% 0.9965 at -80.27 deg 0.1616 at -0.11 deg > 100% 0.9976 at -89.14 deg 0.006073 at -0.11 deg -- 73, Cecil http://www.qsl.net/w5dxp Article: 223158 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: New program. Input Z of a loaded line References: Message-ID: Date: Wed, 05 Apr 2006 13:25:41 GMT Reg Edwards wrote: > Also calculated are line attenuation, reflection coefficient, angle of > reflection coefficient, SWR, power efficiency, and the line loss in > decibels in the presence of SWR. Good stuff, Reg. Does it calculate the TLI reading? :-) -- 73, Cecil http://www.qsl.net/w5dxp Article: 223159 of rec.radio.amateur.antenna From: "Yuri Blanarovich" References: <1143142526.021154.67050@e56g2000cwe.googlegroups.com> <0hf13258667d7d0m648bf6rbgm6ecrj2sl@4ax.com> <5qaYf.6$qO.0@fe10.lga> <1144131328.322721.32520@t31g2000cwb.googlegroups.com> <1k5532h8scbtg8e8iscn4ncjuusoa7ddai@4ax.com> <1144189479.684490.115390@z34g2000cwc.googlegroups.com> <1144227516.569973.257170@u72g2000cwu.googlegroups.com> Subject: Re: Current across the antenna loading coil - from scratch Message-ID: <0BPYf.12$Dv.10@fe08.lga> Date: Wed, 5 Apr 2006 09:27:13 -0400 wrote in message news:1144227516.569973.257170@u72g2000cwu.googlegroups.com... > > Yuri Blanarovich wrote: >> Your own words: >> To which W8JI replied: >> >> "The idea current is high in only the start of a coil is not correct. >> Model an antenna with EZnec, and look at the load. Model a coil in any >> software, and look at current. Read any textbook, even beginner's >> textbooks, >> and see what they say. Measure a real antenna yourself! > > Where is the entire context of that comment Yuri? You (and Cecil) have > the habit of extracting things from context of a larger statement and > exaggerating or putting a creative spin on what others say. > > If you were saying the current is high only in the first few turns of a > coil that is not in a high order self-resonance, that is incorrect. > Now you are putting words in my mouth. The question and argument WAS and IS about the current being (almost) equal (you claimed), or DIFFERENT (my et other's claim) at the ENDS of the loading coil. You stated "ALWAYS EQUAL" (Kirchoff, bla, bla...). As illustration and description of the effect I observed on the Hustler resonator was, that the heat developed from the bottom few turns. Like I am so stupid to claim that there is high current only in your few turns? Common' give me a break and fes up!! This is getting comical and pathetic. . Anyone can look up the original posting about the development of the "story" at http://www.k3bu.us/loadingcoils.htm The whole dispute is summarized in Fig. 3 there, where it properly shows the shaded area representing reality - current and area at the whip after the loading coil vs. solid line representing misconception. (See degrees used there?) Anyone, even Richard can see that graphic representation of white area between the shaded area and triangular curve at the right, to see the the difference in efficiency ignored by the "same current" crowd - the white triangle is what you are missing! If you don't get it by now, then you have serious problem. Why don't you "gurus" repeat measurements, model it PROPERLY as solenoid or loading stub (or look at Cecil's examples) within the quarter wave resonant loaded antenna and tell me where and what IS WRONG on my web page. Step by step and arguments please. I am getting tired of this mental masturbation why it CAN'T BE when it IS. I tought that by now "same currentniks" would get it, but looks like too much resistance to admit being wrong. Well, looks like really need for comprehensive article to explain it, describe the experiments that anyone can replicate and set the record straight. If you choose not to believe it, that is your choice and you can live with it, who cares, really. Except that some people parade as experts, gurus, engineers, when they are not. They have odacity to attack others about misinformation, when they have same on their web pages. The even more sad thing is that apparently you influenced ON4UN to take the right information out of his latest edition of Low Band DXing book and replaced with your misinformation. It is all there in black and white, can't deny it, besides claiming being or having "JI Engineering" company, which you have no right to use that name or description, you ain't no engineer with degree. One last question Tom: How many electrical degrees has 60 ft tall tower (10" face) with circular (or hex, or whatever you choose) top hat of 20 ft diameter at 1.8 MHz? Can you answer Cecil's questions? Obviously NOT without admitting that you were and are wrong. No more "proofs" needed like potshots at Cecil's ex wife. I get better response from a brick wall when I hit it with hammer. I really have no more to say, the rest will be in the comprehensive article published for anyone to get the picture and decide for themseleves if this is important or valuable for them, or not. (I promise, I am peeved now :-) 73 Yuri Blanarovich, www.K3BU.us Rest is crap, twist and dance around the argument With couple more comments that I could not resist. :-) > If you were saying the current is high in only the first few turns your > statement was incorrect. > Any dummy would know that it would be DISTRIBUTED along the coil, not in few turns that you picked or shorted out! Argument was ACROSS the coil, or at IT's ends. SAME (you) vs. DIFFERENT (me)!!!!!!!!!!!!!!!!!!!!!!!!!!!!! Capish? > If you were saying it had something to do with a cosign shape, your > statement was not correct. > > Saying the current is NOT high in only the first few turns in a loading > coil in a working system is NOT the same as saying the current does not > vary or cannot vary. > >> You are like to call names, insult people, and argue rather than take the >> time to learn basic electronics. This is in any book, including the ARRL >> Handbook. If you look at HOW an inductor works, the current flowing in >> one >> terminal ALWAYS equals the current flowing out the other terminal. > > That's true. The only thing that causes any differential is when the > inductor has significant stray C to the outside world compared to the > "through" impedance. Current can't just vanish. > ITS THE STANDING WAVE CURRENT measurable with RF ammeters or current probes. How come it "vanishes" at the tip of quarter wave vertical, HUH???? Or you deny that too???? > I think that was explained at the same time. As I recall the > conversation, you were claiming current followed the same taper as the > antenna area it replaced and claiming only the first few turns had high > current. You claimed coil Q didn't matter because most of the current > was high only in a few turns. > CRAP! Make up some stories. > I was trying to point out that idea, that the Q does not matter and the > current is high only in the first few turns, is not correct by giving > examples where we cannot measure the change with thermal couple meters. > >> and..... >> >> Measuring the current into and out of the loading coil with a small >> thermocouple RF meter, I detect no difference This is in close agreement >> with the model. " " > > Measurements are at: > > http://www.w8ji.com/mobile_antenna_current_measurements_at_w8ji.htm > >> You still don't know what are we talking about? >> Cecil is playing? Can you answer questions that he posted and I posted? > > I've tried to answer every question Yuri, as have others. Does this > help clear up what I was trying to say? > WHERE? > As I recall you were claiming Q did not matter because current was high > only in the first few turns of a loading coil. > Yea, riiiiight, I am so stuuuupid! > I pointed out Q does not matter as people expect for a different > reason. The real reason Q does not have the large effect on FS is > ground losses in the system swamp out the effects of coil ESR. > > You said current difference was directly related to antenna area the > loading coil replaced, that the loading coil had to have the same > current slope as the area of antenna it replaced. If it replaced 80 > degrees of antenna, it had to have the same current differential as > that 80 degrees of antenna. Is that correct, or did I misunderstand > you? > > I was giving counter-points to that claim. > > For example I posted this: > > http://www.w8ji.com/agreeing_measurements.htm > > Do you disagee with anything I say or Roy said when it is in context of > the overall discussion?? > YOU and Roy disagree with REALITY!!!!!!!!!!!! > 73 Tom > Article: 223160 of rec.radio.amateur.antenna From: "GS" References: Subject: Re: elevator noise? Message-ID: Date: Wed, 5 Apr 2006 09:18:30 -0400 Having spent 10 years in the elevator industry, you'll find that new equipment is mostly solid state with relays only controlling the safety circuit and motor controls. The controller is encliosed in a steel cabinet and as a result is ussually well shielded. That being said, you did not indicate what type of drive system will be installed, SCR (DC motors), AC V3F Drive Etc or will the current drives be left as is. These could potentially be a source of noise depending on the manufacturer. Motor/Gen set (older DC drives) could be very noisy when the brushes are worn. Newer AC V3F drives could be noisy when DC injection is used for braking and holding the elevator at the floor (noise from the motor windings as they vibrate at who knows what frequency). Most mechanics will be willing to share the info when you see them, coffee helps. Remember the the elevator guys don't mind the sudden stops only the little jerks in between. Hi. Hi. 73's Guenther VE3CVS "ml" wrote in message news:m-66F49E.19211504042006@news.verizon.net... > today the elevator room on the roof is all relays, looks like a > frankenstin set from the 50's wouldn't be surprized if the relays are > actually from 50's either > > my antenna is mounted on the wall (brick) of this room > > currently i don't get any noise (electricial) > > > > Just found out the building is thinking of adding new elevators and > modern controlers > > so now i wonder, should i suspect that they are all rf tight in metal > housing's or a rf nightmare? > > > anyone have any experience w/how much 'noise'/hash they might throw ooff? > > tnx > > m Article: 223161 of rec.radio.amateur.antenna From: "John Passaneau" Subject: Re: elevator noise?