Article: 219690 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: SWR again. References: <1efpo153ju7lgkn5hai1otaifo83rqi3u0@4ax.com> <3fkpo1578sa6nejfr47umsq10d970jqjkc@4ax.com> <0k0so1hqr95fd08kelufhnn07a3mkk72s9@4ax.com> <1c8so1tpnnqmn2at06s2djk2k240bco793@4ax.com> Message-ID: Date: Thu, 01 Dec 2005 13:29:21 GMT Owen Duffy wrote: > Now, you're trying to trick me... did you mean Wireman 554? Yep, no trick, just tricky fingers, getting worse with age. > The 0.9dB stated earlier was (as stated) for 552 which had a Zo closer > to your 380 ohms, whereas 554 is 360 ohms. I measured the 554 at 380 ohms. I could have been off by 5%. > Given that some radios (including the IC706-IIG) reduce drive power at > high VSWR as a protection mechanism, you may want to install an ATU to > develop full power output. My recollection is that the power output of > the IC706-IIG is significantly down at VSWR=2, but it probably also > depends on the actual load impedance. I have never witnessed my IC-706 folding back at any resistive load between 25 ohms and 100 ohms. My IC-706 manual says, "When the SWR is *higher* than approx. 2.0:1, the transceiver's power drops to protect the final transistors." -- 73, Cecil http://www.qsl.net/w5dxp Article: 219691 of rec.radio.amateur.antenna From: "Jeff Dieterle" Subject: Re: Am Antenna Help Date: Thu, 1 Dec 2005 08:39:08 -0500 Message-ID: <11otv7q7vq0a450@corp.supernews.com> References: <11oos4qo1fo1dd2@corp.supernews.com> <11orh6rkdfkqj6a@corp.supernews.com> >>> You never mention how far away you are from "... Indianapolis 1070kc and >>> Chicago 670kc & 1000kc." That'll have a LARGE bearing on the day/night >>> reception question. >>> >>> Jonesy >>> -- >>> Marvin L Jones | jonz | W3DHJ | linux >>> Pueblo, Colorado | @ | Jonesy | OS/2 __ >>> 38.24N 104.55W | config.com | DM78rf | SK I'm 70mi from Indy and 120mi from Chicago. Chicago 670kc is reasonable at night 1070kc out of Indy at night is pretty bad. Is 40ft at right angles to these signals better that 200ft parallel? Terry wrote: > One wavelength at a frequency of say 1070 kcs is a little less than 300 > metres (approx 1000 feet?). > An antenna of either length will be very 'short' compared to the > 'wavelengths' involved and will not be close to resonance. > e.g. For quarter wave resonance (approx 75 metres or about 250 feet; for > 1070 kcs and nearly 400 feet for say 670 kcs ) required. > Any 'too short' antenna will be will be badly mismatched (energy loss!) to > the impedance of the co-ax. > This suggest that some kind of untuned impedance matching transformer, > suitable for the frequencies in question, might be used to transfer as > much energy as possible to the co-ax transmission line? > Seen this done with short 'whip' antenna operating at Broadcast > Band/Medium Wave frequencies. > Transmission line should also be matched at the receiver end? > 100 feet of coax at those frequencies should have low loss? any guidance on how I accomplish above impedance matching thanks in advance jeff Article: 219692 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: MFJ-269 Antenna/SWR/RF Analyzer References: <9stto19tjms8ie9qbb6j825h18l9rdu39u@4ax.com> Message-ID: Date: Thu, 01 Dec 2005 13:41:01 GMT John Ferrell wrote: > It is amazing what you can learn about an antenna in such a short > time! My MFJ-259B is a really handy little gadget for learning. So is EZNEC. -- 73, Cecil http://www.qsl.net/w5dxp Article: 219693 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: using a model References: <438F101C.8070503@comcast.net> Message-ID: Date: Thu, 01 Dec 2005 15:19:38 GMT dansawyeror wrote: > William Orr wrote that a cross mesh under an HF vertical > approximated a perfect ground. That's only where the mesh is installed. Ground reflections and attenuation extend beyond the mesh area. How high above the mesh are you going to position the 2m antenna? -- 73, Cecil, http://www.qsl.net/w5dxp Article: 219694 of rec.radio.amateur.antenna From: Phil Wheeler Subject: Re: using a model References: <438F101C.8070503@comcast.net> Message-ID: Date: Thu, 01 Dec 2005 16:02:56 GMT Cecil Moore wrote: > dansawyeror wrote: > >> William Orr wrote that a cross mesh under an HF vertical approximated >> a perfect ground. > > I've put up complete antenna systems that seem to approximate a perfect ground .. some of them commercial products :) Article: 219695 of rec.radio.amateur.antenna From: "Harold E. Johnson" References: <1133454210.047291.209170@g44g2000cwa.googlegroups.com> Subject: Re: Ground-Level HF Beam Tuning? Message-ID: Date: Thu, 01 Dec 2005 16:42:28 GMT > I've seen suggestions here and there about simply aiming a beam > vertically upward and doing all the tuning at ground level instead. > Which would save an awful lot of time and effort. If it works. Does > anybody around here have any experience with this method and if so how > succesful was it? > > Thanks, > > Brian w3rv Works fine with a yagi, I've always just lashed a 2 x 4 to the tower and "hung" the antenna off the side of the tower pointed straight up. There's a null off the bottom of the yagi, and it ignores the tower as well. Not sure of the topology of your "hexbeam" thingie, but if you can get it to ignore things around it, the reflector, if it's doing any reflecting at all, will remove the ground from the tuning process. W4ZCB > Article: 219696 of rec.radio.amateur.antenna From: nospam@nouce.bellatlantic.net Subject: Re: Ground-Level HF Beam Tuning? Message-ID: References: <1133454210.047291.209170@g44g2000cwa.googlegroups.com> Date: Thu, 01 Dec 2005 17:09:50 GMT On 1 Dec 2005 08:23:30 -0800, "Brian Kelly" wrote: >I'm mulling the design/homebrewing of a hexagonal 20/17/15/12/10M wire >beam a la the Traffie Hexbeam. The problem with just about all projects >like this is the number of up/down iterations required to tweak the >tuning of the things. Put it up, calculate the required changes in >element lengths, take it down, make the adjustments, put it back up to >check it again, pull it down and go thru the whole cycle ad nauseam. >Pain in the tush. > >I've seen suggestions here and there about simply aiming a beam >vertically upward and doing all the tuning at ground level instead. >Which would save an awful lot of time and effort. If it works. Does >anybody around here have any experience with this method and if so how >succesful was it? > >Thanks, > >Brian w3rv It will get you close. However it really depends on the front to back of the antenna. Dipoles do poorly this way, 2 element beams slightly better. I've done 3 element 6m beams with the reflector only 4ft off the ground pointing up with excellent success. Seems the breakpoint is some where around better than 10or 12 DB F/B ratio. You do need distance from the ground or it acts like a reflector and messes with your measurments. Allison Article: 219697 of rec.radio.amateur.antenna From: "Asimov" Subject: Re: C. Crane's Twin Ferrite Antenna Message-ID: References: <8Kzjf.84363$QM5.38523@tornado.socal.rr.com> Date: Thu, 01 Dec 2005 17:11:04 GMT "Phil Wheeler" bravely wrote to "All" (01 Dec 05 09:53:08) --- on the heady topic of "Re: C. Crane's Twin Ferrite Antenna" PW> From: Phil Wheeler PW> Xref: core-easynews rec.radio.amateur.antenna:220688 PW> BKR wrote: > Computers and computer components are regulated by the FCC. > They MUST NOT cause interferance to licenced radio services. > (like the radio stations you are trying to tune in.) > Make that clear to the vendor you got the power supply from! PW> Interesting thought but impractical. It could be the installation PW> (e.g., grounding) vs. the supply itself. Event if the PSU itself, PW> proving it would be a chore. Especially since most of the off-shore stuff may have all the right stickers but be complete fakes of the real thing. A*s*i*m*o*v ... We're young, rich, and full of sugar, what do we do? Article: 219698 of rec.radio.amateur.antenna From: "kd5sak" References: <1133454210.047291.209170@g44g2000cwa.googlegroups.com> Subject: Re: Ground-Level HF Beam Tuning? Message-ID: Date: Thu, 01 Dec 2005 17:19:04 GMT "Brian Kelly" wrote in message news:1133454210.047291.209170@g44g2000cwa.googlegroups.com... > I'm mulling the design/homebrewing of a hexagonal 20/17/15/12/10M wire > beam a la the Traffie Hexbeam. The problem with just about all projects > like this is the number of up/down iterations required to tweak the > tuning of the things. Put it up, calculate the required changes in > element lengths, take it down, make the adjustments, put it back up to > check it again, pull it down and go thru the whole cycle ad nauseam. > Pain in the tush. > > I've seen suggestions here and there about simply aiming a beam > vertically upward and doing all the tuning at ground level instead. > Which would save an awful lot of time and effort. If it works. Does > anybody around here have any experience with this method and if so how > succesful was it? > > Thanks, > > Brian w3rv > Another local Ham and I have built two monoband 20 meter versions of the HexBeam utilizing info from W1GQLs hexbeam website (one with PVC spreaders and one with fiberglass rod spreaders). Neither had to be adjusted at all after the original wire length was cut. Mine has usable tuning at just above ground level and it's expected to get only better with height, as the other one did. Granted, we didn't have the other band elements to fuss with. If you can get element lengths and vertical separation distances from someone with a working multibander chances are you won't need to do any adjusting on those, either. W1GQL has suggested, with the finite lifespan of such antennas and the current lowpoint of the sunspot cycle, that there is no overwhelming need for 10, 12, and 15 meter elements for at least the next couple of years. You might try building your antenna as a monoband 20 meter, but construct the antenna with sufficient spreader tension and bow depth that you can later add additional bands. The foregoing advice is free and not necessarily valuable, but is given with friendly intent.(G) My own fiberglass HexBeam has a 30" bow depth and I may yet attempt to add a band or two later. Good luck with yours however you choose to build it. Harold KD5SAK Article: 219699 of rec.radio.amateur.antenna From: "AAA RF Products" Subject: Free Catalog: Coax Cable, Connectors & Adapters Message-ID: Date: Thu, 1 Dec 2005 10:08:27 -0800 For your free copy of our new catalog, please email sales@AAARFProducts.com or see www.aaarfproducts.com or call 949 481 3154 (San Clemente, CA) No minimum order. No handling charges. Article: 219700 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: 30/20 vertical? References: <1133023175.424981.104610@g43g2000cwa.googlegroups.com> <%w2if.33945$6e1.9744@newssvr14.news.prodigy.com> <1133457598.727325.128180@g47g2000cwa.googlegroups.com> Message-ID: Date: Thu, 01 Dec 2005 19:01:00 GMT nm5k@wt.net wrote: > I'm wondering > if a short vertical with long elevated radials would result > in an "off-center-fed" vertical. > > Not the way I see it, just as long as all the radials are > equal length. The reason I don't see it, is the radiation of the > radials should pretty much cancel if all are equal. Not > quite the same as the single radial in that situation. > If you had one radial, maybe so... I just ran one on EZNEC. The feedpoint is at 23 feet and there are four 23 foot radials drooping at 45 degrees. (I already had this one modeled.) With a 23 foot vertical section, the feedpoint resistance is 56 ohms on 10.2 MHz. 234/10.2 = 23 feet With a 12 foot vertical section, the feedpoint resistance is 84 ohms on 16.4 MHz. 234/16.4 = 14.2 feet, 2.2' longer than 12'. It looks like (with slanted radials that radiate) there is an "off-center-feed" effect, i.e. longer radials require a shortened vertical section. -- 73, Cecil, http://www.qsl.net/w5dxp Article: 219701 of rec.radio.amateur.antenna From: Roy Lewallen Subject: Re: using a model Date: Thu, 01 Dec 2005 11:27:16 -0800 