/sheilding tricks? Date: Wed, 5 Apr 2006 09:39:44 -0400 Message-ID: References: <3tv532dv6ssa32revk6mgee12o31v8tr89@4ax.com> <1144203594_5151@sp6iad.superfeed.net> The new elevator that was installed in my building here at the university, puts out a large amount of noise on the AM broadcast band every time it moves. I believe they are doing some sort of phase control on the motor with little filtering. -- John Passaneau Penn State University Physics Dept. jxp16@psu.edu "ml" wrote in message news:m-33EE55.05543105042006@news.verizon.net... > In article <1144203594_5151@sp6iad.superfeed.net>, > Doc wrote: > >> In other words, you won't really know till the new system is >> actually installed. That means a 50/50 chance for or against. >> 'Doc > > thanks all, that responded > > guess i'll have to wait and see, > > i wouldn't mind doing a survey however i'd have no way to really know in > the residential area i live which building have electroic elevator > controllers or not , can't tell from outside and can't really poke > around > > > OK i guess a better question might have been: > > so if the controllers give off bad rf > > what is the best way to 'shield' those boxes so they won't bother my > antennas outside the room? > > presume that i can ground the cabinents myself if they are not already . > > > > thanks Article: 223162 of rec.radio.amateur.antenna From: "Ronnie" References: <12360g3fgj19iaf@corp.supernews.com> <5eGYf.62115$H71.16177@newssvr13.news.prodigy.com> Subject: Re: Question about auto antenna cable and connectors Message-ID: Date: Wed, 05 Apr 2006 13:40:34 GMT Thanks for the lead. I see them on their web site. Ronnie "Jeff" wrote in message news:e109sn$jr0$1@emma.aioe.org... > Those connectors are still in use today in UK & Europe at least. A UK > supplier is Maplin electronics. > > www.maplin.co.uk part no HHH12N > > Reagrds > Jeff > Article: 223163 of rec.radio.amateur.antenna From: Silfax Subject: Re: paint antenna? References: <122u6ah1aa5iv2e@corp.supernews.com> Message-ID: Date: Wed, 05 Apr 2006 14:05:47 GMT On 2006-04-04, ml wrote: >> If you paint a yagi on the roof, how do you intend on rotating the building? > > my original post specified one direction , figured that's until i can > rotate the building easily > > but if the antenna of this type worked well /was practical past the > experiment stage wich was also specified as the point... > > then a better way would be to just paint 4 , one for each side and use > a coax switch yeah thats cool I would try putting up a vertical stripe on the building and then paint the radials on the sidewalk/street. This could be the ultimate in stealth. Make the radials look like a crosswalk or the center line down the street. You could even paint the curb, to make a no parking zone radial. Article: 223164 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Current across the antenna loading coil - from scratch References: <1144062834.591149.121920@v46g2000cwv.googlegroups.com> <69aYf.63812$Jd.56966@newssvr25.news.prodigy.net> <1fWdnQLbJqyMyqzZnZ2dnUVZ_smdnZ2d@adelphia.com> <0veYf.11366$tN3.1035@newssvr27.news.prodigy.net> <8redneWq1um7A6zZRVn-iw@adelphia.com> <1235gvinaojtf1f@corp.supernews.com> <1144182367.544279.161490@e56g2000cwe.googlegroups.com> <1144247093.292828.276560@i40g2000cwc.googlegroups.com> Message-ID: Date: Wed, 05 Apr 2006 15:15:28 GMT K7ITM wrote: > Awww, MAN,Cecil. I am sorry. I had no idea that you were putting up > with a newsreader that can't follow threads, and in addition you have > such a severe short term memory loss that you can't follow what's been > posted within the past couple hours. My newsreader is indeed unthreaded. I remember what was posted but sometimes not by who. > We should be able to help you out with the newsreader problem if you > want. I prefer my newsreader unthreaded. I read postings in the order in which they are received by my newsserver. Nothing else is ever downloaded. If the context of a posting is not quoted, I never see it. > I've patched together below (from the newsreader I use, which does keep > track of all the branches of threads) what I wrote and what I was > replying to in this particular sub-thread, so you can see it all in one > place. I still don't see any technical content in those postings. I do apologize if I have offended you but I still don't understand how. But that is water under the bridge by now. Sorry, the discussion has progressed beyond coils. Take a look at my other posting about what EZNEC says about traveling wave current Vs standing wave current and you will be up to date. Then you can use your lumped-circuit theory to explain the major differences in those two kinds of currents reported by EZNEC. -- 73, Cecil http://www.qsl.net/w5dxp Article: 223165 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Current across the antenna loading coil - from scratch References: <1143142526.021154.67050@e56g2000cwe.googlegroups.com> <0hf13258667d7d0m648bf6rbgm6ecrj2sl@4ax.com> <5qaYf.6$qO.0@fe10.lga> <1144131328.322721.32520@t31g2000cwb.googlegroups.com> <1k5532h8scbtg8e8iscn4ncjuusoa7ddai@4ax.com> <1144248323.701847.71900@z34g2000cwc.googlegroups.com> Message-ID: Date: Wed, 05 Apr 2006 15:29:39 GMT K7ITM wrote: > From where I am, Cecil, it sounds a lot more like everyone is bored to > tears with standing waves, since they are nothing more than the result > of adding together a couple travelling waves, and everyone here > understood them LONG ago. Everyone *thought* they understood them. The assertion that "current is current" proves that they didn't really understand them. cos(kz + wt) is simply not the same thing as cos(kz)*cos(wt) There is no trig idenity that will make them the same. Even W7EL's assertion about EZNEC not worrying about traveling wave current is wrong. When reflected current is eliminated in the traveling wave antenna design, EZNEC faithfully reports the traveling wave current proportional to cos(kx+wt). Please comment on the tabular data that I posted from EZNEC. And again, I apologize for offending you. > As I've posted before, and as far as I know nobody's taken me up on it, > it's quite enlightening to see an animation of the standing > wave+travelling wave pattern that develops on a transmission line for > various values of the ratio between the two travelling wave amplitudes. > But once you've seen it, and likely even before, you know what you > need, and (most of us) can move on I've posted this java graphic before. The standing wave current is obviously not the same as the traveling current. http://users.pandora.be/educypedia/electronics/applets/ph14e/stwaverefl.htm -- 73, Cecil http://www.qsl.net/w5dxp Article: 223166 of rec.radio.amateur.antenna From: "David G. Nagel" Subject: Re: Question about auto antenna cable and connectors Date: Wed, 05 Apr 2006 10:36:05 -0500 Message-ID: <1237p0ba92lo86c@corp.supernews.com> References: <12360g3fgj19iaf@corp.supernews.com> <5eGYf.62115$H71.16177@newssvr13.news.prodigy.com> Ronnie wrote: > Thanks for the lead. I see them on their web site. > Ronnie > > "Jeff" wrote in message news:e109sn$jr0$1@emma.aioe.org... > >>Those connectors are still in use today in UK & Europe at least. A UK >>supplier is Maplin electronics. >> >>www.maplin.co.uk part no HHH12N >> >>Reagrds >>Jeff >> > > > Jeff and Ronnie; That type of connector is known as a "Motorola Connector". Developed by Motorola for their automobile radios. Dave N Article: 223167 of rec.radio.amateur.antenna From: chuck Subject: Re: Phase shift through... References: <1144250363.672328.321670@v46g2000cwv.googlegroups.com> Message-ID: <7URYf.332$sq5.0@newsread2.news.atl.earthlink.net> Date: Wed, 05 Apr 2006 16:04:19 GMT K7ITM wrote: > Just as we can make a short antenna resonant by adding a loading coil, > and the loading coil may be placed anywhere along the antenna if an > appropriate coil is chosen, we can make a long antenna resonant by > inserting a series capacitance along the antenna wire. > > When that physically long but electrically shortened to resonance > antenna is excited and a standing wave pattern develops, what is the > phase shift of the current through the loading capacitor? Is the > standing wave current on the two sides of the capacitor different, in a > manner similar to how it's different in a loading coil? > > If not, why not? > > Cheers, > Tom > Is it not true that any two conductors can be modeled as either a transmission line or a capacitor? At this level, there appears to be analytic symmetry with a series loading coil. Chuck Article: 223168 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Phase shift through... References: <1144250363.672328.321670@v46g2000cwv.googlegroups.com> Message-ID: <95SYf.55581$F_3.10204@newssvr29.news.prodigy.net> Date: Wed, 05 Apr 2006 16:18:13 GMT K7ITM wrote: > When that physically long but electrically shortened to resonance > antenna is excited and a standing wave pattern develops, what is the > phase shift of the current through the loading capacitor? Is the > standing wave current on the two sides of the capacitor different, in a > manner similar to how it's different in a loading coil? In order to answer the question, one has to understand the physics of standing waves. Most people don't understand the physics of standing waves. Understanding the physics of a capacitor embedded in a standing wave environment is pretty much moot if one doesn't understand the physics of standing waves. Please let's take first things first. -- 73, Cecil http://www.qsl.net/w5dxp Article: 223169 of rec.radio.amateur.antenna From: "Yuri Blanarovich" References: <0hf13258667d7d0m648bf6rbgm6ecrj2sl@4ax.com> <5qaYf.6$qO.0@fe10.lga> <1144131328.322721.32520@t31g2000cwb.googlegroups.com> <1k5532h8scbtg8e8iscn4ncjuusoa7ddai@4ax.com> <1144189479.684490.115390@z34g2000cwc.googlegroups.com> <1144227516.569973.257170@u72g2000cwu.googlegroups.com> <0BPYf.12$Dv.10@fe08.lga> <6po7321mo5mf347d3ebdjt86hbl7svk3oq@4ax.com> Subject: Re: Current across the antenna loading coil - from scratch Message-ID: Date: Wed, 5 Apr 2006 13:51:11 -0400 "Richard Clark" wrote > Hi Yuri, > > I can also see that any metrics are entirely missing as to ACTUAL > efficiency. You already admit you don't know and don't really care to > go there when you dismiss this discussion: But graphic representation gives rough idea to realize that it is not unimportant or worthy ignoring. If you wanna get precise metrics, stick the two versions of coil definition in the EZNEC, generate the curves and compare areas under the curve from the top of the coil to the tip. Then tell us that is negligible and was not worth of this exercise. I will get to it soon too. Yuri, K3BU Article: 223170 of rec.radio.amateur.antenna From: Jim Higgins Subject: Re: Antenna RF choke questions Message-ID: References: <_7CYf.908089$xm3.833232@attbi_s21> <123605h66a6vld1@corp.supernews.com> Date: Wed, 05 Apr 2006 17:58:02 GMT On Tue, 04 Apr 2006 20:05:34 -0700, Richard Clark wrote: >On Wed, 05 Apr 2006 02:46:14 GMT, "AK" wrote: > >>Reg thinks it's the tape's lack of water sealing. I have been using some >>putty-like sealer on my 239s lately, but it is a mess to clean off when >>disconnecting and re-connecting the coax - as sometimes required. > >Hi OM, > >Lay down a layer of tape first. >Seal it with the sealer (much cheaper from flower shops). >Lay down another layer of tape. For the past 20 years I've used the same piece of coax running to a ground mounted vertical antenna. The coax runs across the top of the ground. The threads of the PL259/SO239 connection at the antenna are sealed with plumber's grease on the threads of the connector. The barrel of the PL259 behind the threaded sleeve is wrapped with high quality white vinyl tape extending about 4 inches up the coax. I remove the PL259 every week or so in the summer to move the coax while I mow the lawn. About 6 months ago I figured it was time to inspect things so I cut off the PL259, expecting to find corrosion requiring cutting the coax back to find clean shield or requiring coax replacement. Not so. I found clean copper shield at the cut end. The coax jacket wasn't at all brittle so I soldered on a new PL259, greased it and the SO239, and figure I'm good to go for a few more years. Jim Higgins, KB3PU Article: 223171 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Mono Vertical to Multi-band References: <06ydnfof-O7smKnZnZ2dnUVZ_smdnZ2d@wideopenwest.com> Message-ID: Date: Wed, 05 Apr 2006 18:32:06 GMT Scott Gordon wrote: > I have a 40 ft vertical fed with coax that I am using today on 60 meters > with excellent results. I have 34 radials under it now at about 43 ft. > > I am wondering how I can use this antenna on other bands? 40, 20, 17, 15, > 12, and 10 meters. With a straight monopole, anything over 5/8 wavelength is not a good DX radiation pattern. So if you are into low angle radiation, the rule-of-thumb upper frequency limit for a 40 ft. monopole would be about 585/40' = 14.6 MHz. It would work well on 20m and deteriorate as the frequency increases above 14.6 Mhz. -- 73, Cecil http://www.qsl.net/w5dxp Article: 223172 of rec.radio.amateur.antenna From: "Steve Nosko" Subject: Re: Question about auto antenna cable and connectors Date: Wed, 5 Apr 2006 13:13:54 -0500 Message-ID: References: <443309E7.D3413253@earthlink.net> <12363o61bhj7g5e@corp.supernews.com> <5eGYf.62116$H71.61164@newssvr13.news.prodigy.com> Nope. That's where. Autos. A piece of spiral plastic "rod" around the solid wire center conductor to space it in the center of the over-sized-hole dielectric. I thought it was also a "Motorola" connector, but didn't want to sound arrogant (still working at the circle M Ranch, you know). The AM receiver antenna was (is) nothing more that a capacitive probe hooked to the input, so the smaller the loading cap the better. Gee, if I shill have some around, perhaps some experimentation to determine the Z0 ... OK ... project 9,735, on the list for retirement. (yea, right) 73, Steve, K9DCI I only saw it referred to as low capacitance cable. Don't know if the Z0 was specified "Ronnie" wrote in message news:5eGYf.62116$H71.61164@newssvr13.news.prodigy.com... > Thanks Bill. > > The autopilot service manual I have shows a hand > drawn figure of the cable that indicates a curly or spiral twist > to the center conductor which appears as you stated to help > keep the center conductor in the middle of the tube. It also > mentions that the characteristics and length of the cable is part > of the tuned circuit, but doesn't give any data on the cable. > > Like you, I'm sure I've seen that type of cable somewhere in > the past and thought it was in an automotive antenna application, > but it could have been elsewhere. > > Ronnie > > "- exray -" wrote in message > news:12363o61bhj7g5e@corp.supernews.com... > > Michael A. Terrell wrote: > > > > > >> > >> > >> It was RG62 93 ohm coax. > > > > Certainly not in older radios. I don't know what they sell nowadays. > > > > I've seen that 'spiral' type of cable. They basically used the spiral as > > a means of maintaining the centre conductor in the average 'middle' of the > > hollow dielectric. > > > > The combined inductance and capacitance of the old cable was somewhat > > critical but the older radios provided an antenna trimmer to compensate > > for the variations. The electrical model was essentially a "voltage > > probe" and doesn't necessarily follow common antenna/feedline rules and > > thought. > > > > -Bill > > Article: 223173 of rec.radio.amateur.antenna From: Michael Coslo Subject: Re: What is an EH antenna Date: Wed, 05 Apr 2006 15:20:47 -0400 Message-ID: References: <1143908604.326393.313760@j33g2000cwa.googlegroups.com> <2yUXf.18997$B_1.11490@edtnps89> <1230fue8b8chkbf@corp.supernews.com> <1144027979.662007.152180@g10g2000cwb.googlegroups.com> <1144107461.423187.109850@z34g2000cwc.googlegroups.com> w8ji@akorn.net wrote: > Michael Coslo wrote: >> Cecil Moore wrote: >>> w8ji@akorn.net wrote: >>>> No matter what facts multiple independent sources submit, those who >>>> have faith will ignore the facts. >>> :-) That apparently includes individuals with faith in the >>> lumped circuit model under conditions where it is known to >>> fail. :-) >> >> Aww Cecil, does every thread have to turn into that? 8^) > > > At least it isn't fractals, although it is getting almost that bad. Yeah, at least Cecil isn't threatening to sue anyone! ;^) - 73 de mike KB3EIA - Article: 223174 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: What is an EH antenna References: <1143908604.326393.313760@j33g2000cwa.googlegroups.com> <2yUXf.18997$B_1.11490@edtnps89> <1230fue8b8chkbf@corp.supernews.com> <1144027979.662007.152180@g10g2000cwb.googlegroups.com> <1144107461.423187.109850@z34g2000cwc.googlegroups.com> Message-ID: Date: Wed, 05 Apr 2006 19:23:35 GMT Michael Coslo wrote: > Yeah, at least Cecil isn't threatening to sue anyone! ;^) Sue asked me not to do that. :-) -- 73, Cecil http://www.qsl.net/w5dxp Article: 223175 of rec.radio.amateur.antenna From: Roy Lewallen Subject: Re: Question about auto antenna cable and connectors Date: Wed, 05 Apr 2006 12:45:46 -0700 Message-ID: <12387jdrj3qgsd8@corp.supernews.com> References: <443309E7.D3413253@earthlink.net> <12363o61bhj7g5e@corp.supernews.com> <44340C37.B9A3788D@earthlink.net> Michael A. Terrell wrote: > . . . > One of the engineers at Delco told me it was RG-62, and 93 ohms when > I was going to their annual car radio training back in the early '70s. > IBM also used RG-62 on their coaxial computer networking, but they used > BNC connectors. The automotive coax I'm familiar with isn't RG-62. Like automotive coax, RG-62 has a thin walled hollow insulating tube. But RG-62 has a polyethylene "string" which is helically wound around the center conductor to keep it centered in the hollow tube. The coax in every old automotive installation I've seen lacks this PE "string", so the center conductor is free to flop around inside the hollow tube. The effect of the "string" is to make RG-62's Z0 constant and predictable, and it will also increase the capacitance somewhat. Constant Z0 isn't important for the automotive application, and low capacitance is important. It seems to me the center conductor is smaller in the automotive coax than in RG-62, also. Roy Lewallen, W7EL Article: 223176 of rec.radio.amateur.antenna From: "Joel Kolstad" Subject: Re: RF/microwaves over Fiberoptic cable??? Date: Wed, 5 Apr 2006 12:56:35 -0700 Message-ID: <12388bgc2u8v438@corp.supernews.com> References: <3cc6g3-meh.ln1@p400bob.personal.cox.net> Richard, > Having done it often, I can say it is far, far simpler than that. It > is obtained through the evanescent mode and optical couplers just like > RF couplers work on the exactly the same principle. I'm told that this approach is relatively easy to detect in that it requires a fair amount of mechanical motion to achieve. Single-mode fiber is often used to detect minute changes in, e.g., bridges, and the idea is that -- while there may be other causes of significant mechanical motion to a fiber -- detecting it in the case of a secure line is cause for investigation. I've also been told, however, that you can use completely non-invasive (mechanically) techniques to sniff fiber... something involving the back-scatter of neutrons or somesuch. Don't know how much of that was science-fiction vs. readily doable with the funding of a major government, though. Article: 223177 of rec.radio.amateur.antenna From: "Richard Fry" References: <0hf13258667d7d0m648bf6rbgm6ecrj2sl@4ax.com> <11783-4431A0B7-956@storefull-3254.bay.webtv.net> <44326790_1@newsfeed.slurp.net> <44329c0a_2@newsfeed.slurp.net> <4432a7f4_5@newsfeed.slurp.net> <2eb5329scje915brj9gmb9sd17ejvcvm9t@4ax.com> <4432d00b_4@newsfeed.slurp.net> <4433b845_3@newsfeed.slurp.net> Subject: Re: Current across the antenna loading coil - from scratch Date: Wed, 5 Apr 2006 15:07:53 -0500 Message-ID: <443422d4_4@newsfeed.slurp.net> "Richard Clark" > 3. this does not explain how a 118.60° tall antenna comes to be > resonant through >>On Tue, 4 Apr 2006 12:11:20 -0500, "Richard Fry" wrote: >>>The effective electrical length of a MW monople radiator determines its >>>resonant frequencies, and that must include the velocity of propagation >>>along the structure -- which is a function of the height AND width of the >>>radiator (mainly), and the operating frequency. ______________ I have not stated that an unloaded broadcast monopole of any physical height should be made self-resonant, or even needs to be, for efficient radiation. Very few broadcast monopoles are. The ones that aren't are matched to resonance and the transmission line Zo by a network at the antenna feedpoint, as I also stated. What I wrote is that a radiator of "90 electrical degrees" when shown in the FCC database is NOT self-resonant, and referred to the experimental data >from George Brown, and the work of Johnson & Jasik to confirm what I wrote. Kraus, 3rd edition, Ch 14 has the mathematical analysis to support this, also. NEC shows this effect, as well. The rest of the examples in your post are based on your invalid assumption, for which my response is given above. RF Article: 223178 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Velocity Factors References: Message-ID: Date: Wed, 05 Apr 2006 20:25:20 GMT Reg Edwards wrote: > I daresay some of you have made measurements at one time or another. > The more data received the better. I can then take averages. I've only measured two of them, Reg. I measured "450" ohm ladder-line VF at approximately 0.9 and "300" ohm ladder- line at ~0.8. I was surprised since I assumed it would be opposite those results. -- 73, Cecil http://www.qsl.net/w5dxp Article: 223179 of rec.radio.amateur.antenna From: "Tom Donaly" Subject: Re: Phase shift through... References: <1144250363.672328.321670@v46g2000cwv.googlegroups.com> <95SYf.55581$F_3.10204@newssvr29.news.prodigy.net> Message-ID: <6KVYf.62316$H71.2986@newssvr13.news.prodigy.com> Date: Wed, 05 Apr 2006 20:26:42 GMT Cecil Moore wrote: > K7ITM wrote: > >> When that physically long but electrically shortened to resonance >> antenna is excited and a standing wave pattern develops, what is the >> phase shift of the current through the loading capacitor? Is the >> standing wave current on the two sides of the capacitor different, in a >> manner similar to how it's different in a loading coil? > > > In order to answer the question, one has to understand the > physics of standing waves. Most people don't understand the > physics of standing waves. Understanding the physics of a > capacitor embedded in a standing wave environment is pretty > much moot if one doesn't understand the physics of standing > waves. Please let's take first things first. You sure use a lot of words to signify the fact that you're sunk, Cecil, and don't have a clue. 73, Tom Donaly, KA6RUH Article: 223180 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Current across the antenna loading coil - from scratch References: <1143142526.021154.67050@e56g2000cwe.googlegroups.com> <0hf13258667d7d0m648bf6rbgm6ecrj2sl@4ax.com> <5qaYf.6$qO.0@fe10.lga> <1144131328.322721.32520@t31g2000cwb.googlegroups.com> <1k5532h8scbtg8e8iscn4ncjuusoa7ddai@4ax.com> Message-ID: Date: Wed, 05 Apr 2006 20:47:39 GMT Ian White GM3SEK wrote: > I am simply telling you straight. If you find the implications > disturbing beyond the import of my actual words, that is beyond my control. You are trying to tell me what I think when you have no clue as to what I am thinking. Excuse my French, but that is called mind-fucking, Ian. Please cease and desist from that practice. The only ethical and honest thing you can say about my postings is, "it seems to me that you are saying or thinking such and such ..." > Our basic disagreements are about coils *and* current *and* their > behaviour when standing waves are present. There's no point in switching > the discussion to cover only part of those topics. Not switching the discussion to the only salient point of disagreement will obfuscate the discussion. If that's what you want to do, then your reasons for doing so are quite obvious, and readers are likely to assume that you are not interested in technical facts at all but more interested in preserving your omniscient guru status through obfuscation. So the real question is: Why have you avoided responding to my tabular current posting based on EZNEC's take on traveling wave current Vs standing wave current? Some may assume from that lack of response that you are afraid to address the technical facts as are W8JI and W7EL. If you guys are so right, why are you afraid of discussint the technical issues that I have posted? -- 73, Cecil http://www.qsl.net/w5dxp Article: 223181 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Phase shift through... References: <1144250363.672328.321670@v46g2000cwv.googlegroups.com> <95SYf.55581$F_3.10204@newssvr29.news.prodigy.net> <6KVYf.62316$H71.2986@newssvr13.news.prodigy.com> Message-ID: <07WYf.62329$H71.7497@newssvr13.news.prodigy.com> Date: Wed, 05 Apr 2006 20:53:16 GMT Tom Donaly wrote: > You sure use a lot of words to signify the fact that you're > sunk, Cecil, and don't have a clue. The technical content of your posting is duely noted, Tom, for all the world to observe. Do you really believe that such an ad hominem gut feeling statement has any impact or technical value at all? (Rhetorical question) It reminds me of what an eight year old would say. If you really want to make a technical impact, please respond to my tabular data table concerning EZNEC traveling wave current values Vs standing wave current values. -- 73, Cecil http://www.qsl.net/w5dxp Article: 223182 of rec.radio.amateur.antenna From: "Ronnie" References: <443309E7.D3413253@earthlink.net> <12363o61bhj7g5e@corp.supernews.com> <44340C37.B9A3788D@earthlink.net> <12387jdrj3qgsd8@corp.supernews.com> Subject: Re: Question about auto antenna cable and connectors Message-ID: Date: Wed, 05 Apr 2006 20:57:14 GMT Roy is right. I looked up RG62 and this is not the cable I have. Here's what the autopilot service manual has to say about this cable. "The coaxial harness assembly CD-1, 2 and 3 is manufacued to specific lenghts and since the cable is a part of the tuned circuit, these lengths must not be altered. The sensor leads are made of very fine wires that are fed through a hollow insulator. Note that the fine wire has been coiled to provide flexibility and reduce the possibility of beaking and causing an open in the circuit." The diagram shows a hollow tube with a fine wire that is coiled running through it, a braid style shield over the hollow tube and an outer jacket over the braid. It seems to be a variant of the auto coax where the fine wire center conductor has been coiled instead of being left straight. Thanks for all the help with this, but don't worry yourselves about it. I have all the orginal pieces with connectors intact, but I was hoping to find the technical specs on the cable so I could understand the cable's impact on the resonant frequency. Ronnie "Roy Lewallen" wrote in message news:12387jdrj3qgsd8@corp.supernews.com... > Michael A. Terrell wrote: >> . . . >> One of the engineers at Delco told me it was RG-62, and 93 ohms when >> I was going to their annual car radio training back in the early '70s. >> IBM also used RG-62 on their coaxial computer networking, but they used >> BNC connectors. > > The automotive coax I'm familiar with isn't RG-62. > > Like automotive coax, RG-62 has a thin walled hollow insulating tube. But > RG-62 has a polyethylene "string" which is helically wound around the > center conductor to keep it centered in the hollow tube. The coax in every > old automotive installation I've seen lacks this PE "string", so the > center conductor is free to flop around inside the hollow tube. The effect > of the "string" is to make RG-62's Z0 constant and predictable, and it > will also increase the capacitance somewhat. Constant Z0 isn't important > for the automotive application, and low capacitance is important. > > It seems to me the center conductor is smaller in the automotive coax than > in RG-62, also. > > Roy Lewallen, W7EL Article: 223183 of rec.radio.amateur.antenna From: Owen Duffy Subject: Re: Velocity Factors Message-ID: References: Date: Wed, 05 Apr 2006 23:11:56 GMT On Wed, 5 Apr 2006 21:09:10 +0100, "Reg Edwards" wrote: >I should like to know the velocity factors which occur on various >twin-balanced transmission lines. We have - Some of these are included in my line loss calculator at http://www.vk1od.net/tl/tllce.php and are displayed along with calculated results. See below... > >Open wire lines with infrequently spaced, flimsey spacers. > >450-ohm ladder lines of various sorts. Wes' measurements of Wireman lines are shown as Wireman 551 .. 554. > >300-ohm lines spaced with a thin continuous web. I have measured TV ribbon of this type with a 7.5mm conductor spacing and IIRC was around 82%. Similar line with puched out peices was around 87% from memory. I you need, I can measure the punched type, I am not sure if I have the plain ribbon around. > >130-ohm lines with two insulated wires stuck close together like twin >speaker cable. See ZIP 105 for K8ZOA's measurements of US Zip cord. See Australian twin flex for my measurements of Oz figure 8 flex. > >75-ohm lines embedded in a solid eliptical-shaped polythene. See Belden 8210 and 8222 (from Belden specs). > >I daresay some of you have made measurements at one time or another. >The more data received the better. I can then take averages. I can see someone wanting to by 10m of "average cable"... but I think I know what you mean! Hope this helps. Owen -- Article: 223184 of rec.radio.amateur.antenna From: "Ken Bessler" Subject: Unknown coax id help? Message-ID: <6wYYf.4689$fS6.618@dukeread11> Date: Wed, 5 Apr 2006 18:36:26 -0500 The label on this coax reads: "CFD200-NL LOW LOSS 50 OHM COAXIAL CABLE COMMATE/PEWC 3D" All I could find was a spec saying it has a VF of .83 and I measured the OD (0.195"). The cable is very stiff for it's size - like 9913 almost. Anyone care to guess? I'd love to take it apart (it's a RP-TNC - N Male 5' pigtail) but it's such a nice job I don't want to. Maybe it's a copy of LMR-200? I'll be using it to connect my 802.11b/g equipment (100mW, 2412mhz) to the main feedline (30' flexi 4xl with clamp type N connectors feeding a 16 el collinear antenna at 25' agl). Help? -- 73's de Ken KG0WX - Kadiddlehopper #11808, Flying Pigs #-1055, Grid EM17io, Elecraft K2 #4913, XG2, 4SQRP Tenna Dipper, Heath GD-1B, MP-1(X)antenna Article: 223185 of rec.radio.amateur.antenna From: "Tom Donaly" Subject: Re: Phase shift through... References: <1144250363.672328.321670@v46g2000cwv.googlegroups.com> <95SYf.55581$F_3.10204@newssvr29.news.prodigy.net> <6KVYf.62316$H71.2986@newssvr13.news.prodigy.com> <07WYf.62329$H71.7497@newssvr13.news.prodigy.com> Message-ID: Date: Wed, 05 Apr 2006 23:56:19 GMT Cecil Moore wrote: > Tom Donaly wrote: > >> You sure use a lot of words to signify the fact that you're >> sunk, Cecil, and don't have a clue. > > > The technical content of your posting is duely noted, Tom, > for all the world to observe. Do you really believe that > such an ad hominem gut feeling statement has any impact or > technical value at all? (Rhetorical question) > > It reminds me of what an eight year old would say. > > If you really want to make a technical impact, please > respond to my tabular data table concerning EZNEC traveling > wave current values Vs standing wave current values. Cecil, you've proven over and over again that you're not interested in technical discussion. You are interested in argument and a crude sort of digladiation where you do the verbal equivalent of kicking, biting, hitting below the belt, rabbit and sucker punching, throwing sand, popping steroids and amphetamines,and shooting people in the back. All this is being duly noted by the participants who by now have consigned your theories to the fractal junk pile. Come back when you're really interested in a technical discussion. The kind of discourse you enjoy is only fit for ending marriages. 73, Tom Donaly, KA6RUH Article: 223186 of rec.radio.amateur.antenna Subject: Re: Unknown coax id help? From: Ed References: <6wYYf.4689$fS6.618@dukeread11> Message-ID: Date: 06 Apr 2006 00:16:06 GMT > The label on this coax reads: > > "CFD200-NL LOW LOSS 50 OHM COAXIAL CABLE COMMATE/PEWC 3D" > > All I could find was a spec saying it has a VF of .83 and I measured > the OD (0.195"). The cable is very stiff for it's size - like 9913 > almost. > > Anyone care to guess? I'd love to take it apart (it's a RP-TNC - N > Male 5' pigtail) but it's such a nice job I don't want to. Maybe it's > a copy of LMR-200? I guess my Google skills are better than yours! :^) Try: http://www.commate.com.tw/ Click on "Low Loss Cables, then click on "CFD200" Looks pretty Lossy, to me, if you are going to use it at 2.6GHz. Ed K7AAT Article: 223187 of rec.radio.amateur.antenna From: "Ken Bessler" References: <6wYYf.4689$fS6.618@dukeread11> Subject: Re: Unknown coax id help? Message-ID: Date: Wed, 5 Apr 2006 19:24:54 -0500 "Ed" wrote in message news:Xns979CB0084585Cspectrumhogstarbandn@198.186.192.196... > > > The label on this coax reads: > > > > "CFD200-NL LOW LOSS 50 OHM COAXIAL CABLE COMMATE/PEWC 3D" > > > > All I could find was a spec saying it has a VF of .83 and I measured > > the OD (0.195"). The cable is very stiff for it's size - like 9913 > > almost. > > > > Anyone care to guess? I'd love to take it apart (it's a RP-TNC - N > > Male 5' pigtail) but it's such a nice job I don't want to. Maybe it's > > a copy of LMR-200? > > > > I guess my Google skills are better than yours! :^) > > Try: http://www.commate.com.tw/ > > Click on "Low Loss Cables, > > then click on "CFD200" > > Looks pretty Lossy, to me, if you are going to use it at 2.6GHz. > > > Ed K7AAT Actually, I did google and yahoo and I saw the reference to the tw website but I passed, fearing language problems. Guess I should have given it a look see. Lossy? My math says 0.845 db loss for my 5' pigtail - from what I've read recently that's not to bad for a rg-58 size pigtail, esp. on 2.4 gigs... Maybe I'm wrong? Feel free to teach me. :-) Thanks for the link. Ken KG0WX Article: 223188 of rec.radio.amateur.antenna From: "Richard Fry" References: <0hf13258667d7d0m648bf6rbgm6ecrj2sl@4ax.com> <11783-4431A0B7-956@storefull-3254.bay.webtv.net> <44326790_1@newsfeed.slurp.net> <44329c0a_2@newsfeed.slurp.net> <4432a7f4_5@newsfeed.slurp.net> <2eb5329scje915brj9gmb9sd17ejvcvm9t@4ax.com> <4432d00b_4@newsfeed.slurp.net> <4433b845_3@newsfeed.slurp.net> <443422d4_4@newsfeed.slurp.net> <2gl83250938id6bp54hodrkenm2mffnoje@4ax.com> Subject: Re: Current across the antenna loading coil - from scratch Date: Wed, 5 Apr 2006 19:51:45 -0500 Message-ID: <4434655c_5@newsfeed.slurp.net> "Richard Clark"wrote > Sounds like you have a problem following context. ___________ No, from your posts IMO it is YOU who has a problem with your reading comprehension, and/or possibly your professional integrity. I posted "The effective electrical length of a MW monopole radiator determines its resonant frequencies, and that must include the velocity of propagation along the structure -- which is a function of the height AND width of the radiator (mainly), and the operating frequency." I have also posted several references in the literature which support this in technical detail. You then posted "3. this does not explain how a 118.60° tall antenna comes to be resonant ," and several ridiculous examples of broadcast tower widths of 364 feet and more that you falsely attribute as flowing from my statements. Contrary to your recent post, I have never written anything that remotely implied that your 118.60 degree radiator, or a broadcast radiator of any other length can/should be made self-resonant by the use of an impractical ratio of width to length. I have posted several times that (conventional) broadcast radiators that are not self-resonant are brought to resonance at the feedpoint by the use of a matching network there. If you can find ANYTHING in my posts on this subject to support your statements, please quote them to the NG. Otherwise I suggest you let this thread close, and (hopefully), learn from it. RF Article: 223189 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Current across the antenna loading coil - from scratch References: <1143142526.021154.67050@e56g2000cwe.googlegroups.com> <0hf13258667d7d0m648bf6rbgm6ecrj2sl@4ax.com> <5qaYf.6$qO.0@fe10.lga> <1144131328.322721.32520@t31g2000cwb.googlegroups.com> <1k5532h8scbtg8e8iscn4ncjuusoa7ddai@4ax.com> Message-ID: Date: Thu, 06 Apr 2006 01:22:57 GMT Ian White GM3SEK wrote: > Based entirely on what you yourself have written, I have told you that > you don't understand something. Are the odds zero that it might be your misunderstanding? Please respond to this previous posting: The testx.EZ file has been renamed to: http://www.qsl.net/w5dxp/TravWave.EZ The testy.EZ file has been renamed to: http://www.qsl.net/w5dxp/StndWave.EZ The current reported by EZNEC for TravWave.EZ contains the term cos(kz+wt) It's a traveling wave current, clearly not the same as a standing wave current. The current reported by EZNEC for StndWave.EZ contains the terms cos(kz)*cos(wt) It's a standing wave current, clearly not the same as a traveling wave current. Current reported by EZNEC every 10% of wire #2 is presented in the following table. The currents are obviously very different. The phase of the traveling wave progresses from 0 to 90 deg in 90 deg of wire. The phase of the standing wave doesn't progress beyond 0.11 of of degree. % along current in current in wire #2 TravWave.EZ StndWave.EZ 0% 0.9998 at -0.99 deg 0.9996 at 0 deg 10% 0.9983 at -9.39 deg 0.9843 at -0.03 deg 20% 0.9969 at -18.23 deg 0.9454 at -0.05 deg 30% 0.9957 at -27.59 deg 0.8843 at -0.06 deg 40% 0.9949 at -35.96 deg 0.8023 at -0.08 deg 50% 0.9945 at -44.84 deg 0.7014 at -0.09 deg 60% 0.9945 at -54.20 deg 0.5840 at -0.09 deg 70% 0.9949 at -62.58 deg 0.4528 at -0.10 deg 80% 0.9956 at -71.43 deg 0.3110 at -0.11 deg 90% 0.9965 at -80.27 deg 0.1616 at -0.11 deg 100% 0.9976 at -89.14 deg 0.0061 at -0.11 deg Some say "current is current". EZNEC disagrees. When reflected waves are eliminated, EZNEC indeed does accurately report traveling wave current. EZNEC reports the current that is there, whether it is traveling wave current or standing wave current. -- 73, Cecil http://www.qsl.net/w5dxp Article: 223190 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Phase shift through... References: <1144250363.672328.321670@v46g2000cwv.googlegroups.com> <95SYf.55581$F_3.10204@newssvr29.news.prodigy.net> <6KVYf.62316$H71.2986@newssvr13.news.prodigy.com> <07WYf.62329$H71.7497@newssvr13.news.prodigy.com> Message-ID: Date: Thu, 06 Apr 2006 01:26:04 GMT Tom Donaly wrote: > Cecil, you've proven over and over again that you're not > interested in technical discussion. Allow me to disprove your opinion of me. Please respond to this earlier posting of mine: The testx.EZ file has been renamed to: http://www.qsl.net/w5dxp/TravWave.EZ The testy.EZ file has been renamed to: http://www.qsl.net/w5dxp/StndWave.EZ The current reported by EZNEC for TravWave.EZ contains the term cos(kz+wt) It's a traveling wave current, clearly not the same as a standing wave current. The current reported by EZNEC for StndWave.EZ contains the terms cos(kz)*cos(wt) It's a standing wave current, clearly not the same as a traveling wave current. Current reported by EZNEC every 10% of wire #2 is presented in the following table. The currents are obviously very different. The phase of the traveling wave progresses from 0 to 90 deg in 90 deg of wire. The phase of the standing wave doesn't progress beyond 0.11 of of degree. % along current in current in wire #2 TravWave.EZ StndWave.EZ 0% 0.9998 at -0.99 deg 0.9996 at 0 deg 10% 0.9983 at -9.39 deg 0.9843 at -0.03 deg 20% 0.9969 at -18.23 deg 0.9454 at -0.05 deg 30% 0.9957 at -27.59 deg 0.8843 at -0.06 deg 40% 0.9949 at -35.96 deg 0.8023 at -0.08 deg 50% 0.9945 at -44.84 deg 0.7014 at -0.09 deg 60% 0.9945 at -54.20 deg 0.5840 at -0.09 deg 70% 0.9949 at -62.58 deg 0.4528 at -0.10 deg 80% 0.9956 at -71.43 deg 0.3110 at -0.11 deg 90% 0.9965 at -80.27 deg 0.1616 at -0.11 deg 100% 0.9976 at -89.14 deg 0.0061 at -0.11 deg Some say "current is current". EZNEC disagrees. When reflected waves are eliminated, EZNEC indeed does accurately report traveling wave current. EZNEC reports the current that is there, whether it is traveling wave current or standing wave current. -- 73, Cecil http://www.qsl.net/w5dxp Article: 223191 of rec.radio.amateur.antenna From: "Steven Polczynski" References: Subject: Re: building a yagi Message-ID: <4m_Yf.62380$H71.12519@newssvr13.news.prodigy.com> Date: Thu, 06 Apr 2006 01:42:24 GMT You can get aluminum tubing from an aircraft supplier. it comes in 12' lengths. it would be a pretty expensive antenna but would last a long time. "Leadfoot" wrote in message news:hu3Uf.7382$lb.659961@news1.epix.net... >I going to build a 11 element yagi but the problem I'm having is I can't >find the aluminum rods, I was wondering if I use copper if I will still get >the same Db gain. > > I was thinking of another metal was to use brake line from a car that I > can get in the auto parts store. > > Thanks > Ledfoot > > Article: 223192 of rec.radio.amateur.antenna Subject: Re: Unknown coax id help? From: Ed References: <6wYYf.4689$fS6.618@dukeread11> Message-ID: Date: 06 Apr 2006 02:15:07 GMT > Actually, I did google and yahoo and I saw the reference to the tw > website but I passed, fearing language problems. Guess I should > have given it a look see. > > Lossy? My math says 0.845 db loss for my 5' pigtail - from what > I've read recently that's not to bad for a rg-58 size pigtail, esp. on > 2.4 gigs... > > Maybe I'm wrong? Feel free to teach me. :-) No, Ken, you're not wrong. I forgot you were only using a 5' pigtail.... although you could probably get lower loss stuff. I don't know what your application is, but you're right.... probably doesn't matter that much. Ed Article: 223193 of rec.radio.amateur.antenna From: "amdx" Subject: Transforner Theory Date: Wed, 5 Apr 2006 21:22:04 -0500 Message-ID: <74ac6$44347c7f$45011502$11431@KNOLOGY.NET> Hi All, Info below from the following site---- http://www.ee.surrey.ac.uk/Workshop/advice/coils/mu/index.html#bhcurve Unlike electrical conductivity, permeability is often a highly non-linear quantity. Most coil design formulę, however, pretend that it is a linear quantity. ========================================================= My question is- If I wind a transformer using the specified A sub L and then use that transformer in a receive antenna where the voltages are very small, wouldn't I be low on the curve and cause the transformer to function poorly especially at the lowest frequency of the design? Mike PS Thinking about a Flag antenna, which has a small output signal. Article: 223194 of rec.radio.amateur.antenna From: Roy Lewallen Subject: Re: Transforner Theory Date: Wed, 05 Apr 2006 19:51:33 -0700 Message-ID: <12390ho8oit9539@corp.supernews.com> References: <74ac6$44347c7f$45011502$11431@KNOLOGY.NET> amdx wrote: > Hi All, > > Info below from the following site---- > http://www.ee.surrey.ac.uk/Workshop/advice/coils/mu/index.html#bhcurve > > Unlike electrical conductivity, permeability is often a highly non-linear > quantity. Most coil design formulę, however, pretend that it is a linear > quantity. > > ========================================================= > > My question is- > > If I wind a transformer using the specified A sub L and then use that > transformer in a receive antenna where the voltages are very small, wouldn't > I be low on the curve and cause the transformer to function poorly > especially at the lowest frequency of the design? > > Mike > > PS Thinking about a Flag antenna, which has a small output signal. Al is usually the value for low flux density. That is, it's the value you'll have when the flux level is low. Permeability will drop from there at high flux levels. If you're making a broadband (untuned) transformer, you only need to insure that the winding impedance is high enough. If you design it to have adequate impedance at the lowest frequency, you should be ok for frequencies above that. If you're making a tuned transformer, you'll probably be using either powdered iron core or a ferrite core with a big air gap in the magnetic path like a ferrite rod. Either will withstand many orders of magnitude of flux density above what a received signal will produce before there's any noticeable change in permeability. The assumption of constant permeability is often a reasonable one. Change in permeability with flux density is certainly nothing you have to worry about in a receiving application unless you've got a lot of turns and a lot of DC current in the winding. Roy Lewallen, W7EL Article: 223195 of rec.radio.amateur.antenna Message-ID: <44348C60.D9909E41@earthlink.net> From: "Michael A. Terrell" Subject: Re: Question about auto antenna cable and connectors References: <443309E7.D3413253@earthlink.net> <12363o61bhj7g5e@corp.supernews.com> <44340C37.B9A3788D@earthlink.net> <12387jdrj3qgsd8@corp.supernews.com> Date: Thu, 06 Apr 2006 03:35:28 GMT Roy Lewallen wrote: > > Michael A. Terrell wrote: > > . . . > > One of the engineers at Delco told me it was RG-62, and 93 ohms when > > I was going to their annual car radio training back in the early '70s. > > IBM also used RG-62 on their coaxial computer networking, but they used > > BNC connectors. > > The automotive coax I'm familiar with isn't RG-62. > > Like automotive coax, RG-62 has a thin walled hollow insulating tube. > But RG-62 has a polyethylene "string" which is helically wound around > the center conductor to keep it centered in the hollow tube. The coax in > every old automotive installation I've seen lacks this PE "string", so > the center conductor is free to flop around inside the hollow tube. The > effect of the "string" is to make RG-62's Z0 constant and predictable, > and it will also increase the capacitance somewhat. Constant Z0 isn't > important for the automotive application, and low capacitance is important. > > It seems to me the center conductor is smaller in the automotive coax > than in RG-62, also. > > Roy Lewallen, W7EL I saw both types on car radio antennas, and some was clearly marked RG-62. Both types meet the original RG62 specification, they just use two different methods to minimize dielectric losses, like fused disk hardline used in CATV and other applications that require low loss cabling. Also, why would one of the Delco engineers who designed their car radios lie about the coax they used? He was explaining the then brand new AM/FM/8-track combo when I asked a number of questions about the RF front end. As usual, you will continue to believe whatever you want to. -- Service to my country? Been there, Done that, and I've got my DD214 to prove it. Member of DAV #85. Michael A. Terrell Central Florida Article: 223196 of rec.radio.amateur.antenna From: "Ken Bessler" References: <6wYYf.4689$fS6.618@dukeread11> Subject: Re: Unknown coax id help? Message-ID: <1h0Zf.4710$fS6.1223@dukeread11> Date: Wed, 5 Apr 2006 22:53:25 -0500 "Ed" wrote in message news:Xns979CC435E956Aspectrumhogstarbandn@198.186.192.196... > > > Maybe I'm wrong? Feel free to teach me. :-) > > > No, Ken, you're not wrong. I forgot you were only using a 5' > pigtail.... although you could probably get lower loss stuff. I don't > know what your application is, but you're right.... probably doesn't > matter that much. > > Ed I'm just trying to extend my wireless access point's range so I can go to a park nearby, operate /qrp/portable with my K2 yet still be able to check the dx cluster, email, etc. So far, I've equipped my ThinkPad with an Atheros high performance WiFi internal radio driving a pair of 4 element coaxial collinear antennas, acquired a V4 Linksys WRT54G router and designed & built a 16 element base version of the collinear antenna. I've got the needed parts enroute to put the base antenna up 25' and the firmware needed for the router to do all sorts of things, like, increase the TX power, go to client mode for rf survey's, stuff like that..... The pigtail antenna lead is just to make the transition from N connectors to the RP-TNC that the router uses and to protect the router from excess cable strain from the Flexi4xl coax. Just a way to spend money and kill time and - oh yea - learn some neat technology along the way. Next week, kids, we'll discuss the pro's and con's of 160 meter quad equipped diversity antenna systems....... lol! Ken KG0WX Article: 223197 of rec.radio.amateur.antenna From: "David G. Nagel" Subject: Re: Must 300 ohm feedline be kept completely clear of contact w anything? Date: Thu, 06 Apr 2006 00:37:28 -0500 Message-ID: <1239aaafdv8fa49@corp.supernews.com> References: Dave Oldridge wrote: > Thomas anonymous wrote in > news:Thomas.anonymous.25toz8@news.radiobanter.com: > > >>How critical is it to mount twinlead feedline (300 ohm TV ribbon type) >>so that it doesn't come into contact with anything? Obviously, with > > > You don't want unbalanced coupling between one side of the feedline and > something else. That would unbalance the feedline. You MAY not want the > impedance bump that comes with equal coupling on both sides, though that > might be tolerable if you're tuning the line anyway. And you don't want > lossy coupling of any kind. > In general there is a magnetic/electric field between the conductors in twinlead feed line. If this field is in contact with a metal or other conductive surface it will distort