Message-ID: <11oujkns4rgt0ca@corp.supernews.com> References: <11otcudpfmj6096@corp.supernews.com> <438F0DDB.1080407@comcast.net> dansawyeror wrote: > Roy, > > Thank you. My first objective is hopefully relatively simple. I would > like to determine resonance and measure Z. In order to do that I will > use an HP 8405A and directional couplers. Your suggestion is to practice > that on known antennas. That makes sense. Given that I have relatively > good generators and can measure forward and reflected signals at the > antenna, is that sufficient to measure model impedance? Provided that you can measure phase as well as amplitude, both with adequate accuracy, and know how to establish a reference plane by either calibration or calculation. It's not simple. Roy Lewallen, W7EL Article: 219702 of rec.radio.amateur.antenna From: Roy Lewallen Subject: Re: using a model Date: Thu, 01 Dec 2005 11:35:27 -0800 Message-ID: <11ouk434sa7itcd@corp.supernews.com> References: <438F101C.8070503@comcast.net> dansawyeror wrote: > Where can I learn about the difference in ground characteristics between > 75m and 2m? . . . If you want to model 75m ground, you need to begin with what you assume the ground characteristics to be at 75m. Let's say you have average ground, with conductivity of 5 mS/m and dielectric constant of 13. For your model, you'll need something with conductivity of 5 * 146/3.8 ~ 192 mS/m conductivity and dielectric constant of 13. I have no idea where you might find such a material. >William Orr wrote that a cross mesh under an HF vertical > approximated a perfect ground. It should be relatively easy to do the > same under a 2m model. I assume that metal reference ground would react > the same. No problem approximating a perfect ground. If you have a perfect ground under your 75 meter antenna, it won't be hard to make a decent model of the perfect ground. A piece of screen or hardware cloth would do fine. The trick will be making that perfect ground under your 75 meter antenna. And unless you do, the model won't behave the same as the real antenna. Roy Lewallen, W7EL Article: 219703 of rec.radio.amateur.antenna From: richardharrison@webtv.net (Richard Harrison) Subject: Re: Antenna reception theory Date: Thu, 1 Dec 2005 14:18:33 -0600 Message-ID: <26586-438F5A99-1152@storefull-3253.bay.webtv.net> References: <11opb3rakuceo3d@corp.supernews.com> Roy Lewallen wrote: "You can find the explanation for why this is in any electromagnetic text." I found it in Terman. As we all know, we place correctly polarized dipoles, for example, parallel to the wavefront for maximum response. Terman confirms the electric field in this instance induces no energy in the antenna. It all comes from the magnetic field. If antenna current flows, no matter where it comes from, loss resistance causes a voltge drop. That`s why the wire needs to be perfect. The electric field produces no voltage in the antenna because the wavefront has the same voltage across its entire surface. That`s because it all left the same point at the same time. So, a wire parallel to the front has no difference of potential induced by the wavefront`s electric field. It all must come from the mgnetic field. On page 2 of his 1955 edition, Terman says: "The strength of the wave measured in terms of microvolts per meter of stress in space is also exactly the same voltage that the MAGNETIC FLUX (my emphasis) of the wave induces in a conductor 1 m long when sweeping across this conductor with the velocity of light." >From the above, it is seen that the electric field is not effective in inducing current in a receiving antenna parallel to a wavefront. All the energy intercepted by the antenna is induced by the magnetic field. Best regards, Richard Harrison, KB5WZI Article: 219704 of rec.radio.amateur.antenna From: Roy Lewallen Subject: Re: Antenna reception theory Date: Thu, 01 Dec 2005 14:07:05 -0800 Message-ID: <11out0c5oh6ghd6@corp.supernews.com> References: <11opb3rakuceo3d@corp.supernews.com> <26586-438F5A99-1152@storefull-3253.bay.webtv.net> It looks like time to remind readers that charge isn't the same as electrons. On a wire, charge moves at nearly the speed of light, while electrons only go a few miles per hour. Most of the relevant theory actually deals with the interaction of fields and charge, not fields and electrons. Roy Lewallen, W7EL Article: 219705 of rec.radio.amateur.antenna From: mcalhoun@ksu.edu Subject: OFF TOPIC, but how do y'all read these news groups? Date: 1 Dec 2005 16:02:04 -0600 Message-ID: Note the multi-group posting. For 18 years, I've been reading newgroups on Unix (or Linux) machines, first using "rn" (readnews) and later "nn" (netnews), but now my ISP (Kansas State University) has notified me that, because their news server is getting old and because I'm one of only a very few users, they are dropping the service as of 28 December. So I need to find an alternative way of getting my daily "fix"; I sure hope someone has suggestion(s)! -- --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: 219706 of rec.radio.amateur.antenna Date: Thu, 01 Dec 2005 18:36:05 -0400 From: Bill Subject: Re: OFF TOPIC, but how do y'all read these news groups? References: <43a463-5ld.ln1@remote.clifto.com> Message-ID: <5ff07$438f7ad6$4232bd6c$7468@COQUI.NET> clifto wrote: > mcalhoun@ksu.edu wrote: > >>So I need to find an alternative way of getting my daily "fix"; >>I sure hope someone has suggestion(s)! > > > You can buy a super duper feed from Supernews. For less money, you can > get a good feed (text only IIRC) from news.individual.net. > > Guess we're not in Kansas any more. > add teranews.com to the list Article: 219707 of rec.radio.amateur.antenna From: Jim Kelley Subject: Re: Antenna reception theory Date: Thu, 01 Dec 2005 14:35:27 -0800 Message-ID: References: <11opb3rakuceo3d@corp.supernews.com> <26586-438F5A99-1152@storefull-3253.bay.webtv.net> <11out0c5oh6ghd6@corp.supernews.com> Roy Lewallen wrote: > It looks like time to remind readers that charge isn't the same as > electrons. On a wire, charge moves at nearly the speed of light, while > electrons only go a few miles per hour. Most of the relevant theory > actually deals with the interaction of fields and charge, not fields and > electrons. > > Roy Lewallen, W7EL Good point. Charge can be holes, or electrons, or even ions. It is the fields which move at the speed of light. Charge tends to have to hang around with the charge carriers. But once a field arrives someplace, it will immediately influence the motion of charges that happen to be hanging around there locally. ac6xg Article: 219708 of rec.radio.amateur.antenna From: "John, N9JG" References: <43a463-5ld.ln1@remote.clifto.com> <5ff07$438f7ad6$4232bd6c$7468@COQUI.NET> Subject: Re: OFF TOPIC, but how do y'all read these news groups? Message-ID: Date: Thu, 01 Dec 2005 22:40:48 GMT Check out https://www.altopia.com/ "Bill" wrote in message news:5ff07$438f7ad6$4232bd6c$7468@COQUI.NET... > clifto wrote: > >> mcalhoun@ksu.edu wrote: >> >>>So I need to find an alternative way of getting my daily "fix"; >>>I sure hope someone has suggestion(s)! >> >> >> You can buy a super duper feed from Supernews. For less money, you can >> get a good feed (text only IIRC) from news.individual.net. >> >> Guess we're not in Kansas any more. >> > add teranews.com to the list Article: 219709 of rec.radio.amateur.antenna From: John Ferrell Subject: Re: MFJ-269 Antenna/SWR/RF Analyzer Message-ID: References: <9stto19tjms8ie9qbb6j825h18l9rdu39u@4ax.com> Date: Thu, 01 Dec 2005 23:24:52 GMT I agree. I took the ARRL course using EZNEC and cannot praise it enough! On Thu, 01 Dec 2005 13:41:01 GMT, Cecil Moore wrote: >John Ferrell wrote: >> It is amazing what you can learn about an antenna in such a short >> time! > >My MFJ-259B is a really handy little gadget for learning. >So is EZNEC. John Ferrell W8CCW Article: 219710 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: OFF TOPIC, but how do y'all read these news groups? References: Message-ID: Date: Thu, 01 Dec 2005 23:32:26 GMT mcalhoun@ksu.edu wrote: > So I need to find an alternative way of getting my daily "fix"; > I sure hope someone has suggestion(s)! Who's your ISP? SBCGlobal.net supplies a news-server. Google's newsgroup server is now close to real-time. Or try: > http://www.usenet-access.com/contactus.asp -- 73, Cecil http://www.qsl.net/w5dxp Article: 219711 of rec.radio.amateur.antenna From: kludge@panix.com (Scott Dorsey) Subject: Re: OFF TOPIC, but how do y'all read these news groups? Date: 1 Dec 2005 18:42:46 -0500 Message-ID: References: In article , wrote: >For 18 years, I've been reading newgroups on Unix (or Linux) machines, >first using "rn" (readnews) and later "nn" (netnews), but now my ISP >(Kansas State University) has notified me that, because their news server >is getting old and because I'm one of only a very few users, they are >dropping the service as of 28 December. If you like using the old rn, nn, and tin servers, get a shell account >from Panix. You can telnet or ssh in from anywhere in the world, type "rn" at the shell prompt and go. And it's ten bucks a month and the tech support is better than you've ever had from Computer Services at KSU. --scott -- "C'est un Nagra. C'est suisse, et tres, tres precis." Article: 219712 of rec.radio.amateur.antenna From: Bob Miller Subject: Re: Mobile 2m/70cm antenna Message-ID: References: <11orv408qms0pfd@corp.supernews.com> Date: Fri, 02 Dec 2005 01:05:59 GMT On Wed, 30 Nov 2005 11:24:47 -0800, "Rod Maupin" wrote: >I recently bought a Larsen 2m/70cm NMO mag-mount mobile antenna for my >truck. It's the first time I've ever owned a mobile antenna because I don't >do that much driving (I work from home). I don't have a mobile radio in the >truck, I just have an HT. > >What I wanted to do was hook up my Icom W32A to the mobile antenna when I'm >in the truck. So, I put the mag-mount on the middle of the pickup roof and >started driving. I compared the mobile Larsen antenna to my Diamond RH77CA >HT antenna. What I noticed is that with the Diamond antenna on the HT >inside the truck, it consistently pulls in more signal (on both bands) than >the Larsen mobile outside the truck. The Diamond antenna is of course an HT >antenna, so it's optimized for HT use. > >Is this normal behavior for a mobile antenna hooked up to an HT? If it's >not normal, then this is not that great of a mobile antenna. > >Rod KI7CQ > When I bought a similar antenna, a Larsen 2m/70cm mag mount (mine is about 20 years old, but may be the same exact model as yours) anyhow, I had to cut the vertical element with a file to get the SWR down, using a Bird wattmeter. The antenna, as it came from the factory, needed quite a bit of diddling before being resonant. Have you checked SWR, and/or adjusted the vertical length? Bob k5qwg Article: 219713 of rec.radio.amateur.antenna From: Ken Scharf Subject: Re: OFF TOPIC, but how do y'all read these news groups? References: <43a463-5ld.ln1@remote.clifto.com> <5ff07$438f7ad6$4232bd6c$7468@COQUI.NET> Message-ID: <_jPjf.8429$wi2.4833@bignews1.bellsouth.net> Date: Thu, 01 Dec 2005 22:39:58 -0500 Bill wrote: > clifto wrote: > >> mcalhoun@ksu.edu wrote: >> >>> So I need to find an alternative way of getting my daily "fix"; >>> I sure hope someone has suggestion(s)! >> >> >> >> You can buy a super duper feed from Supernews. For less money, you can >> get a good feed (text only IIRC) from news.individual.net. >> >> Guess we're not in Kansas any more. >> > add teranews.com to the list teranews.com is ok, free (nominal one time setup charge) but they go up and down like a yo-yo. Article: 219714 of rec.radio.amateur.antenna From: "Joel Kolstad" Subject: Re: Radio Shack and my education Date: Thu, 1 Dec 2005 20:13:32 -0800 Message-ID: <11oviiu6q6u1m31@corp.supernews.com> References: <43865eea$0$32203$39cecf19@news.twtelecom.net> <11oek0b8to2mm42@corp.supernews.com> <0ZPhf.5587$wf.1166@newsread3.news.atl.earthlink.net> <11ofpe5kh28mk09@corp.supernews.com> Hi