the impedance of the wire. Twinlead with the round surfaces between the conductors will keep the field out of the way of any surface the twinlead is resting on. This helps to maintain the constant 300 ohm impedance of the twinlead. That is why tv leadin uses standoffs to restrain the wire from the antenna to the receiver/transmitter. There is nothing wrong with using twinlead. It's cheap, light weight and easy to install. Dave WD9BDZ Article: 223198 of rec.radio.amateur.antenna From: Roy Lewallen Subject: Re: Transforner Theory Date: Wed, 05 Apr 2006 23:35:10 -0700 Message-ID: <1239dl1litgdfc5@corp.supernews.com> References: <74ac6$44347c7f$45011502$11431@KNOLOGY.NET> <12390ho8oit9539@corp.supernews.com> Larry Benko wrote: > Roy Lewallen wrote: > >> Al is usually the value for low flux density. That is, it's the value >> you'll have when the flux level is low. Permeability will drop from >> there at high flux levels. >> > > Not to nit-pick but the permeability of nearly all powdered iron > formulations actually rises with increasing flux levels (AC) and then > falls off. For #26 material (u=75), the effect is very much exagerated > with the permeability increasing nearly 300% at ~5000 Gauss and then > falling very quickly. However the permeability does drop for any value > of DC bias current and larger DC bias currents produce greater > reductions in permeability. > > 73, Larry Benko, W0QE Thanks for the correction. The permeability monotonically drops with increasing coercive force (H), but rises as you say with increasing flux density (B) over some range of flux densities. This is true for ferrites also. Roy Lewallen, W7EL Article: 223199 of rec.radio.amateur.antenna From: Roy Lewallen Subject: Re: Question about auto antenna cable and connectors Date: Wed, 05 Apr 2006 23:50:15 -0700 Message-ID: <1239ehalkdecf1c@corp.supernews.com> References: <443309E7.D3413253@earthlink.net> <12363o61bhj7g5e@corp.supernews.com> <44340C37.B9A3788D@earthlink.net> <12387jdrj3qgsd8@corp.supernews.com> <44348C60.D9909E41@earthlink.net> Michael A. Terrell wrote: > > I saw both types on car radio antennas, and some was clearly marked > RG-62. Both types meet the original RG62 specification, they just use > two different methods to minimize dielectric losses, like fused disk > hardline used in CATV and other applications that require low loss > cabling. Also, why would one of the Delco engineers who designed their > car radios lie about the coax they used? He was explaining the then > brand new AM/FM/8-track combo when I asked a number of questions about > the RF front end. As usual, you will continue to believe whatever you > want to. I happened to find a piece of the automotive cable -- complete with connector -- in my junk box, which I'm pretty sure was cut from a replacement antenna probably purchased in the '70s. This particular cable lacks the PE "string", but the ~#31 center conductor is crimped in a sort of zig-zag shape to keep it in place in the hollow tube. The aviation cable apparently has the center conductor bent into a (presumably loose) helix for the same purpose. I've never seen RG-62 cable without the PE "string", but don't have any trouble believing that someone might manufacture it without the "string". I also don't have trouble believing that some auto manufacturers might use RG-62. Although I saw a lot of auto installations in the '60s, when I moonlighted repairing such things, I never saw RG-62. But I certainly didn't see anywhere near every possibility, and I could have missed seeing a marking. Roy Lewallen, W7EL Article: 223200 of rec.radio.amateur.antenna From: Roy Lewallen Subject: Re: Must 300 ohm feedline be kept completely clear of contact w anything? Date: Wed, 05 Apr 2006 23:54:41 -0700 Message-ID: <1239epjqpmci573@corp.supernews.com> References: <1239aaafdv8fa49@corp.supernews.com> David G. Nagel wrote: > . . . > There is nothing wrong with using twinlead. It's cheap, light weight and > easy to install. When wet, it can become much lossier than RG-58. See http://www.eznec.com/Amateur/Articles/Portable_Feed_Lines.pdf. Roy Lewallen, W7EL Article: 223201 of rec.radio.amateur.antenna From: "stargatesg1" References: <4m_Yf.62380$H71.12519@newssvr13.news.prodigy.com> Subject: Re: building a yagi Message-ID: Date: Thu, 06 Apr 2006 07:04:08 GMT You can get aluminum 6061 3/16" rod at most metal suppliers or scrap metal salvage yards. Check the yellow pages. If they don't have it in stock they will usually order it for you. I was quoted a price of about $10 US for 1" X 12' square tubing, and about $3-4 for the 3/16" X 12' rod stock. Hope this helps, -- RoD "Steven Polczynski" wrote in message news:4m_Yf.62380$H71.12519@newssvr13.news.prodigy.com... > You can get aluminum tubing from an aircraft supplier. it comes in 12' > lengths. > > it would be a pretty expensive antenna but would last a long time. > > > "Leadfoot" wrote in message > news:hu3Uf.7382$lb.659961@news1.epix.net... > >I going to build a 11 element yagi but the problem I'm having is I can't > >find the aluminum rods, I was wondering if I use copper if I will still get > >the same Db gain. > > > > I was thinking of another metal was to use brake line from a car that I > > can get in the auto parts store. > > > > Thanks > > Ledfoot > > > > > > Article: 223202 of rec.radio.amateur.antenna From: ml Subject: pulse radio help Message-ID: Date: Thu, 06 Apr 2006 11:25:51 GMT hi Hoping someone might have read the same article (s) i did and can help me re find them I read somewhre mighta been nuts n volts pop electronics or pop sci ... was an article about a 1 guy, who invented a new type of radio transmission, called pulse width radio, NOT not to be confused w/the long avail current pwm stuff or pw stuff of today it alleged the technology could lead to cool things like hand held radar units , voice radios small sized that would work over large distances and use low power yah sounds great... next i heard the military was trying to steel his patents and then almost all reference to the work was gone it's gotta to have been at least 2yrs? no i can't find a trace of it anyplace anyone remember this 'news' and have any links to anything on the technology i could reference ?? thanks any help appreciated, realize it'a long shot but i hate not finding stuff Article: 223203 of rec.radio.amateur.antenna From: "Richard Fry" References: <44326790_1@newsfeed.slurp.net> <44329c0a_2@newsfeed.slurp.net> <4432a7f4_5@newsfeed.slurp.net> <2eb5329scje915brj9gmb9sd17ejvcvm9t@4ax.com> <4432d00b_4@newsfeed.slurp.net> <4433b845_3@newsfeed.slurp.net> <443422d4_4@newsfeed.slurp.net> <2gl83250938id6bp54hodrkenm2mffnoje@4ax.com> <4434655c_5@newsfeed.slurp.net> Subject: Re: Current across the antenna loading coil - from scratch Date: Thu, 6 Apr 2006 06:30:50 -0500 Message-ID: <4434fb26_5@newsfeed.slurp.net> "Richard Clark" wrote: >>On Tue, 4 Apr 2006 12:11:20 -0500, "Richard Fry" wrote: >> >>>The effective electrical length of a MW monople radiator determines its >>>resonant frequencies, and that must include the velocity of propagation >>>along the structure -- which is a function of the height AND width of the >>>radiator (mainly), and the operating frequency. > > Now, returning to the diameter that has been proven to be necessary to > resonate this instance which you dismiss as "ridiculous examples," my > comment about seeing very few towers that exhibit this magnitude of > diameter (the size of my living room) still stands as unimpeached. > > Going further into your cavalier dismissal of "ridiculous examples" we > find that there are a forest of very short antennas in service. My > link provides so many in one frequency assignment that the force of > numbers cannot be denied so simply, and certainly when lacking > technical rebuttal. Those offered such as WXNH 56.30° tall 540 kHz > when run through the same exercise above (YOUR reference, YOUR > claims) reveals a necessary A/D of LESS THAN 5. The simple math > resounds with the implications of necessary diameter to resonate this... ____________ You have seized and fixated on a concept I did not generate, ie, that AM broadcast antennas all need to be SELF-resonant, and that their L-D ratio is the way to achieve that. Anyone referencing my statement quoted above in this post, and thinking its does so has problems with reading comprehension. Why don't you just accept this reality, and move on? RF Article: 223204 of rec.radio.amateur.antenna From: Roy Lewallen Subject: Re: Velocity Factors Date: Thu, 06 Apr 2006 04:34:11 -0700 Message-ID: <1239v5lgcfjr823@corp.supernews.com> References: Some of the oval 300 ohm line, at least, was filled with PE foam. I think this was intended to keep the water out. Roy Lewallen, W7EL Reg Edwards wrote: > Has anyone ever measured the velocity factor of the twin feeder in > which the support for the wires is in the form of a plastic tube? > > I would guess the VF is quite high. There is no insulation directly > between the wires. > ---- > Reg. > > Article: 223205 of rec.radio.amateur.antenna From: "amdx" References: <74ac6$44347c7f$45011502$11431@KNOLOGY.NET> <12390ho8oit9539@corp.supernews.com> <1239dl1litgdfc5@corp.supernews.com> Subject: Re: Transforner Theory Date: Thu, 6 Apr 2006 07:02:53 -0500 Message-ID: <970b1$4435036d$45011502$7643@KNOLOGY.NET> "Roy Lewallen" wrote in message news:1239dl1litgdfc5@corp.supernews.com... > Larry Benko wrote: > > Roy Lewallen wrote: > > > >> Al is usually the value for low flux density. That is, it's the value > >> you'll have when the flux level is low. Permeability will drop from > >> there at high flux levels. > >> > > > > Not to nit-pick but the permeability of nearly all powdered iron > > formulations actually rises with increasing flux levels (AC) and then > > falls off. For #26 material (u=75), the effect is very much exagerated > > with the permeability increasing nearly 300% at ~5000 Gauss and then > > falling very quickly. However the permeability does drop for any value > > of DC bias current and larger DC bias currents produce greater > > reductions in permeability. > > > > 73, Larry Benko, W0QE > > Thanks for the correction. The permeability monotonically drops with > increasing coercive force (H), but rises as you say with increasing flux > density (B) over some range of flux densities. This is true for ferrites > also. > > Roy Lewallen, W7EL Please see the following URL Page 6, http://www.mag-inc.com/pdf/cg-01.pdf note the graph for the toroid, the inductance decreases by 40 percent going from 2000 gausse to 10 gausse. Question 1. I don't know where on that graph the published permeability would set the inductance. ( to clarify--How many gausse is used to measure permeability and set AL?) Question 2. Can anyone take a stab at how many gausse in a typical FT140-43 toroid with 8 turns on the secondary, and 34 or 35 turns on the primary used on a flag antenna with a low level signal. Maybe if we have two points on that graph we can have a real number to see how much inductance changes from published AL at low gausse. Mike PS. interesting how pot cores have very little inductance change with changing gausse. Article: 223206 of rec.radio.amateur.antenna From: mcalhoun@ksu.edu Subject: How get RF through a sealed window? Date: 6 Apr 2006 11:06:22 -0500 Message-ID: I gave a presentation on "How Ham Radio Can Help You in an Emergency" to 70 Emergency Management types last week, and the windows in the building which hosted the meeting were NOT open-able (so I "made do" with an inside VHF antenna and didn't even try to demonstrate HF). But in emergency/expedient situations, it would be really handy if one could pass at HF, say, 100 watts of RF energy through a window (I visualize some foil strips and an inductor or two to "tune out" the capacitance) to an external antenna. I've been told that the April, 1989, issue of Ham Radio magazine carried an article "Easy antenna access for urban apartment dwellers" (for 15 meters) by Bryan Bergeron, NU1N, starting on page 18. I'd sure like to