Roy, "Roy Lewallen" wrote in message news:11ofpe5kh28mk09@corp.supernews.com... > One of the reasons this is the only choice we have is that in times past, > there were stores which did pay the employees enough to get people who > understood the products. People would go in, get their questions answered, > then go to the Wal-Marts and Radio Shacks to buy the item because it was > cheaper there. What, have you been talking to the guys at HRO again at how people will come in and get technical advice for an hour and then go home and order on-line again or something? :-) Seriously, your point is well taken, although I'd suggest that all the product reviews you get from, e.g., Amazon.Com can actually be more useful than the information you'd get from a salesperson. There's no inherent bias (to want to sell you something), and you get to see comments from people with a wide range of background. (It's always kinda amusing to see people trash, say, some classical technical book when the real problem is that they're just not well enough educated yet to appreciate what they're reading!) Article: 219715 of rec.radio.amateur.antenna From: "Joel Kolstad" Subject: Re: Radio Shack and my education Date: Thu, 1 Dec 2005 20:19:59 -0800 Message-ID: <11oviv2b6n4i90@corp.supernews.com> References: <43865eea$0$32203$39cecf19@news.twtelecom.net> <11oek0b8to2mm42@corp.supernews.com> <0ZPhf.5587$wf.1166@newsread3.news.atl.earthlink.net> <11ofpe5kh28mk09@corp.supernews.com> <9b1io1hcv07plphfbppfdg5bc4nl4et4lp@4ax.com> "Richard Clark" wrote in message news:9b1io1hcv07plphfbppfdg5bc4nl4et4lp@4ax.com... > The social cost to America from Wal*Mart's business practices is on > the order of $1.5 Billion. I have a suspicion that, depending on whether you're pro- or anti-Wal*Mart, that number can easily more around by an order of magnitude... Presumably that $1.5B translates into higher taxes, right? The average person would rather pay $1 at WallyWorld and $0.25 in taxes rather than $1.10 at a different store... it's just human nature. And even if you convince the average person that their taxes are higher due to WallyWorld being around, most of them would just say to cut tax rates and hence reduce spending on whatever their favorite 'target' is -- the military for more liberally minded individuals, social programs for conservatives, etc. > When you look at if from the Chinese > perspective, they are getting gang-banged too. The presentation > showed how Wal*Mart paid workers 6¢ apiece for an item selling at $12. That strikes me as a red herring. For many products, there's very little relationship between the selling price and any one constituent cost involved in producing it, such as labor. (How much were the labor costs of the salesguy who sold you a one karat diamond ring for, say, $10,000, after all?) Article: 219716 of rec.radio.amateur.antenna From: "Joel Kolstad" Subject: Re: Radio Shack and my education Date: Thu, 1 Dec 2005 20:23:14 -0800 Message-ID: <11ovj54np9jc9c1@corp.supernews.com> References: <43866294$0$3756$39cecf19@news.twtelecom.net> "Korbin Dallas" wrote in message news:pan.2005.11.27.21.30.33.956522@null.org... > I have never understood this Bose thing, the speakers are some of the > worst ones on the market and they are flying out the doors all day long. 1) Many people like the sound of Bose. Regardless of how distorted that sound might be, the fact that people like it is most important. (And purposely distorting sound is very much the premise of many effects boxes used to produce music, after all!) 2) Bose does a good job of marketing their product as something that appeals to the 'hip' crowd, just like Apple has done with the iPod. > Its all marketing BS like the Wizbang cables to hook things up. Yep, but given that something like a stereo system is 100% a 'want' and not a 'need,' anything goes! I.e., no need for the government to regulate it, let people spend their excess cash on whatever they want... Article: 219717 of rec.radio.amateur.antenna From: "Asimov" Subject: Re: Antenna reception theory Message-ID: References: <26586-438F5A99-1152@storefull-3253.bay.webtv.net> Date: Fri, 02 Dec 2005 05:02:16 GMT "Richard Harrison" bravely wrote to "All" (01 Dec 05 14:18:33) --- on the heady topic of "Re: Antenna reception theory" RH> From: richardharrison@webtv.net (Richard Harrison) RH> Xref: core-easynews rec.radio.amateur.antenna:220709 RH> Roy Lewallen wrote: RH> "You can find the explanation for why this is in any electromagnetic RH> text." RH> I found it in Terman. [,,,] RH> From the above, it is seen that the electric field is not effective in RH> inducing current in a receiving antenna parallel to a wavefront. All RH> the energy intercepted by the antenna is induced by the magnetic field. That is outright false. Because I can very easily demonstrate detecting a static E-field by waving a sensitive probe across it. An antenna is just a stationary probe with a moving E-field. It is equivalent. Terman sucks. A*s*i*m*o*v ... Horse sense is the result of stable thinking. Article: 219718 of rec.radio.amateur.antenna Message-ID: <438FDA98.18A4361A@tori.com> From: Tori Subject: Re: OFF TOPIC, but how do y'all read these news groups? References: Date: Fri, 02 Dec 2005 05:24:42 GMT http://groups.google.com/ mcalhoun@ksu.edu wrote: > Note the multi-group posting. > > For 18 years, I've been reading newgroups on Unix (or Linux) machines, > first using "rn" (readnews) and later "nn" (netnews), but now my ISP > (Kansas State University) has notified me that, because their news server > is getting old and because I'm one of only a very few users, they are > dropping the service as of 28 December. > > So I need to find an alternative way of getting my daily "fix"; > I sure hope someone has suggestion(s)! > -- > --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: 219719 of rec.radio.amateur.antenna From: "W. Watson" Subject: Re: Antennas-History (What's Going On?) References: <7955-438B368C-194@storefull-3256.bay.webtv.net> Message-ID: Date: Fri, 02 Dec 2005 05:25:27 GMT Richard Clark wrote: > On Tue, 29 Nov 2005 04:28:22 GMT, "W. Watson" > wrote: > > >>A book by that title was not found on Amazon. You're not thinking of the >>latest edition of his "Antennas" are you? > > > Hi OM, > > Amazon is a poor start. Try a real book vendor: > http://www.alibris.com/search/search.cfm?qwork=349517&wtit=%22Antennas%20for%20All%20Applications&ptit=Antennas%20for%20All%20Applications&pauth=Kraus%2C%20John%20Daniel%2C%20and%20Leet%2C%20Kenneth%20J&pisbn=&pqty=3&pqtynew=3&pbest=84%2E18&pbestnew=84%2E18&matches=3&qsort=r&cm_re=works*listing*title > where there are three available. You may not like the price, however. > > 73's > Richard Clark, KB7QHC Yes, that is pretty steep. However, Kraus's 3rd edition of "Antennas" is $165. I'll be down in the SF Bay Area this weekend. Maybe I can find it at a library down there, or arrange to get an interlibrary loan. I use albris on occasion. Glad you reminded me of it. -- Wayne T. Watson (Watson Adventures, Prop., Nevada City, CA) (121.015 Deg. W, 39.262 Deg. N) GMT-8 hr std. time) Obz Site: 39° 15' 7" N, 121° 2' 32" W, 2700 feet Traveling in arid or desert country? Check your boots well to see if you have a scorpion in them. -- Survivorman, Discovery (SCI) Channel Web Page: Article: 219720 of rec.radio.amateur.antenna From: "W. Watson" Subject: Re: Antennas-History (What's Going On?) References: <7955-438B368C-194@storefull-3256.bay.webtv.net> Message-ID: Date: Fri, 02 Dec 2005 05:30:24 GMT Cecil Moore wrote: > Richard Clark wrote: > >> wrote: >> >>> A book by that title was not found on Amazon. You're not thinking of >>> the latest edition of his "Antennas" are you? > > > "for all applications" is part of a subtitle. > >> Amazon is a poor start. Try a real book vendor: >> http://www.alibris.com/search/search.cfm?qwork=349517&wtit=%22Antennas%20for%20All%20Applications&ptit=Antennas%20for%20All%20Applications&pauth=Kraus%2C%20John%20Daniel%2C%20and%20Leet%2C%20Kenneth%20J&pisbn=&pqty=3&pqtynew=3&pbest=84%2E18&pbestnew=84%2E18&matches=3&qsort=r&cm_re=works*listing*title >> >> where there are three available. You may not like the price, however. > > > Prices ($31) are good here: > http://dogbert.abebooks.com/servlet/SearchResults?y=11&isbn=0072321032&x=44 Interesting. It's in San Jose. I'll be there Saturday. I wonder where they are? (Cheapestbooks). Interesting source. When I was a student (a very long time ago), I would sometimes buy paperback books of many texts from Blackwells in England. The price was usually about 1/2. Sometimes (back then, and maybe still), one could by tech books from China that was on almost tissue paper pages. They were quite cheap. -- Wayne T. Watson (Watson Adventures, Prop., Nevada City, CA) (121.015 Deg. W, 39.262 Deg. N) GMT-8 hr std. time) Obz Site: 39° 15' 7" N, 121° 2' 32" W, 2700 feet Traveling in arid or desert country? Check your boots well to see if you have a scorpion in them. -- Survivorman, Discovery (SCI) Channel Web Page: Article: 219721 of rec.radio.amateur.antenna From: "GeWaz" Subject: RAIC Industry Traps Date: Fri, 2 Dec 2005 12:20:15 +0000 (UTC) Message-ID: This is a multi-part message in MIME format. ------=_NextPart_000_006B_01C5F73A.B953D510 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Hi, I have a pair or RAIC Industry Traps. Model L-80. Does anyone have = any info on these or where info can be obtained? Thank ------=_NextPart_000_006B_01C5F73A.B953D510 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
Hi, I have a pair or RAIC Industry = Traps. Model=20 L-80. Does anyone have any info on these or where info can be=20 obtained?
Thank
------=_NextPart_000_006B_01C5F73A.B953D510-- Article: 219722 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Antennas-History (What's Going On?) References: <7955-438B368C-194@storefull-3256.bay.webtv.net> Message-ID: Date: Fri, 02 Dec 2005 13:58:52 GMT W. Watson wrote: > When I was a student (a very long time ago), I would sometimes buy > paperback books of many texts from Blackwells in England. The price was > usually about 1/2. Sometimes (back then, and maybe still), one could by > tech books from China that was on almost tissue paper pages. They were > quite cheap. Here's another good book, "Optics", by Eugene Hecht, for $24, containing the best treatment of superposition and interference that I have ever seen. http://dogbert.abebooks.com/servlet/SearchResults?y=9&isbn=0805385665&x=46 -- 73, Cecil http://www.qsl.net/w5dxp Article: 219723 of rec.radio.amateur.antenna From: Eskay Subject: Re: Ground-Level HF Beam Tuning? References: <1133454210.047291.209170@g44g2000cwa.googlegroups.com> Message-ID: <1j1jnzen4s3yz.ipv0cukgl67m$.dlg@40tude.net> Date: Fri, 02 Dec 2005 14:57:43 GMT On Thu, 01 Dec 2005 17:19:04 GMT, kd5sak wrote: > "Brian Kelly" wrote in message > news:1133454210.047291.209170@g44g2000cwa.googlegroups.com... >> I'm mulling the design/homebrewing of a hexagonal 20/17/15/12/10M wire >> beam a la the Traffie Hexbeam. The problem with just about all projects >> like this is the number of up/down iterations required to tweak the >> tuning of the things. Put it up, calculate the required changes in >> element lengths, take it down, make the adjustments, put it back up to >> check it again, pull it down and go thru the whole cycle ad nauseam. >> Pain in the tush. >> >> I've seen suggestions here and there about simply aiming a beam >> vertically upward and doing all the tuning at ground level instead. >> Which would save an awful lot of time and effort. If it works. Does >> anybody around here have any experience with this method and if so how >> succesful was it? >> >> Thanks, >> >> Brian w3rv >> > > Another local Ham and I have built two monoband 20 meter versions of the > HexBeam > utilizing info from W1GQLs hexbeam website (one with PVC spreaders and one > with fiberglass rod spreaders). Neither had to be adjusted at all after the > original wire length was cut. Mine has usable tuning at just above ground > level and it's expected to get only better with height, as the other one > did. Granted, we didn't have the other band elements to fuss with. If you > can get element lengths and vertical separation distances from someone with > a working multibander chances are you won't need to do any adjusting on > those, either. W1GQL has suggested, with the finite lifespan of such > antennas and the current lowpoint of the sunspot cycle, that there is no > overwhelming need for 10, 12, and 15 meter elements for at least the next > couple of years. You might try building your antenna as a monoband 20 meter, > but construct the antenna with sufficient spreader tension and bow depth > that you can later add additional bands. The foregoing advice is free and > not necessarily valuable, but is given with friendly intent.(G) My own > fiberglass HexBeam has a 30" bow depth and I may yet attempt to add a band > or two later. Good luck with yours however you choose to build it. > > Harold > KD5SAK You could also join the Yahoo newsgroup that is devoted to the Hexbeam. There is an awfull lot of info in the archives there including photos. Eskay. Article: 219724 of rec.radio.amateur.antenna From: richardharrison@webtv.net (Richard Harrison) Subject: Re: Antenna reception theory Date: Fri, 2 Dec 2005 10:15:18 -0600 Message-ID: <7955-43907316-416@storefull-3256.bay.webtv.net> References: Asimov wrote: "Terman sucks." Termn`s writings have been exposed for anyone to criticize for most of a century. His 1955 edition has been out there for 50 years. No retractions or corrections are necessary. Detection of static E-fields is not relevant. Charles Coulomb in 1785 showed electric charges exert forces on each other that are inversely proportional to the square of the distance between them. This was the birth of the "inverse square law" as Coulomb`s discovery applies to magnetic attraction and repulsion, too. In an electromagnetic field, propagation depends upon the electric field begetting a magnetic field and vice versa. On average, each field contains 50% of the total energy. The electromagnetic field of an antenna could be calculated from the distribution of voltage on the conductors. Problem is voltmeter leads would be in the r-f field and this would tend to make measured voltages inaccurate. R-F current is conveniently and accurately measured with a thermocouple ammeter. Strength of an electromagnetic wave is usually measured and quoted in terms of its electric field in volts per meter. This is the number of volts which would be induced in a one-meter length of wire placed in the field parallel to the electric lines of force. Volts in the wire are produced by movement of magnetic flux across the wire. Best regards, Richard Harrison, KB5WZI Article: 219725 of rec.radio.amateur.antenna From: nospam@nouce.bellatlantic.net Subject: Re: Ground-Level HF Beam Tuning? Message-ID: <87u0p1d8m9bkrp8c8ogtmmqfafumiq46vb@4ax.com> References: <1133454210.047291.209170@g44g2000cwa.googlegroups.com> <1133509122.697246.45140@g49g2000cwa.googlegroups.com> Date: Fri, 02 Dec 2005 16:43:16 GMT On 1 Dec 2005 23:38:42 -0800, "Brian Kelly" wrote: > >nospam@nouce.bellatlantic.net wrote: >> On 1 Dec 2005 08:23:30 -0800, "Brian Kelly" wrote: >> > >. . . . > >> >I've seen suggestions here and there about simply aiming a beam >> >vertically upward and doing all the tuning at ground level instead. >> >Which would save an awful lot of time and effort. If it works. Does >> >anybody around here have any experience with this method and if so how >> >succesful was it? >> > >> >Thanks, >> > >> >Brian w3rv >> >> It will get you close. > >. . . Good. Beats having to taking the beam down and putting it back up >several times just to get in the ballpark. I expect to have to do a >couple of these final tweaking cycles after rough tuning at ground >level. Would be a *big* help. > >> However it really depends on the front to >> back of the antenna. Dipoles do poorly this way, 2 element beams >> slightly better. I've done 3 element 6m beams with the reflector only >> 4ft off the ground pointing up with excellent success. Seems the >> breakpoint is some where around better than 10or 12 DB F/B ratio. > >Per my response to W4ZCV hexagonal beams typically have 10-20 dB F/B >ratios so they're in range of your "breakpoint". > >> You do need distance from the ground or it acts like a reflector >> and messes with your measurments. > >Understood. Looks like you and W4ZCV are basically in agreement so I'll >follow you two in this direction. > >Thanks! The yabut/gotcha is until the beam is acting like one you don't have the F/B ratio to rely on so it may take an iteration or two before you converge. Once you are in the fine tuning range it should work well pointing it up. This is a problem that most Yagis don't have as tuning is limited to tweeking the match for the driver and maybe the driven element length to make the match work right. So what regular yagis are tuned up pointing up they are really just having the match set up correctly(usually). Allison Article: 219726 of rec.radio.amateur.antenna From: Allodoxaphobia Subject: Re: OFF TOPIC, but how do y'all read these news groups? Date: 2 Dec 2005 17:02:34 GMT Message-ID: References: On Fri, 02 Dec 2005 12:39:23 +0000, Highland Ham wrote: > You can access newsgroups via Google ,but I believe you then need a > gmail e-mail address ,which is free anyway. > > Frank GM0CSZ / KN6WH > >====================mcalhoun@ksu.edu wrote:==================== > >> Note the multi-group posting. >> >> For 18 years, I've been reading newgroups on Unix (or Linux) machines, >> first using "rn" (readnews) and later "nn" (netnews), but now my ISP >> (Kansas State University) has notified me that, because their news server >> is getting old and because I'm one of only a very few users, they are >> dropping the service as of 28 December. >> >> So I need to find an alternative way of getting my daily "fix"; >> I sure hope someone has suggestion(s)! And, using Google, you run the risk of being killfiled by a Great Many usenet denizens because of the gawd-awful defaults Google uses for follow-ups in its posting configuration. But, then, you knew that... So, you being a *nix user, I can't see you getting excited about doing usenet 'text work' with a bloated cartoon interface. I'm a *nix user, too, and I can recommend Individual.net ( http://news.individual.net/ ). It's is the follow-on/re-incarnation of the free news.cis.dfn.de. It costs 10 Euro per year and it's well worth it. I used the online sign-up and paid via the FirstgGate ( http://firstgate.com/EU/en/info.html ) service they use. Now, if only slrn could score on top-posters. sigh... HTH Jonesy -- Marvin L Jones | jonz | W3DHJ | linux Pueblo, Colorado | @ | Jonesy | OS/2 __ 38.24N 104.55W | config.com | DM78rf | SK Article: 219727 of rec.radio.amateur.antenna From: Allodoxaphobia Subject: Re: Free Catalog: Coax Cable, Connectors & Adapters Date: 2 Dec 2005 17:08:02 GMT Message-ID: References: On Thu, 1 Dec 2005 10:08:27 -0800, AAA RF Products wrote: > For your free copy of our new catalog, Limit detector tripped! *plonk* Article: 219728 of rec.radio.amateur.antenna From: "Kathy Lee" Subject: hi im crisco kathy Message-ID: <1133548250.70ba59deb172bfa745d5dd0a96cdfbe1@fe5.teranews.com> Date: Fri, 02 Dec 2005 18:30:50 +0000 I AM CRISCO KATHY,TAX SEASON IS ALMOST UPON US. I CAN GET YOU THE BEST RETURN. IT MIGHT BE A LITTLE BIT ILLEGAL.BUT WHAT THE HECK,THE GOVERMENT TAKES TO MUCH OF OUR MONEY. BE SURE AND BRING A BIG CAN OF CRISCO WITH YOU. I WORK BEST ON MY KNEES WHILE SOMEONE SLATHERS MY FAT ASS WITH CRISCO. BRING A BIG CAN, I HAVE A VERY LARGE ASS. Article: 219729 of rec.radio.amateur.antenna From: Jim Kelley Subject: Re: Antenna reception theory Date: Fri, 02 Dec 2005 11:17:51 -0800 Message-ID: References: <26586-438F5A99-1152@storefull-3253.bay.webtv.net> Asimov wrote: > "Richard Harrison" bravely wrote to "All" (01 Dec 05 14:18:33) > --- on the heady topic of "Re: Antenna reception theory" > > RH> From: richardharrison@webtv.net (Richard Harrison) > RH> Xref: core-easynews rec.radio.amateur.antenna:220709 > > RH> Roy Lewallen wrote: > RH> "You can find the explanation for why this is in any electromagnetic > RH> text." > > RH> I found it in Terman. > [,,,] > RH> From the above, it is seen that the electric field is not effective in > RH> inducing current in a receiving antenna parallel to a wavefront. All > RH> the energy intercepted by the antenna is induced by the magnetic field. > > > That is outright false. Because I can very easily demonstrate > detecting a static E-field by waving a sensitive probe across it. > An antenna is just a stationary probe with a moving E-field. It is > equivalent. Consider the direction the E field is moving and which direction any electrostatically induced current might flow. Then apply the same criteria to a magnetic field. A*C*6*X*G Terman sucks. > > A*s*i*m*o*v > > ... Horse sense is the result of stable thinking. > Article: 219730 of rec.radio.amateur.antenna From: "Chuck" Subject: Re: hi im crisco kathy Date: Fri, 2 Dec 2005 16:25:21 -0600 Message-ID: <11p1ieinc6dj38e@corp.supernews.com> References: <1133548250.70ba59deb172bfa745d5dd0a96cdfbe1@fe5.teranews.com> Doug says I should stop by and you could get me lots of money back if I bring some crisco. But all I have is canola oil as I am on a heart healthy diet and eating that much crisco out of your snatch would surely cause a clogged artery. "Kathy Lee" wrote in message news:1133548250.70ba59deb172bfa745d5dd0a96cdfbe1@fe5.teranews.com... >I AM CRISCO KATHY,TAX SEASON IS ALMOST UPON US. I > CAN GET YOU THE BEST > RETURN. IT MIGHT BE A LITTLE BIT ILLEGAL.BUT WHAT > THE HECK,THE > GOVERMENT TAKES TO MUCH OF OUR MONEY. BE SURE AND > BRING A BIG CAN OF > CRISCO WITH YOU. I WORK BEST ON MY KNEES WHILE > SOMEONE SLATHERS MY FAT > ASS WITH CRISCO. BRING A BIG CAN, I HAVE A VERY > LARGE ASS. > > > Article: 219731 of rec.radio.amateur.antenna From: Jack O'Neill Subject: Re: hi im crisco kathy References: <1133548250.70ba59deb172bfa745d5dd0a96cdfbe1@fe5.teranews.com> <11p1ieinc6dj38e@corp.supernews.com> Message-ID: Date: Fri, 02 Dec 2005 18:20:55 -0500 This is a multi-part message in MIME format. --------------090507030808090708080704 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit jezzzzzzzz Chuck wrote: >Doug says I should stop by and you could get me lots of money back if I >bring some crisco. But all I have is canola oil as I am on a heart healthy >diet and eating that much crisco out of your snatch would surely cause a >clogged artery. > >"Kathy Lee" wrote in message >news:1133548250.70ba59deb172bfa745d5dd0a96cdfbe1@fe5.teranews.com... > > >>I AM CRISCO KATHY,TAX SEASON IS ALMOST UPON US. I >>CAN GET YOU THE BEST >>RETURN. IT MIGHT BE A LITTLE BIT ILLEGAL.BUT WHAT >>THE HECK,THE >>GOVERMENT TAKES TO MUCH OF OUR MONEY. BE SURE AND >>BRING A BIG CAN OF >>CRISCO WITH YOU. I WORK BEST ON MY KNEES WHILE >>SOMEONE SLATHERS MY FAT >>ASS WITH CRISCO. BRING A BIG CAN, I HAVE A VERY >>LARGE ASS. >> >> >> >> >> > > > > --------------090507030808090708080704 Content-Type: text/html; charset=us-ascii Content-Transfer-Encoding: 7bit jezzzzzzzz


Chuck wrote:
Doug says I should stop by and you could get me lots of money back if I 
bring some crisco. But all I have is canola oil as I am on a heart healthy 
diet and eating that much crisco out of your snatch would surely cause a 
clogged artery.

"Kathy Lee" <KC8QJP@yahoo.net> wrote in message 
news:1133548250.70ba59deb172bfa745d5dd0a96cdfbe1@fe5.teranews.com...
  
I AM CRISCO KATHY,TAX SEASON IS ALMOST UPON US. I
CAN GET YOU THE BEST
RETURN. IT MIGHT BE A LITTLE BIT ILLEGAL.BUT WHAT
THE HECK,THE
GOVERMENT TAKES TO MUCH OF OUR MONEY. BE SURE AND
BRING A BIG CAN OF
CRISCO WITH YOU. I WORK BEST ON MY KNEES WHILE
SOMEONE SLATHERS MY FAT
ASS WITH CRISCO. BRING A BIG CAN, I HAVE A VERY
LARGE ASS.