read that article; can anyone send me a copy? -- --Myron A. Calhoun. Five boxes preserve our freedoms: soap, ballot, witness, jury, and cartridge PhD EE (retired). "Barbershop" tenor. CDL(PTXS). W0PBV. (785) 539-4448 NRA Life Member and Certified Instructor (Home Firearm Safety, Rifle, Pistol) Article: 223207 of rec.radio.amateur.antenna From: "David G. Nagel" Subject: Re: Must 300 ohm feedline be kept completely clear of contact w anything? Date: Thu, 06 Apr 2006 11:13:45 -0500 Message-ID: <123afiucu4h3i13@corp.supernews.com> References: <1239aaafdv8fa49@corp.supernews.com> <1239epjqpmci573@corp.supernews.com> Roy Lewallen wrote: > David G. Nagel wrote: > > . . . > >> There is nothing wrong with using twinlead. It's cheap, light weight >> and easy to install. > > > When wet, it can become much lossier than RG-58. See > http://www.eznec.com/Amateur/Articles/Portable_Feed_Lines.pdf. > > Roy Lewallen, W7EL Roy; True. Remember I said I don't use the stuff so I forgot that little tidbit. I also try not to use RG-58 for anything other than a mobile antenna and I am trying to get away from that also. Dave WD9BDZ Article: 223208 of rec.radio.amateur.antenna From: "David G. Nagel" Subject: Re: pulse radio help Date: Thu, 06 Apr 2006 11:16:29 -0500 Message-ID: <123afo2nncgu094@corp.supernews.com> References: ml wrote: > hi > > Hoping someone might have read the same article (s) i did and can help > me re find them > > I read somewhre mighta been nuts n volts pop electronics or pop sci > ... > > was an article about a 1 guy, who invented a new type of radio > transmission, called pulse width radio, NOT not to be confused w/the > long avail current pwm stuff or pw stuff of today > > it alleged the technology could lead to cool things like hand held > radar units , voice radios small sized that would work over large > distances and use low power yah sounds great... > > next i heard the military was trying to steel his patents and then > almost all reference to the work was gone > > it's gotta to have been at least 2yrs? no i can't find a trace of it > anyplace > > > anyone remember this 'news' and have any links to anything on the > technology i could reference ?? > > > thanks any help appreciated, realize it'a long shot but i hate not > finding stuff See the item in this newsgroup about "The Seven Warning Signs of Bogus Science"... Dave N Article: 223209 of rec.radio.amateur.antenna From: "sw monitor" Subject: Brandnew radio and transmitters massageboard Date: Thu, 6 Apr 2006 18:31:30 +0200 Message-ID: <4435441b$0$44281$dbd4b001@news.wanadoo.nl> Brandnew radio and transmitters massageboard After making the sw pirates group and the radio and transmitters group and not to forget the sw pirates forum a new forum is launched. a huge forum related to building radio, transmitters, ham and ameteur radio and so on, tip and moderators are very welcome, thes board needs promotion so webmasters, do your thing. any halp or placed URL's are welcome http://forum.alfalima.net/ geheel nieuw, een radio , zender en amateur radio forum, ook voor hulp bij je amateur opleiding, tips, idee's en moderators zeer welkom http://forum.alfalima.net/ Greetz Alfred Zoer Article: 223210 of rec.radio.amateur.antenna From: "Joel Kolstad" Subject: Re: How get RF through a sealed window? Date: Thu, 6 Apr 2006 10:59:36 -0700 Message-ID: <123alpjhjjbva3@corp.supernews.com> References: wrote in message news:e13e9u$q3u@unix1.cc.ksu.edu... > But in emergency/expedient situations, it would be really handy if one > could pass at HF, say, 100 watts of RF energy through a window (I > visualize some foil strips and an inductor or two to "tune out" the > capacitance) to an external antenna. In an emergency I'd say... uh... just leave the window open? :-) Over on eHam.net there's a recent article on building yourself a simple rectangular wooden panel to stick in the frame of an (open) window. You then just drive holes in the panel as needed to run cables, etc. I've even seen people who didn't have, e.g., a drill or jigsaw do the same thing using a thick-ish chunk of stiff foam (insulation material or even presentation poster board) and an X-acto knife. Article: 223211 of rec.radio.amateur.antenna From: Lawrence Statton N1GAK/XE1 Subject: Re: How get RF through a sealed window? Date: 06 Apr 2006 11:30:13 -0700 Message-ID: <87y7yieeve.fsf@hummer.i-did-not-set--mail-host-address--so-shoot-me> References: <123alpjhjjbva3@corp.supernews.com> "Joel Kolstad" writes: > wrote in message news:e13e9u$q3u@unix1.cc.ksu.edu... > > But in emergency/expedient situations, it would be really handy if one > > could pass at HF, say, 100 watts of RF energy through a window (I > > visualize some foil strips and an inductor or two to "tune out" the > > capacitance) to an external antenna. > > In an emergency I'd say... uh... just leave the window open? :-) But be sure to bring a hefty brick along to create the opening in the first place :) The OP's dilema was that the window COULD NOT open, and therefore some way to pass RF through glass would have been Useful. -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- Lawrence Statton - lawrenabae@abaluon.abaom s/aba/c/g Computer software consists of only two components: ones and zeros, in roughly equal proportions. All that is required is to sort them into the correct order. Article: 223212 of rec.radio.amateur.antenna From: "Cecil Moore" References: Subject: Re: How get RF through a sealed window? Message-ID: Date: Thu, 06 Apr 2006 18:44:48 GMT wrote: > But in emergency/expedient situations, it would be really handy if one > could pass at HF, say, 100 watts of RF energy through a window (I > visualize some foil strips and an inductor or two to "tune out" the > capacitance) to an external antenna. What I have done is plan ahead by drilling two small holes in the glass and plugging them with nylon screws when not in use. That works best on the first floor. :-) -- 73, Cecil, W5DXP Article: 223213 of rec.radio.amateur.antenna From: "Brian Murrey" References: Subject: Re: How get RF through a sealed window? Message-ID: Date: Thu, 06 Apr 2006 18:46:02 GMT You'd have better luck with HF than VHF or UHF making it through any solid object. I have used a homebrew mag loop in a hotel room on several ocassions with some luck..on 20 and 40. I have a 40m dipole in my attic, and I runn less than 5w HF most of the time and I have WAS on several ocassions, I try to WAS every year. 73 -- ========================================= Radio Amateurs - Fill your junk box, from my junkbox! http://www.hamradparts.com 73 de KB9BVN ========================================= wrote in message news:e13e9u$q3u@unix1.cc.ksu.edu... > I gave a presentation on "How Ham Radio Can Help You in an Emergency" > to 70 Emergency Management types last week, and the windows in the > building which hosted the meeting were NOT open-able (so I "made do" > with an inside VHF antenna and didn't even try to demonstrate HF). > > But in emergency/expedient situations, it would be really handy if one > could pass at HF, say, 100 watts of RF energy through a window (I > visualize some foil strips and an inductor or two to "tune out" the > capacitance) to an external antenna. > > I've been told that the April, 1989, issue of Ham Radio magazine carried > an article "Easy antenna access for urban apartment dwellers" (for 15 > meters) by Bryan Bergeron, NU1N, starting on page 18. > > I'd sure like to read that article; can anyone send me a copy? > -- > --Myron A. Calhoun. > Five boxes preserve our freedoms: soap, ballot, witness, jury, and cartridge > PhD EE (retired). "Barbershop" tenor. CDL(PTXS). W0PBV. (785) 539-4448 > NRA Life Member and Certified Instructor (Home Firearm Safety, Rifle, Pistol) Article: 223214 of rec.radio.amateur.antenna From: dplatt@radagast.org (Dave Platt) Subject: Re: How get RF through a sealed window? Date: Thu, 06 Apr 2006 19:05:48 -0000 Message-ID: <123apkcflafh49@corp.supernews.com> References: <123alpjhjjbva3@corp.supernews.com> <87y7yieeve.fsf@hummer.i-did-not-set--mail-host-address--so-shoot-me> In article <87y7yieeve.fsf@hummer.i-did-not-set--mail-host-address--so-shoot-me>, Lawrence Statton N1GAK/XE1 wrote: >But be sure to bring a hefty brick along to create the opening in the first >place :) > >The OP's dilema was that the window COULD NOT open, and therefore some >way to pass RF through glass would have been Useful. A lot of modern buildings have glass windows which not only cannot be opened, but which have a "low-E" (low thermal emission) coating on the glass. This is (I believe) a very thin layer of vapor-deposited metal. Its RF attenuation is considerable. Some years ago, we had our house windows (1960s-era glass) replaced with new ones using a low-E-coated glass. A previously-workable signal path for 802.11 signals, which got to the back of the house from an access point in the garage by going through the garage door and a couple of exterior windows, suddently became quite unusable - I had to install an additional access point to cover that part of the house. The more obviously shaded or reflective the glass, the more of a problem for RF transmission or coupling this stuff is likely to present. -- Dave Platt AE6EO Hosting the Jade Warrior home page: http://www.radagast.org/jade-warrior I do _not_ wish to receive unsolicited commercial email, and I will boycott any company which has the gall to send me such ads! Article: 223215 of rec.radio.amateur.antenna From: Allison-nospam@nouce.bellatlantic.net Subject: Re: Fiber Glass (shell) vs Metal Message-ID: <88ra32t07rq9p0ijb6qr6ro0nrpsj8n0gb@4ax.com> References: <1144345851.115512.302060@z34g2000cwc.googlegroups.com> Date: Thu, 06 Apr 2006 19:36:17 GMT On 6 Apr 2006 10:50:51 -0700, "Myles Byrne" wrote: >Been looking for a used 2 mtr ant. - was reading some comments about >Fiber Glass and Lightning - Someone said "Fiber Glass to lightning is >like a trailer park to a tornado" - "It's all metal on the inside" - >So, is there something to the comment ? Experience in commercial applications. Fiberglass radome antennas fair poorly with lightining hits, examples of such antennas were the rugged and very good "station master" series. I've personally seen two of these for VHF hi redused to a mount and fragments. All metal antennas like the quad dipole from DB products seemed to survive hits better as they are 99.9% metal all of which is grounded to the support. Allison Article: 223216 of rec.radio.amateur.antenna From: "amdx" References: <74ac6$44347c7f$45011502$11431@KNOLOGY.NET> <1144326826.706548.100400@g10g2000cwb.googlegroups.com> Subject: Re: Transforner Theory Date: Thu, 6 Apr 2006 14:58:37 -0500 Message-ID: wrote in message news:1144326826.706548.100400@g10g2000cwb.googlegroups.com... > > amdx wrote: > > > If I wind a transformer using the specified A sub L and then use that > > transformer in a receive antenna where the voltages are very small, wouldn't > > I be low on the curve and cause the transformer to function poorly > > especially at the lowest frequency of the design? > > > > Mike > > > > PS Thinking about a Flag antenna, which has a small output signal. > > Mike, > > > I think you are focusing on non-issues and not consider things that are > really important. > > First, I would not use a 43 core on a low frequency receive antenna. > This is especially true with an ungrounded antenna that has > exceptionally low signal output, like a Flag. > > There are very few antennas in the world that are perfectly UNbalanced > or perfectly balanced. Even what we consider an unbalanced antenna can > cause feed system problems. When the antenna has very low signal > output yet occupies a large spatial area, you are especially looking at > problems. > > The flag has low common mode impedance, and fairly high differential > mode impedance. It is neither balaunced nor unbalanced, it is in that > soupy world of something that requires equal and opposite currents at > the feed without perfect voltage balance. It is not a balanced antenna, > and not