--------------090507030808090708080704-- Article: 219732 of rec.radio.amateur.antenna From: "Fred W4JLE" References: <1133576906.890685.201870@g47g2000cwa.googlegroups.com> Subject: Re: My vertical blew down!!! Date: Fri, 2 Dec 2005 22:24:48 -0500 Message-ID: <9cffe$43911003$97d56a33$7851@ALLTEL.NET> It begs the question, what was it made of? It must have been very thin metal to blow apart only 16 feet, guyed by ropes. Please enlighten us. wrote in message news:1133576906.890685.201870@g47g2000cwa.googlegroups.com... > Hi, > > It seems that my location boasts 60 to 110 mph winds on a regular > basis. I had put up a 1/4 wavelength 20m vertical with 1/8 wavelength > radials elevated at 7 feet, with rope guys... and the wind blew it > apart like so much tin foil! > > Does anyone know of a decent commercial design for less than $1000 for > a free standing 30 to 40 foot support that can take this darn wind??? > > Thanks, > > The Eternal Squire > Article: 219733 of rec.radio.amateur.antenna From: "Asimov" Subject: Re: Antenna reception theory Message-ID: References: Date: Sat, 03 Dec 2005 05:11:05 GMT "Jim Kelley" bravely wrote to "All" (02 Dec 05 11:17:51) --- on the heady topic of "Re: Antenna reception theory" JK> From: Jim Kelley JK> Xref: core-easynews rec.radio.amateur.antenna:220745 JK> Asimov wrote: > "Richard Harrison" bravely wrote to "All" (01 Dec 05 14:18:33) > --- on the heady topic of "Re: Antenna reception theory" > > RH> From: richardharrison@webtv.net (Richard Harrison) > RH> Xref: core-easynews rec.radio.amateur.antenna:220709 > > RH> Roy Lewallen wrote: > RH> "You can find the explanation for why this is in any electromagnetic > RH> text." > > RH> I found it in Terman. > [,,,] > RH> From the above, it is seen that the electric field is not effective in > RH> inducing current in a receiving antenna parallel to a wavefront. All > RH> the energy intercepted by the antenna is induced by the magnetic field. > > > That is outright false. Because I can very easily demonstrate > detecting a static E-field by waving a sensitive probe across it. > An antenna is just a stationary probe with a moving E-field. It is > equivalent. JK> Consider the direction the E field is moving and which direction any JK> electrostatically induced current might flow. Then apply the same JK> criteria to a magnetic field. JK> A*C*6*X*G JK> Terman sucks. I regret having written that Terman sucks. However, I'm reminded that there is a lot of stuff missing in the 1955 edition of Encyclopedia Britanica up in the attic. Clearly I don't say the EB sucks either, so a 1955 book on electromagentic wave theory might be missing a few things as well. Unless you believe everything that there ever is to learn about EM is that 1955 book. But it is wrong to state that the magnetic field alone is responsible for the interception of wave energy in a metallic conductor. A*s*i*m*o*v ... Isaac Asimov : 1920-1992 : Gone to the stars! Article: 219734 of rec.radio.amateur.antenna From: Roy Lewallen Subject: Re: how to model frequency response of a loaded vertical ? Date: Fri, 02 Dec 2005 21:58:54 -0800 Message-ID: <11p2d12qnuu0m52@corp.supernews.com> References: dansawyeror wrote: > All, > > I am creating a 'scaled' model of a loaded vertical. The model is > complete and in place. However I immediately realized I had no idea of > the 'theoretical' response. How can I calculate the expected impedance > response of a loaded vertical? It a mid load construction, > > the base in #10 solid copper 4 inchs, > the coil is .6 pitch, 1 inch diameter, 5 turns #12, measuring .72 uH, > and the top is 4 inch #12. > > The antenna appears to resonate at about 112 MHz. > > The instrumentation, a directional coupler measuring reflection is > located at the base, directly under the 'ground plane'. This allows > measuring input and reflected signal strength. > > The question is: How can I plot the expected impedance from say 100 MHz > to 130 MHz? > > Thanks - Dan The free EZNEC demo from http://eznec.com will give you the information you need. Roy Lewallen, W7EL Article: 219735 of rec.radio.amateur.antenna From: "Falky foo" References: <1133576906.890685.201870@g47g2000cwa.googlegroups.com> <9cffe$43911003$97d56a33$7851@ALLTEL.NET> <1133584284.471704.259160@g49g2000cwa.googlegroups.com> Subject: Re: My vertical blew down!!! Message-ID: Date: Sat, 03 Dec 2005 06:02:50 GMT dude it's 60-100 mph wind! You're gonna have to shell out bucks to make anything that can stand up to that for any length of time. Article: 219736 of rec.radio.amateur.antenna From: "Lee" References: <1133576906.890685.201870@g47g2000cwa.googlegroups.com> Subject: Re: My vertical blew down!!! Message-ID: Date: Sat, 03 Dec 2005 06:34:55 GMT wrote in message news:1133576906.890685.201870@g47g2000cwa.googlegroups.com... > Hi, > > It seems that my location boasts 60 to 110 mph winds on a regular > basis. I had put up a 1/4 wavelength 20m vertical with 1/8 wavelength > radials elevated at 7 feet, with rope guys... and the wind blew it > apart like so much tin foil! > > Does anyone know of a decent commercial design for less than $1000 for > a free standing 30 to 40 foot support that can take this darn wind??? > > Thanks, > > The Eternal Squire > I use a fishing rod with a wire centre conductor for 40 metres band (33`without guys), with a 5` mounting pole buried in the ground ....you ought to see that mother bend ...... hasn`t fallen or blown down yet!!! ;-) Lee.......G6ZSG..... Article: 219737 of rec.radio.amateur.antenna From: Chris W <1qazse4@cox.net> Subject: bidirectional 440 yagi antenna Message-ID: Date: Sat, 03 Dec 2005 01:06:53 -0600 Does anyone know of a good design for a reasonably high gain bidirectional antenna for a 440mhz video TX? I am putting a 4 watt A/V TX in an RC plane that will fly on auto pilot directly away from the RX, make a 180 degree turn and fly directly back. So to get the best range I was thinking some kind of bidirectional yagi. Depending on element spacing and how big of a plane I get, I can probably only have 3 elements maybe 5. -- Chris W KE5GIX Gift Giving Made Easy Get the gifts you want & give the gifts they want One stop wish list for any gift, >from anywhere, for any occasion! http://thewishzone.com Article: 219738 of rec.radio.amateur.antenna From: Stananger <********@***.***> Subject: Re: My vertical blew down!!! References: <1133576906.890685.201870@g47g2000cwa.googlegroups.com> Message-ID: Date: Sat, 03 Dec 2005 07:47:50 GMT eternalsquire@comcast.net wrote: > Hi, > > It seems that my location boasts 60 to 110 mph winds on a regular > basis. I had put up a 1/4 wavelength 20m vertical with 1/8 wavelength > radials elevated at 7 feet, with rope guys... and the wind blew it > apart like so much tin foil! > > Does anyone know of a decent commercial design for less than $1000 for > a free standing 30 to 40 foot support that can take this darn wind??? > > Thanks, > > The Eternal Squire Maybe you should move! Stan AH6JR Article: 219739 of rec.radio.amateur.antenna From: "Henry Kiefer" References: Subject: Re: OFF TOPIC, but how do y'all read these news groups? Date: Sat, 3 Dec 2005 12:25:41 +0100 Message-ID: <439182de$0$20842$9b4e6d93@newsread2.arcor-online.net> I used news.cis.dfn.de a while but changed to arcor-news later because of the now charging at news.cis.dfn.de Arcor is still free and fast, no reliable problems. You must have a Arcor login but this is even a free mail-account. If you like I can you send instructions where. I don't know it just if the head. Maybe they filter not-german clients out via your IP-address. But why not give it a try? Sent via Arcor - Henry > So, you being a *nix user, I can't see you getting excited about doing > usenet 'text work' with a bloated cartoon interface. I'm a *nix user, > too, and I can recommend Individual.net ( http://news.individual.net/ ). > It's is the follow-on/re-incarnation of the free news.cis.dfn.de. It > costs 10 Euro per year and it's well worth it. I used the online sign-up > and paid via the FirstgGate ( http://firstgate.com/EU/en/info.html ) > service they use. > > Now, if only slrn could score on top-posters. sigh... > > HTH > Jonesy > -- > Marvin L Jones | jonz | W3DHJ | linux > Pueblo, Colorado | @ | Jonesy | OS/2 __ > 38.24N 104.55W | config.com | DM78rf | SK Article: 219740 of rec.radio.amateur.antenna From: Roy Lewallen Subject: Re: Antenna reception theory Date: Sat, 03 Dec 2005 03:58:06 -0800 Message-ID: <11p322i7mfa917d@corp.supernews.com> References: <7955-43907316-416@storefull-3256.bay.webtv.net> Richard Harrison wrote: > . . . > Strength of an electromagnetic wave is usually measured and quoted in > terms of its electric field in volts per meter. This is the number of > volts which would be induced in a one-meter length of wire placed in the > field parallel to the electric lines of force. . . If the wavelength is >> 1 m, the voltage induced in the center of an open-circuited 1 m diple by a 1 V/m field is 0.5 volt, not 1 volt. Roy Lewallen, W7EL Article: 219741 of rec.radio.amateur.antenna From: "Reg Edwards" Subject: Re: Antenna reception theory Date: Sat, 3 Dec 2005 13:22:05 +0000 (UTC) Message-ID: References: <7955-43907316-416@storefull-3256.bay.webtv.net> <11p322i7mfa917d@corp.supernews.com> Roy, What is the voltage measured between the bottom-end of a 1 metre vertical antenna and a perfect ground when the field strength is 1 V/m and the wavelength is >> 1 m. ---- Reg. Article: 219742 of rec.radio.amateur.antenna From: John Ferrell Subject: Re: bidirectional 440 yagi antenna Message-ID: References: Date: Sat, 03 Dec 2005 15:04:01 GMT A simple dipole will do what you want. That is a lot of power in the airborne TX. 400 mw is still over kill and 40 mw will probably do the job. At some point you will need to regain control with conventional RC equipment and getting a signal into the airplane with that much radiated power may not be easy. If you are short on the RC airplane experience I suggest you consider a Telemaster from Hobby Lobby. Smaller versions are available for experience and the Senior (8 foot span) with carry many pounds of pay load. What you are considering is called an RPV and is a hot item in military use now days. John Ferrell W8CCW On Sat, 03 Dec 2005 01:06:53 -0600, Chris W <1qazse4@cox.net> wrote: >Does anyone know of a good design for a reasonably high gain >bidirectional antenna for a 440mhz video TX? I am putting a 4 watt A/V >TX in an RC plane that will fly on auto pilot directly away from the RX, >make a 180 degree turn and fly directly back. So to get the best range >I was thinking some kind of bidirectional yagi. Depending on element >spacing and how big of a plane I get, I can probably only have 3 >elements maybe 5. John Ferrell W8CCW Article: 219743 of rec.radio.amateur.antenna From: "Reg Edwards" Subject: Re: My vertical blew down!!! Date: Sat, 3 Dec 2005 15:28:39 +0000 (UTC) Message-ID: References: <1133576906.890685.201870@g47g2000cwa.googlegroups.com> Actually, pure aluminium is even softer and far more ductile than copper and is useless as a construction material. But some grades of copper/aluminium alloy, known in the UK as Duraluminum or just Dural, have properties approaching carbon steel and are corrosion resistant. Light in weight. Easily machined and extruded. Maintain a good appearance. High electrical conductivity. More expensive than steel. They are used, for example, for ladders and scaffold poles. When used for tubular rigid dipoles and antenna masts they collapse under high winds only because the wall thickness is too thin. Commonly used for radio chassis and sheet metal roofs. But NOT pure aluminium, just a few percent of copper. ---- Reg. "Cecil Moore" wrote in message news:vJgkf.26163$7h7.13379@newssvr21.news.prodigy.com... > eternalsquire@comcast.net wrote: > > It seems that my location boasts 60 to 110 mph winds on a regular > > basis. I had put up a 1/4 wavelength 20m vertical with 1/8 wavelength > > radials elevated at 7 feet, with rope guys... and the wind blew it > > apart like so much tin foil! > > I use 2x(2"x4"s) fastened together for a 4"x4" support and 1/4WL > wire radials as ground-plane/guy-wires. The vertical section is > assembled from 6' telescoping aluminum sections following the beam > element design guidelines in the ARRL Antenna Book. The top 8.5' > is a stainless steel CB whip. It has withstood wind gusts of about > 100 mph. As others have said, copper is a poor choice for a 20m > vertical. > -- > 73, Cecil http://www.qsl.net/w5dxp Article: 219744 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: My vertical blew down!!! References: <1133576906.890685.201870@g47g2000cwa.googlegroups.com> Message-ID: Date: Sat, 03 Dec 2005 15:50:30 GMT Reg Edwards wrote: > But NOT pure aluminium, just a few percent of copper. Next time I'll have to remember what a purist you are, Reg. I'll specify Aluminum 6063-T832 or some such. -- 73, Cecil http://www.qsl.net/w5dxp Article: 219745 of rec.radio.amateur.antenna From: Jim Higgins Subject: Re: My vertical blew down!!! Message-ID: References: <1133576906.890685.201870@g47g2000cwa.googlegroups.com> <9cffe$43911003$97d56a33$7851@ALLTEL.NET> <1133584284.471704.259160@g49g2000cwa.googlegroups.com> Date: Sat, 03 Dec 2005 15:56:17 GMT On 2 Dec 2005 20:31:24 -0800, eternalsquire@comcast.net wrote: >Ground system: > >5 foot of 1 inch diameter galvanized iron pipe, halfway stuck in ground >with concrete. >1 inch diameter