an unbalanced antenna. > > When that is combined with the very low signal output, you have to pay > particular attention to the transformer design. > > You really can't use a transmission line transformer because it will > not have enough isolation. You need a primary-secondary transformer > with isolated and slightly seperated windings. You really don't want a > material that requires 30 or 40 turns, because extra wire will increase > stray capacitance from primary to secondary. > > You almost certainly want to move into a binocular core with fairly > high permeability at the lowest frequency, like a 73 material. Unless > you have a few volts of RF from a closeby station, flux density is not > an issue. > > You want to keep primary/secondary capacitance down near a dozen pF or > less if possible, and have NO direct path for common mode currents. > > http://www.w8ji.com/k9ay_flag_pennant_ewe.htm > > 73 Tom > Hi Tom, Thanks for your input, When I wrote the above I couldn't remember what people were using on there flags so I went to one site and just copied what that site said, maybe it was a misprint and should have said 73. I used a 3F3 4229 pot core with 3 turns and 13 turns on my flag, I cut a styrofoam clamshell to go between the sec and pri to limit capacitance. I also put a grounded electrostatic shield between windings. I was happy with my nulls, (whatever that means;-) but wonder how efficient my transformer was. My questions still stand, Question 1 How many gausse is used to measure permeability and set AL? Question 2. Can anyone take a stab at how many gausse in a typical FT140-43 toroid with 8 turns on the secondary, and 34 or 35 turns on the primary used on a flag antenna with a low level signal. On the second question the material can be modified to reflect the material and turns as needed. Thanks Mike Article: 223217 of rec.radio.amateur.antenna From: mcalhoun@ksu.edu Subject: Re: How get RF through a sealed window? Date: 6 Apr 2006 15:07:17 -0500 Message-ID: References: <123alpjhjjbva3@corp.supernews.com> >> But in emergency/expedient situations, it would be really handy if one >> could pass at HF, say, 100 watts of RF energy through a window .... >Over on eHam.net there's a recent article on building yourself a simple >rectangular wooden panel to stick in the frame of an (open) window. You then >just drive holes in the panel as needed to run cables, etc.... I can just see me now: * Drive to the High-n-Mighty Hotel where I'm to provide communications for the Red Cross (or Salvation Army) shelter * Ask the desk clerk for someone to help me carry my sledgehammer and other stuff in my grab-n-go kit to the shelter * Walk into shelter where x-hundred shelterees are fast asleep * Take sledgehammer and bash a hole through a window * .... Nope, that's just not gonna work! -- --Myron A. Calhoun. Five boxes preserve our freedoms: soap, ballot, witness, jury, and cartridge PhD EE (retired). "Barbershop" tenor. CDL(PTXS). W0PBV. (785) 539-4448 NRA Life Member and Certified Instructor (Home Firearm Safety, Rifle, Pistol) Article: 223218 of rec.radio.amateur.antenna From: mcalhoun@ksu.edu Subject: Re: How get RF through a sealed window? Date: 6 Apr 2006 15:13:53 -0500 Message-ID: References: >You'd have better luck with HF than VHF or UHF making it through any solid >object. I have used a homebrew mag loop in a hotel room on several >ocassions with some luck..on 20 and 40. Even in an emergency situation, I just don't think it would be a good idea to string some kind of an antenna above the heads of shelterees and then start soaking them with RF, especially depending on the HF frequency in use. In fact, I suspect the FCC's RF-exposure regulations would frown on one doing so! -- --Myron A. Calhoun. Five boxes preserve our freedoms: soap, ballot, witness, jury, and cartridge PhD EE (retired). "Barbershop" tenor. CDL(PTXS). W0PBV. (785) 539-4448 NRA Life Member and Certified Instructor (Home Firearm Safety, Rifle, Pistol) Article: 223219 of rec.radio.amateur.antenna From: Roy Lewallen Subject: Re: Transforner Theory Date: Thu, 06 Apr 2006 13:33:14 -0700 Message-ID: <123auob9ii13c8c@corp.supernews.com> References: <74ac6$44347c7f$45011502$11431@KNOLOGY.NET> <1144326826.706548.100400@g10g2000cwb.googlegroups.com> amdx wrote: > . . . > My questions still stand, > Question 1 > How many gausse is used to measure permeability and set AL? Essentially zero. > Question 2. > Can anyone take a stab at how many gausse in a typical FT140-43 toroid > with 8 turns on the secondary, and 34 or 35 turns on the primary used on a > flag antenna with a low level signal. I won't bother to calculate it because the change in permeability would be so small you wouldn't be able to measure it. This is a non-problem; you're wasting your time worrying about it. > On the second question the material can be modified to reflect the material > and turns as needed. If your circuit is sensitive to a change in a few parts per million of permeability, it has serious problems. The permeability will change several orders of magnitude more than that with modest changes in temperature. Roy Lewallen, W7EL Article: 223220 of rec.radio.amateur.antenna From: aRKay Subject: Re: HDTV Antennas References: <030420062013148840%artie.m@gNOSPAMmail.com> Message-ID: Date: Thu, 06 Apr 2006 20:34:47 GMT In article <030420062013148840%artie.m@gNOSPAMmail.com>, artie wrote: > In article > , aRKay > wrote: > > > What is unique about the new HDTV antennas? We just picked up a new > > HDTV with a tuner and was advised to pickup a simple HDTV antenna to > > pick up the local digital broadcast. Any magic to these other the high > > gain claims on the boxes? > > > > Dick AA5VU > > Last I looked, broadcast HDTV occupies the old UHF tv channels, so... > > Rat Shack Model: U-75R, Catalog #: 15-2160 $25 > > it's a UHF antenna, nothing more, and that's all you need. I've put in > a few of these. I am 3 to 4 miles from the transmission towers and the antenna you mentioned may be too directional. I need an omnidirectional UHF only. Article: 223221 of rec.radio.amateur.antenna Message-ID: <4435804C.B3342CE2@earthlink.net> From: "Michael A. Terrell" Subject: Re: Question about auto antenna cable and connectors References: <443309E7.D3413253@earthlink.net> <12363o61bhj7g5e@corp.supernews.com> <44340C37.B9A3788D@earthlink.net> <12387jdrj3qgsd8@corp.supernews.com> <44348C60.D9909E41@earthlink.net> <1239ehalkdecf1c@corp.supernews.com> Date: Thu, 06 Apr 2006 20:56:34 GMT Roy Lewallen wrote: > > Michael A. Terrell wrote: > > > > I saw both types on car radio antennas, and some was clearly marked > > RG-62. Both types meet the original RG62 specification, they just use > > two different methods to minimize dielectric losses, like fused disk > > hardline used in CATV and other applications that require low loss > > cabling. Also, why would one of the Delco engineers who designed their > > car radios lie about the coax they used? He was explaining the then > > brand new AM/FM/8-track combo when I asked a number of questions about > > the RF front end. As usual, you will continue to believe whatever you > > want to. > > I happened to find a piece of the automotive cable -- complete with > connector -- in my junk box, which I'm pretty sure was cut from a > replacement antenna probably purchased in the '70s. This particular > cable lacks the PE "string", but the ~#31 center conductor is crimped in > a sort of zig-zag shape to keep it in place in the hollow tube. The > aviation cable apparently has the center conductor bent into a > (presumably loose) helix for the same purpose. I've never seen RG-62 > cable without the PE "string", but don't have any trouble believing that > someone might manufacture it without the "string". I also don't have > trouble believing that some auto manufacturers might use RG-62. Although > I saw a lot of auto installations in the '60s, when I moonlighted > repairing such things, I never saw RG-62. But I certainly didn't see > anywhere near every possibility, and I could have missed seeing a marking. > > Roy Lewallen, W7EL Some of the third party replacement antennas were made with military surplus RG62, and had hand soldered motorola plugs instead of the OEM crimped plugs. I cut up a lot of old antenna cables and stripped the copper braid to use as solder wick by dipping it into liquid rosin. Some had the plastic spacer for the center conductor, but most didn't. Some weeks we replaced a half dozen car radio antennas, so I always had plenty of copper braid at hand. years later I worked for a CATV company repairing converters. The braid from the control cables was a little under 1/8" when it was pulled tight and flattened by pulling it around the blade of a screwdriver. -- Service to my country? Been there, Done that, and I've got my DD214 to prove it. Member of DAV #85. Michael A. Terrell Central Florida Article: 223222 of rec.radio.amateur.antenna From: "Joel Kolstad" Subject: Re: How get RF through a sealed window? Date: Thu, 6 Apr 2006 14:49:11 -0700 Message-ID: <123b38gspg7kg65@corp.supernews.com> References: <123alpjhjjbva3@corp.supernews.com> <87y7yieeve.fsf@hummer.i-did-not-set--mail-host-address--so-shoot-me> "Lawrence Statton N1GAK/XE1" wrote in message news:87y7yieeve.fsf@hummer.i-did-not-set--mail-host-address--so-shoot-me... > The OP's dilema was that the window COULD NOT open, and therefore some > way to pass RF through glass would have been Useful. Oops, sorry I missed that! Article: 223223 of rec.radio.amateur.antenna From: "oli" Subject: DELTA LOOP antenna calculator now work with MMANA Date: Fri, 7 Apr 2006 00:08:10 +0200 Message-ID: <4435914e$0$21278$8fcfb975@news.wanadoo.fr> Good morning, I'am happy to tell you that the delta loop antenna calculator http://www.antenna-street.com/delta-loop-1en.php can now generate automatiquely the .maa file from your values. It is operationnal for each delta loop on 10-11 meters band and from 2 to 6 elements. This will be online in few hours and hope that MMANA users could give their opinion. best regards oli Article: 223224 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Current across the antenna loading coil - from scratch References: <1143142526.021154.67050@e56g2000cwe.googlegroups.com> <0hf13258667d7d0m648bf6rbgm6ecrj2sl@4ax.com> <5qaYf.6$qO.0@fe10.lga> <1144131328.322721.32520@t31g2000cwb.googlegroups.com> <1k5532h8scbtg8e8iscn4ncjuusoa7ddai@4ax.com> Message-ID: Date: Thu, 06 Apr 2006 22:57:48 GMT Ian White GM3SEK wrote: > Based entirely on what you yourself have written, I have told you that > you don't understand something. Unless you can prove you are omniscient, Ian, the problem could possibly be with your misunderstanding of something, not mine. % along current in current in wire #2 TravWave.EZ StndWave.EZ 0.28% 0.9998 at -0.99 deg 0.9996 at 0 deg 9.72% 0.9983 at -9.39 deg 0.9843 at -0.03 deg 19.7% 0.9969 at -18.23 deg 0.9454 at -0.05 deg 30.3% 0.9957 at -27.59 deg 0.8843 at -0.06 deg 39.7% 0.9949 at -35.96 deg 0.8023 at -0.08 deg 49.7% 0.9945 at -44.84 deg 0.7014 at -0.09 deg 60.3% 0.9945 at -54.20 deg 0.5840 at -0.09 deg 69.7% 0.9949 at -62.58 deg 0.4528 at -0.10 deg 79.7% 0.9956 at -71.43 deg 0.3110 at -0.11 deg 89.7% 0.9965 at -80.27 deg 0.1616 at -0.11 deg 99.7% 0.9976 at -89.14 deg 0.0061 at -0.11 deg My EZNEC data posting proves that EZNEC correctly predicts the differences in the traveling wave current and the standing wave current. I'm building a new web page around those results. I have graphed the EZNEC results and they are available at: http://www.qsl.net/w5dxp/travstnd.GIF Please note that the traveling wave magnitude looks like the standing wave phase and the traveling wave phase looks like the standing wave magnitude. Anyone who maintains that there is no difference between a traveling wave current and a standing wave current should take a long close look. The corresponding EZNEC files are available at: http://www.qsl.net/w5dxp/TravWave.EZ http://www.qsl.net/w5dxp/StndWave.EZ -- 73, Cecil http://www.qsl.net/w5dxp