galvanized coupler >5 foot of 1 inch diameter galvanized pipe >1 inch to 3/4 inch copper reducer >1 foot of 3/4 inch copper pipe >4 tees: 3/4 inch thru vs 1/2 inch out, soldered lengthwise along >copper pipe. >an 8 foot length of 1/2 inch copper pipe soldered into each tee >tees are reinforced above and below radials with a hose clamp >coax shield connected to top of copper pipe > >Radiator: >10 feet of 3/4 inch diameter copper pipe >9 foot carbon fiber fishing rod, handle epoxied and inserted into pipe >a wire is attached to copper pipe and run up to end of rod. >Hot end of coax connected to bottom of copper pipe > >Ground system and Radiator are connected in-line with a PVC twist shaft >coupler designed for 3/4 inch pipe, weather sealed with epoxy. A gap >of 1 inch between pipes inside the coupler is filled with styrofoam to >prevent contact. > >Rope guys are econnected to the top part of the shaft coupler, as the >middle of the shaft coupler is predicted to be weakest point. > >Sure enough, a continuous wind in excess of 60 mph vibrated the shaft >coupler into 2 pieces despite the guys, the radiator then collided with >a radial, knocking a radial out of alignment and ripping apart a hose >clamp. I suspect the wind is going to finish the job overnight. > >Sigh, > >The Eternal Squire Iron pipe is brittle. You need to use steel. Given your situation, I'd suggest schedule 80 pipe. Even if you use steel, the threads at the couplers represent stress points and are much weaker when it comes to resisting bending moments than the straight pipe sections. That coupler less than 5 feet above the ground is probably OK, but the rest should be nonthreaded and welded or brazed to nonthreaded pipe. For God's sake, don't attach the guys at the coupler unless you also attach a set of guys well above the coupler... otherwise you're just asking for a break at the already weaker coupler. Where do you live that you regularly experience Category 2 (actually Cat 2 on the border of being Cat 3) winds? Article: 219746 of rec.radio.amateur.antenna From: "Denton" Subject: Re: My vertical blew down!!! Date: Sat, 3 Dec 2005 08:38:30 -0800 Message-ID: <11p3ig9jra7ppf4@corp.supernews.com> References: <1133576906.890685.201870@g47g2000cwa.googlegroups.com> Visit a farm supply house and see what they have for aluminum tubing...the stuff they use for making racks for trucks and pickups. wrote in message news:1133576906.890685.201870@g47g2000cwa.googlegroups.com... > Hi, > > It seems that my location boasts 60 to 110 mph winds on a regular > basis. I had put up a 1/4 wavelength 20m vertical with 1/8 wavelength > radials elevated at 7 feet, with rope guys... and the wind blew it > apart like so much tin foil! > > Does anyone know of a decent commercial design for less than $1000 for > a free standing 30 to 40 foot support that can take this darn wind??? > > Thanks, > > The Eternal Squire > Article: 219747 of rec.radio.amateur.antenna From: Paul Burridge Subject: Short coax interconnections - phase implications?? Date: Sat, 03 Dec 2005 16:52:30 +0100 Message-ID: Hello guys, I recently picked up an old vector network analyser in working order but minus the 3 interconnects between it and the transmission/reflection bridge. These are specified in the manual to be exactly 24" long, 50 ohms and terminated by N-type plugs. I've been told the length of these patch leads is quite critical to getting accurate measurements with this VNA, but am at a loss to work out why 24" is specified when the frequency range of this device is 4Mhz to 1300Mhz. If it were only capable of measuring at one fixed frequency, I could understand the need for a specifically cut length of some fraction of a wavelength. Can anyone explain the relevance of 24" in this context? Also, will *any* 50 ohm coax suffice for this purpose or has it got to be something special? Thanks, P. -- "What is now proved was once only imagin'd" - William Blake Article: 219748 of rec.radio.amateur.antenna From: Al Subject: Re: OFF TOPIC, but how do y'all read these news groups? References: <439182de$0$20842$9b4e6d93@newsread2.arcor-online.net> Message-ID: Date: Sat, 03 Dec 2005 16:58:23 GMT In article <439182de$0$20842$9b4e6d93@newsread2.arcor-online.net>, "Henry Kiefer" wrote: > I used news.cis.dfn.de a while but changed to arcor-news later because of > the now charging at news.cis.dfn.de > Arcor is still free and fast, no reliable problems. You must have a Arcor > login but this is even a free mail-account. If you like I can you send > instructions where. I don't know it just if the head. > Maybe they filter not-german clients out via your IP-address. But why not > give it a try? > > Sent via Arcor - > Henry > > > > So, you being a *nix user, I can't see you getting excited about doing > > usenet 'text work' with a bloated cartoon interface. I'm a *nix user, > > too, and I can recommend Individual.net ( http://news.individual.net/ ). > > It's is the follow-on/re-incarnation of the free news.cis.dfn.de. It > > costs 10 Euro per year and it's well worth it. I used the online sign-up > > and paid via the FirstgGate ( http://firstgate.com/EU/en/info.html ) > > service they use. > > > > Now, if only slrn could score on top-posters. sigh... > > > > HTH > > Jonesy > > -- > > Marvin L Jones | jonz | W3DHJ | linux > > Pueblo, Colorado | @ | Jonesy | OS/2 __ > > 38.24N 104.55W | config.com | DM78rf | SK > > I have used the Google newsgroups on occasion. All you need is a browser. I don't care for the interface though. Al Article: 219749 of rec.radio.amateur.antenna From: Chris W <1qazse4@cox.net> Subject: Re: bidirectional 440 yagi antenna References: Message-ID: Date: Sat, 03 Dec 2005 11:00:06 -0600 John Ferrell wrote: >A simple dipole will do what you want. That is a lot of power in the >airborne TX. 400 mw is still over kill and 40 mw will probably do the >job. At some point you will need to regain control with conventional >RC equipment and getting a signal into the airplane with that much >radiated power may not be easy. > >If you are short on the RC airplane experience I suggest you consider >a Telemaster from Hobby Lobby. Smaller versions are available for >experience and the Senior (8 foot span) with carry many pounds of pay >load. > > I guess you didn't notice the part about an autopilot, I plan on having the plane fly out about 10 or 15 miles out and then back, not just where I can see it. I have several years and a few hundred hours experience flying RC planes but still plan on using a plane that is reasonably easy to fly so the autopilot has an easier time controlling it. I have a few tests I plan to do to check if the video TX will cause a problem with the RC RX. I will rig up a servo to turn the video TX on and off and will set a fail safe so that if the RC RX can't get it's signal it will shut off the video TX. I will first set the video TX to very low power (the TX I am looking at is adjustable from 0 to 4+ watts), then I will make sure my video shut off switch is working good then make small increases in the video TX power and see how far away I can fly the plane before the fail safe shuts down the video TX. If the high power video TX does prevent me from retaking control of the plane from the autopilot/GPS navigation system, I have a plan B that I am working on. A system that will make adjustments in video TX output power at various way points, so it adjusts the power up as it gets farther away, and back down as it gets closer, this will have the added benefit of increasing the life of my video TX battery. I'm not sure how I will do that yet but I have a few ideas I am looking into. -- Chris W KE5GIX Gift Giving Made Easy Get the gifts you want & give the gifts they want One stop wish list for any gift, >from anywhere, for any occasion! http://thewishzone.com Article: 219750 of rec.radio.amateur.antenna From: Paul Burridge Subject: Short coax interconnections - phase implications?? Date: Sat, 03 Dec 2005 17:19:29 +0100 Message-ID: <1bh3p11kcftnc9rtrhfihqc7r2olhe2oqj@4ax.com> Hello guys, I recently picked up an old vector network analyser in working order but minus the 3 interconnects between it and the transmission/reflection bridge. These are specified in the manual to be exactly 24" long, 50 ohms and terminated by N-type plugs. I've been told the length of these patch leads is quite critical to getting accurate measurements with this VNA, but am at a loss to work out why 24" is specified when the frequency range of this device is 4Mhz to 1300Mhz. If it were only capable of measuring at one fixed frequency, I could understand the need for a specifically cut length of some fraction of a wavelength. Can anyone explain the relevance of 24" in this context? Also, will *any* 50 ohm coax suffice for this purpose or has it got to be something special? Thanks, P. -- "What is now proved was once only imagin'd" - William Blake Article: 219751 of rec.radio.amateur.antenna From: "Fred W4JLE" References: <1133576906.890685.201870@g47g2000cwa.googlegroups.com> <9cffe$43911003$97d56a33$7851@ALLTEL.NET> <1133584284.471704.259160@g49g2000cwa.googlegroups.com> Subject: Re: My vertical blew down!!! Date: Sat, 3 Dec 2005 12:20:29 -0500 Message-ID: The pipe thread area is a point of weakness and the overlap is way to short to provide any strength. A better alternative is aluminum tubing with .058 wall thickness. This allows decending sizes to fit with in one another. For example a 1" 6061 T6 10 foot long has an inside diameter of .884 and a 10 foot section of 7/8" (.875) will slide right into it. This would allow an overlap of almost 4 feet providing all the strength you need. Good luck on your next installation. wrote in message news:1133584284.471704.259160@g49g2000cwa.googlegroups.com... > Ground system: > > 5 foot of 1 inch diameter galvanized iron pipe, halfway stuck in ground > with concrete. > 1 inch diameter galvanized coupler > 5 foot of 1 inch diameter galvanized pipe > 1 inch to 3/4 inch copper reducer > 1 foot of 3/4 inch copper pipe > 4 tees: 3/4 inch thru vs 1/2 inch out, soldered lengthwise along > copper pipe. > an 8 foot length of 1/2 inch copper pipe soldered into each tee > tees are reinforced above and below radials with a hose clamp > coax shield connected to top of copper pipe > > Radiator: > 10 feet of 3/4 inch diameter copper pipe > 9 foot carbon fiber fishing rod, handle epoxied and inserted into pipe > a wire is attached to copper pipe and run up to end of rod. > Hot end of coax connected to bottom of copper pipe > > Ground system and Radiator are connected in-line with a PVC twist shaft > coupler designed for 3/4 inch pipe, weather sealed with epoxy. A gap > of 1 inch between pipes inside the coupler is filled with styrofoam to > prevent contact. > > Rope guys are econnected to the top part of the shaft coupler, as the > middle of the shaft coupler is predicted to be weakest point. > > Sure enough, a continuous wind in excess of 60 mph vibrated the shaft > coupler into 2 pieces despite the guys, the radiator then collided with > a radial, knocking a radial out of alignment and ripping apart a hose > clamp. I suspect the wind is going to finish the job overnight. > > Sigh, > > The Eternal Squire > Article: 219752 of rec.radio.amateur.antenna From: toor@iquest.net (John S. Dyson) Subject: Re: Am Antenna Help Date: Sat, 3 Dec 2005 18:48:38 +0000 (UTC) Message-ID: References: <11oos4qo1fo1dd2@corp.supernews.com> In article <11otv7q7vq0a450@corp.supernews.com>, "Jeff Dieterle" writes: >>>> You never mention how far away you are from "... Indianapolis 1070kc and >>>> Chicago 670kc & 1000kc." That'll have a LARGE bearing on the day/night >>>> reception question. >>>> >>>> Jonesy >>>> -- >>>> Marvin L Jones | jonz | W3DHJ | linux >>>> Pueblo, Colorado | @ | Jonesy | OS/2 __ >>>> 38.24N 104.55W | config.com | DM78rf | SK > > I'm 70mi from Indy and 120mi from Chicago. Chicago 670kc is reasonable at > night 1070kc out of Indy at night is pretty bad. > Is 40ft at right angles to these signals better that 200ft parallel? > (This doesn't solve your problem, but might give you some info as to why the reception of WIBC is somewhat difficult.) Given your distances, then you are somewhere between Indy and Chicago. WIBC drops their power significantly at night, and also the antenna pattern shows that the available signal is probably the worst possible given the antenna :-(. Here is a picture of the WIBC pattern, and consider the WIBC towers are on the NW side of Indy. http://www.fcc.gov/Bureaus/MB/Databases/AM_DA_patterns/306964-6786.pdf John Article: 219753 of rec.radio.amateur.antenna From: "Henry Kiefer" References: <439182de$0$20842$9b4e6d93@newsread2.arcor-online.net> Subject: Re: OFF TOPIC, but how do y'all read these news groups? Date: Sat, 3 Dec 2005 20:22:09 +0100 Message-ID: <4391f3de$0$20858$9b4e6d93@newsread2.arcor-online.net> Google interface is nice but overloaded. I prefer to offline action what is not possible with Google. - Henry "Al" schrieb im Newsbeitrag news:no.spam-FAB984.11582403122005@news.verizon.net... > In article <439182de$0$20842$9b4e6d93@newsread2.arcor-online.net>, > "Henry Kiefer" wrote: > > > I used news.cis.dfn.de a while but changed to arcor-news later because of > > the now charging at news.cis.dfn.de > > Arcor is still free and fast, no reliable problems. You must have a Arcor > > login but this is even a free mail-account. If you like I can you send > > instructions where. I don't know it just if the head. > > Maybe they filter not-german clients out via your IP-address. But why not > > give it a try? > > > > Sent via Arcor - > > Henry > > > > > > > So, you being a *nix user, I can't see you getting excited about doing > > > usenet 'text work' with a bloated cartoon interface. I'm a *nix user, > > > too, and I can recommend Individual.net ( http://news.individual.net/ ). > > > It's is the follow-on/re-incarnation of the free news.cis.dfn.de. It > > > costs 10 Euro per year and it's well worth it. I used the online sign-up > > > and paid via the FirstgGate ( http://firstgate.com/EU/en/info.html ) > > > service they use. > > > > > > Now, if only slrn could score on top-posters. sigh... > > > > > > HTH > > > Jonesy > > > -- > > > Marvin L Jones | jonz | W3DHJ | linux > > > Pueblo, Colorado | @ | Jonesy | OS/2 __ > > > 38.24N 104.55W | config.com | DM78rf | SK > > > > > > I have used the Google newsgroups on occasion. All you need is a > browser. I don't care for the interface though. > > Al Article: 219754 of rec.radio.amateur.antenna From: Owen Duffy Subject: Re: Short coax interconnections - phase implications?? Message-ID: References: <1bh3p11kcftnc9rtrhfihqc7r2olhe2oqj@4ax.com> <2N2dnc9hUZCragzeRVn-rg@comcast.com> Date: Sat, 03 Dec 2005 21:03:05 GMT On Sat, 3 Dec 2005 11:51:14 -0800, "Jim" wrote: > The phase velocity for most coax cables are similar, so I'd use RG-8 since >that accepts type N connectors reasonably well. The impedance bump caused >by a thinner cable being adapted to type N cables would be noticeable >especially at higher frequencies. > > The only major question is whether the original cables had a different >velocity factor, and that I can't answer so I'd use the RG-8 and it should >be close enough. Is the Zo of RG8 52 ohms? Is the instrument 50 ohms? Would RG8 introduce error? Owen -- Article: 219755 of rec.radio.amateur.antenna From: Paul Burridge Subject: Re: Short coax interconnections - phase implications?? Date: Sun, 04 Dec 2005 00:45:00 +0100 Message-ID: <3va4p19gdprae1j65nsn7nr2bccmfrfou6@4ax.com> References: On Sat, 03 Dec 2005 14:50:02 -0700, Wes Stewart wrote: >Maybe a mention of the model number would be helpful. Thanks Wes (and others - I'm building up a picture of what's what from your contributions...) The VNA in question is an HP 8754A made in about 1979. >My best guess >is that the absolute length is not very important as long as all three >are the same length. That would explain a lot. >The stability of the cable is likely more important than the exact >type. Yup. So I've been given to understand. But is the loss factor relevant over just 2 feet at 1300Mhz? BTW, the guy that asked about the impedance of RG8: it *is* 50 ohms as far as I can ascertain and if it *were* 52, it surely *would* screw up the measurement, IMHE! -- "What is now proved was once only imagin'd" - William Blake Article: 219756 of rec.radio.amateur.antenna From: "Frank" References: Subject: Re: how to measure antenna impedance ? Message-ID: Date: Sun, 04 Dec 2005 03:35:40 GMT > I am trying to measure antenna impedance. For this I intend to us a > directional coupler to isolate reflected signal. After using the coupler > for a while I believe that it introduces a phase shift, that shift seems > to be related to frequency. This creates a bit of a catch 22. Antenna > resonance is defined as the frequency where there is no reflected complex > component. If the tool to measure this is also frequency dependent how can > this be accomplished? Is this even the best method? > > Do bi-directional couplers automatically compensate for frequency shift? > > Thanks - Dan kb0qil What you are measuring with a directional coupler is the complex reflection coeficiant. If the measurement is for low frequencies (i.e. < 30 MHz), and the load is at the input of the directional coupler, then you will probably obtain a realistic figure for complex "Gamma". Ideally you need a short circuit, open circuit, and 50 ohm load to determine if the system is calibrated. Short circuit Gamma = 1 <180 Open circuit Gamma = 1< 0 50 Ohm Gamma = 0 If the load is at the end of a length of coaxial cable you have to comphensate for the phase shift error at every measurement frequency. Since you are dealing with complex numbers it is tedious to determine the actual load impedance. The following app. note should help: http://www.maxim-ic.com/appnotes.cfm/appnote_number/742 HP's app. note at http://www.sss-mag.com/pdf/hpan95-1.pdf is also very helpful. Regards, Frank Article: 219757 of rec.radio.amateur.antenna From: Roy Lewallen Subject: Re: Antenna reception theory Date: Sat, 03 Dec 2005 20:03:21 -0800 Message-ID: <11p4qke5i7jv82b@corp.supernews.com> References: <7955-43907316-416@storefull-3256.bay.webtv.net> <11p322i7mfa917d@corp.supernews.com> Reg Edwards wrote: > Roy, > > What is the voltage measured between the bottom-end of a 1 metre > vertical antenna and a perfect ground when the field strength is 1 V/m > and the wavelength is >> 1 m. 1 volt. Roy Lewallen, W7EL Article: 219758 of rec.radio.amateur.antenna From: Bob Bob Subject: Re: how to measure antenna impedance ? References: Message-ID: <5k4a63-oo2.ln1@p400bob.personal.cox.net> Date: Sat, 03 Dec 2005 21:32:52 -0600 Hi Dan Normally you would calibrate your test gear against a known resistive load first. If you coupler creates a phase shift that can be compensated for either in the test equipment or by varying the feedline length. (ouch!) All the network analysers I have used allow you to calibrate 50r, open or short. You can further test you setup by measuring known lengths of coax "stubs" that would present a reactive load. I imagine a directional coupler would introduce a phase shift as it has an electrical length that must be allowed for. I saw a real impressive antenna impedence measuring device that used coaxial cable as the tuned reference elements. It was of course frequency dependent. It was made for 2M but I guess the design would be easy to replicate for other frequencies given. It has about 10% usable bandwidth. I was going to make one for HF with BNC terminated coax lengths for each band, but never did! Go to http://www.vhfdx.oz-hams.org/and Measurements or http://www.vhfdx.oz-hams.org/docs/ZMeterVK2ZAB.pdf Apologies for not answering your exact questions. Cheers Bob W5/VK2YQA dansawyeror wrote: > > > All, > > I am trying to measure antenna impedance. For this I intend to us a > directional coupler to isolate reflected signal. After using the coupler > for a while I believe that it introduces a phase shift, that shift seems > to be related to frequency. This creates a bit of a catch 22. Antenna > resonance is defined as the frequency where there is no reflected > complex component. If the tool to measure this is also frequency > dependent how can this be accomplished? Is this even the best method? > > Do bi-directional couplers automatically compensate for frequency shift? > > Thanks - Dan kb0qil Article: 219759 of rec.radio.amateur.antenna From: Roy Lewallen Subject: Re: how to measure antenna impedance ? Date: Sat, 03 Dec 2005 21:13:36 -0800 Message-ID: <11p4uo5eo3in7ac@corp.supernews.com> References: <5k4a63-oo2.ln1@p400bob.personal.cox.net> Network analyzers incorporate a concept called a "reference plane". This is a theoretical point at which the measurement is actually made. It's desirable to have this point be at the DUT connector. (In precision and/or extremely high frequency measurements, the point within the connector becomes important, and even a sex-change adapter can't be tolerated between calibration and measurement.) Software in the network analyzer is told where the reference plane is to be by means of a rather involved calibration procedure, then the network's software corrects for the phase shift and impedance magnitude transformation of the cable between the reference plane and the analyzer itself. It effectively makes the reference plane the point being measured, rather than the analyzer input terminal. When you make manual measurements, you have to do the correction yourself. So what you need to know is the impedance and length of the line between your point of measurement and the DUT. This can be determined in the same way as it's done for some network analyzer calibrations -- by measuring the impedance with the DUT replaced with a short circuit, an open circuit, and a known load impedance, then solving the resulting set of simultaneous equations. Once you know the impedance and length of the cable between where your measurement is correct and the DUT, you can calculate the actual DUT impedance from your measured value. I do this routinely at HF, when I measure antenna impedance at the input end of a transmission line. Accuracy is best when the impedance being measured isn't far from the Z0 of the transmission line, and the transmission line is short. The longer the line and the greater the difference between line Z0 and DUT impedance, the greater the sensitivity to measurement error in both the measured DUT impedance and the line Z0 and length. A surprisingly small amount of line loss can also skew the measurements quite badly if Z0 and DUT impedance are quite different. If you need accurate results, you should do an error analysis to see how far off your calculated result can be, given the estimated accuracy of your measurement and calibration. As I mentioned in my earlier posting, most people overestimate their ability to make accurate RF measurements. It's not at all trivial. Be sure to check your results frequently by measuring known load impedances close to the values being measured. How do you find the values of those "known" load impedances? Well, welcome to the world of metrology! Roy Lewallen, W7EL Article: 219760 of rec.radio.amateur.antenna From: "Reg Edwards" Subject: Re: Antenna reception theory Date: Sun, 4 Dec 2005 06:26:29 +0000 (UTC) Message-ID: References: <7955-43907316-416@storefull-3256.bay.webtv.net> <11p322i7mfa917d@corp.supernews.com> <11p4qke5i7jv82b@corp.supernews.com> "Roy Lewallen" wrote in message news:11p4qke5i7jv82b@corp.supernews.com... > Reg Edwards wrote: > > Roy, > > > > What is the voltage measured between the bottom-end of a 1 metre > > vertical antenna and a perfect ground when the field strength is 1 V/m > > and the wavelength is >> 1 m. > > 1 volt. > > Roy Lewallen, W7EL ======================================== Thank you Roy. I don't doubt that your answer conforms to the learned text books on the subject. But I am suspicious the text books may be wrong. I will do some calculations related to radiation resistance and power available to a matched receiver. If I think my suspicions are correct then I will come back to you. ---- Reg. Article: 219761 of rec.radio.amateur.antenna From: Roy Lewallen Subject: Re: how to model frequency response of a loaded vertical ? Date: Sat, 03 Dec 2005 22:43:16 -0800 Message-ID: <11p540b8oe5ig71@corp.supernews.com> References: <11p2d12qnuu0m52@corp.supernews.com> <4391F662.9070707@comcast.net> I apologize -- I read your earlier posting too hastily. Your antenna requires the full version of EZNEC because of the inductor. While a short inductor can be modeled as a lumped load, that doesn't work well in cases like this where the current changes significantly from one end of the coil to the other due to radiation. The coil has to be modeled as a helix. A full model of your antenna with the coil properly modeled shows a feedpoint impedance of 5.03 - j212 ohms at 112 MHz over perfect ground. Loss in a real ground system will of course increase the resistance. It resonates at 171 MHz, where the feedpoint resistance is about 17 ohms. My result is far from your finding of resonance around 112 MHz, so maybe I didn't interpret the design correctly -- the antenna I modeled is a total of 11 inches high, the center 3 inches of that being the 1 inch diameter 5 turn coil. With EZNEC and similar programs, you can only connect directly only to perfect and MININEC-type ground; connection to Real, High-Accuracy ground results in an unpredictable resistance that has no physical meaning. More information can be found in the Modeling Ground chapter of the EZNEC manual under Building The Model. Roy Lewallen, W7EL dansawyeror wrote: > Roy, > > Thanks, I was able to enter the data into eznec and run the simulation. > The output was 'confusing'. Eznec predicted 100 Ohm over various > grounds. Other models predict 5 Ohms for the antenna plus ground > resistance with a total of 10 Ohms or so. Which is correct? How can the > differences be reconciled? > > Thanks again - Dan > > Roy Lewallen wrote: > >> dansawyeror wrote: >> >>> All, >>> >>> I am creating a 'scaled' model of a loaded vertical. The model is >>> complete and in place. However I immediately realized I had no idea >>> of the 'theoretical' response. How can I calculate the expected >>> impedance response of a loaded vertical? It a mid load construction, >>> >>> the base in #10 solid copper 4 inchs, >>> the coil is .6 pitch, 1 inch diameter, 5 turns #12, measuring .72 uH, >>> and the top is 4 inch #12. >>> >>> The antenna appears to resonate at about 112 MHz. >>> >>> The instrumentation, a directional coupler measuring reflection is >>> located at the base, directly under the 'ground plane'. This allows >>> measuring input and reflected signal strength. >>> >>> The question is: How can I plot the expected impedance from say 100 >>> MHz to 130 MHz? >>> >>> Thanks - Dan >> >> >> >> The free EZNEC demo from http://eznec.com will give you the >> information you need. >> >> Roy Lewallen, W7EL Article: 219762 of rec.radio.amateur.antenna From: Roy Lewallen Subject: Re: Antenna reception theory Date: Sat, 03 Dec 2005 22:57:07 -0800 Message-ID: <11p54qa720fpf1b@corp.supernews.com> References: <7955-43907316-416@storefull-3256.bay.webtv.net> <11p322i7mfa917d@corp.supernews.com> <11p4qke5i7jv82b@corp.supernews.com> Reg Edwards wrote: > Thank you Roy. > > I don't doubt that your answer conforms to the learned text books on > the subject. But I am suspicious the text books may be wrong. > > I will do some calculations related to radiation resistance and power > available to a matched receiver. If I think my suspicions are correct > then I will come back to you. > ---- > Reg. To tell the truth, I got the result for a wire over ground from an NEC-2 model, after first checking to make sure I got the theoretical 0.5 volt for the center of a dipole in free space. (NEC-2 has provision for applying a plane wave to the model.) In the process of confirming the 0.5 volt value, I found an error in a popular text, Balanis, _Antenna Theory, Analysis and Design_. On p. 61, he incorrectly states that the current along a short dipole "can be assumed to be constant", which isn't true, and from that concludes that the "induced voltage" would be 1 volt when the dipole feedpoint is short circuited. How he defines "induced voltage" with a shorted feepoint isn't clear, but the uniform current assumption he used to get it is incorrect. Kraus, in _Antennas_, and others get it right, and modeling confirms it. Roy Lewallen, W7EL Article: 219763 of rec.radio.amateur.antenna From: "Reg Edwards" Subject: Re: Antenna reception theory Date: Sun, 4 Dec 2005 08:11:26 +0000 (UTC) Message-ID: References: <7955-43907316-416@storefull-3256.bay.webtv.net> <11p322i7mfa917d@corp.supernews.com> <11p4qke5i7jv82b@corp.supernews.com> <11p54qa720fpf1b@corp.supernews.com> Roy, you have anticipated my thoughts on the subject. Nevertheless, I will do some calculations. The proof of the pudding lies in the type of computer programs whose input data does not depend on unreliabe human imagination about antenna gain, mirror images and reflections from the ground. I have no access to the learned text books or computer programs. ---- Reg, G4FGQ Article: 219764 of rec.radio.amateur.antenna From: "Reg Edwards" Subject: Re: how to model frequency response of a loaded vertical ? Date: Sun, 4 Dec 2005 08:39:20 +0000 (UTC) Message-ID: References: <11p2d12qnuu0m52@corp.supernews.com> <4391F662.9070707@comcast.net> <11p540b8oe5ig71@corp.supernews.com> Roy said - > While a > short inductor can be modeled as a lumped load, that doesn't work well > in cases like this where the current changes significantly from one end > of the coil to the other due to radiation. The coil has to be modeled as > a helix. > ======================================= The non-uniform current does not arise from radiation but from the distributed capacitance of the wire turns on the helix to its surroundings. Distributed inductance and capacitance of the helix behave as a short transmission line and there is a corresponding phase shift between one end and the other in addition to the non-uniform current distribution. The effects can be estimated by approximate calculations with an adequate degree of accuracy but it requires the right type of computer program (which probably doesn't exist) to provide exact answers. ---- Reg. Article: 219765 of rec.radio.amateur.antenna From: Roy Lewallen Subject: Re: Antenna reception theory Date: Sun, 04 Dec 2005 00:53:59 -0800 Message-ID: <11p5blcru430q9d@corp.supernews.com> References: <7955-43907316-416@storefull-3256.bay.webtv.net> <11p322i7mfa917d@corp.supernews.com> <11p4qke5i7jv82b@corp.supernews.com> <11p54qa720fpf1b@corp.supernews.com> Reg Edwards wrote: > Roy, you have anticipated my thoughts on the subject. > > Nevertheless, I will do some calculations. You should be able to reason the wire-over-ground case as follows: Imagine a plane wave of 2 V/m intensity striking a 2 m long open circuited dipole in free space. The open circuit voltage should be 4 times as great as it would be for a 1 V/m wave striking a 1 m long dipole. If you bisect the system with a ground plane, you have half the dipole and half the field above ground -- that's a 1 m wire and 1 V/m field. And half the original dipole's voltage appears between the bottom end of the wire and ground. So the resulting voltage is twice what it would be at the center of a 1 m dipole in free space. > The proof of the pudding lies in the type of computer programs whose > input data does not depend on unreliabe human imagination about > antenna gain, mirror images and reflections from the ground. I have no idea what you're talking about there, but I'm sure that whatever it is, it must not apply to the programs you write. > I have no access to the learned text books or computer programs. Sure you do, as does anyone with access to this newsgroup. Texts are readily available by web order for the price of a very few bottles of mediocre wine. Some have even been scanned and posted on the web. And NEC-2 is free and can be downloaded from the web. But some people just can't deal with any idea they didn't come up with on their own -- we call it the NIH (Not Invented Here) syndrome. But each to his own. Enjoy tonight's Balanis. You can save the Kraus for a special occasion. Roy Lewallen, W7EL Article: 219766 of rec.radio.amateur.antenna From: Roy Lewallen Subject: Re: how to model frequency response of a loaded vertical ? Date: Sun, 04 Dec 2005 01:41:49 -0800 Message-ID: <11p5ef2igc49jcd@corp.supernews.com> References: <11p2d12qnuu0m52@corp.supernews.com> <4391F662.9070707@comcast.net> <11p540b8oe5ig71@corp.supernews.com> Reg Edwards wrote: > Roy said - > >>While a >>short inductor can be modeled as a lumped load, that doesn't work > > well > >>in cases like this where the current changes significantly from one > > end > >>of the coil to the other due to radiation. The coil has to be > > modeled as > >>a helix. >> > > ======================================= > The non-uniform current does not arise from radiation but from the > distributed capacitance of the wire turns on the helix to its > surroundings. You're correct. I apologize for the error. > Distributed inductance and capacitance of the helix behave as a short > transmission line and there is a corresponding phase shift between one > end and the other in addition to the non-uniform current distribution. > > The effects can be estimated by approximate calculations with an > adequate degree of accuracy but it requires the right type of computer > program (which probably doesn't exist) to provide exact answers. Moment method programs such as NEC-2, EZNEC, or even MININEC, do a very good job. Roy Lewallen, W7EL Article: 219767 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: how to model frequency response of a loaded vertical ? References: <11p2d12qnuu0m52@corp.supernews.com> <4391F662.9070707@comcast.net> <11p540b8oe5ig71@corp.supernews.com> Message-ID: <3RDkf.21818$BZ5.10421@newssvr13.news.prodigy.com> Date: Sun, 04 Dec 2005 15:22:39 GMT Reg Edwards wrote: > The non-uniform current does not arise from radiation but from the > distributed capacitance of the wire turns on the helix to its > surroundings. How about the fact that it is a *standing wave antenna* with a forward traveling wave in one direction and a reverse traveling wave in the other direction? The net current is the sum of those two current components and their phasors are rotating in opposite directions. -- 73, Cecil http://www.qsl.net/w5dxp Article: 219768 of rec.radio.amateur.antenna From: Paul Burridge Subject: Re: how to measure antenna impedance ? Date: Sun, 04 Dec 2005 15:25:51 +0100 Message-ID: <9mu5p1limi4t4d21ojj28rnrqq74vcmh2j@4ax.com> References: <5k4a63-oo2.ln1@p400bob.personal.cox.net> <11p4uo5eo3in7ac@corp.supernews.com> On Sat, 03 Dec 2005 21:13:36 -0800, Roy Lewallen wrote: >As I mentioned in my earlier posting, most people overestimate their >ability to make accurate RF measurements. It's not at all trivial. Be >sure to check your results frequently by measuring known load impedances >close to the values being measured. How do you find the values of those >"known" load impedances? Well, welcome to the world of metrology! Roy, I've seen your postings hereabouts over the years and you've always struck me as one of the most knowledgeable posters on this, *the* most technically-challenging of all hobbies. I've recently bought a VNA and am going about the laborious process of setting it up with precisely-cut interconnects to the T/R bridge. Next thing I need to know is... Say I have a mica capacitor (for example) that I want to check for its SRF. How should I mount this component so as to minimize stray L&C >from anything other than the component itself? IOW, what 'platform' (for want of a better word) do I need to construct to permit accurate measurements of this cap's RF characteristics in isolation? Thanks, Paul -- "What is now proved was once only imagin'd" - William Blake Article: 219769 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Antenna reception theory References: <7955-43907316-416@storefull-3256.bay.webtv.net> <11p322i7mfa917d@corp.supernews.com> <11p4qke5i7jv82b@corp.supernews.com> <11p54qa720fpf1b@corp.supernews.com> <11p5blcru430q9d@corp.supernews.com> Message-ID: Date: Sun, 04 Dec 2005 15:26:17 GMT Roy Lewallen wrote: > But some people just > can't deal with any idea they didn't come up with on their own ... You mean like Ptotal = P1 + P2 + 2*SQRT(P1*P2)cos(a) ? :-) The first time I saw that equation was in Dr. Best's QEX article. -- 73, Cecil http://www.qsl.net/w5dxp Article: 219770 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Antenna reception theory References: <7955-43907316-416@storefull-3256.bay.webtv.net> <11p322i7mfa917d@corp.supernews.com> <11p4qke5i7jv82b@corp.supernews.com> <11p54qa720fpf1b@corp.supernews.com> Message-ID: Date: Sun, 04 Dec 2005 15:30:46 GMT Roy Lewallen wrote: > In the process of confirming the 0.5 volt value, I found an error in a > popular text, Balanis, _Antenna Theory, Analysis and Design_. On p. 61, > he incorrectly states that the current along a short dipole "can be > assumed to be constant", which isn't true, ... You must have the 1st edition. In the second edition Balanis says on page 133 that the current on an infinitesimal dipole can be considered to be constant. On page 143 he says the current along a small dipole is triangular shaped. -- 73, Cecil http://www.qsl.net/w5dxp Article: 219771 of rec.radio.amateur.antenna Message-ID: <43931CF9.43731F8B@shaw.ca> From: Irv Finkleman Subject: Re: help: antenna inside a box References: <1133681998.929717.153920@o13g2000cwo.googlegroups.com> Date: Sun, 04 Dec 2005 16:44:45 GMT jinlu8591@yahoo.com wrote: > > A RF module was integrated with an application. The whole system > including the RF module, antenna and application components must be put > inside a plastic box (per the users' requirement). Unfortunately, the > application components include a transformer and some other metal > components, and the box (designed beyond my control) is small, and the > antenna is very close to these metal comonents inside the plastic box > (very little room inside the box). I found the RF performance (e.g. > Tx/Rx distance) is much weaker than if the antenna is farther separated > from the the other components (for example, let the antenna stick out > of the box...). Could you make some suggestions or guidelines to deal > with this situation so that the RF performance is as good as if the > antenna is stick out of the box .... > > Thanks for your help. > > Jin If you were to make the antenna a ground plane or vertical and use a piece of copper clad circuit board as the plane, it might provide a good degree of isolation from the other components below that plane. Irv -- -------------------------------------- Diagnosed Type II Diabetes March 5 2001 Beating it with diet and exercise! 297/215/210 (to be revised lower) 58"/43"(!)/44" (already lower too!) -------------------------------------- Visit my HomePage at http://members.shaw.ca/finkirv/index.html Visit my Baby Sofia website at http://members.shaw.ca/finkirv4/index.htm Visit my OLDTIMERS website at http://members.shaw.ca/finkirv5/index.htm -------------------- Irv Finkleman, Grampa/Ex-Navy/Old Fart/Ham Radio VE6BP Calgary, Alberta, Canada Article: 219772 of rec.radio.amateur.antenna From: Gene Fuller Subject: Re: Antenna reception theory References: <11opb3rakuceo3d@corp.supernews.com> <26586-438F5A99-1152@storefull-3253.bay.webtv.net> Message-ID: Date: Sun, 04 Dec 2005 17:17:03 GMT Richard, Terman said no such thing, and your interpretation is clearly in error. Magnetic fields cannot impart ANY energy to charges, such as electrons in a wire. This is because the force from a magnetic field on a charge is always perpendicular to the motion of the charge. No work can be done by the magnetic field, and the energy of the electrons does not change. Only electric fields can provide energy to an electron. Fortunately, Faraday's Law saves the day. Changing magnetic flux is inextricably intertwined with electromotive force. Terman's comment on page 2 of the 1955 edition simply points out the operation of Faraday's Law. (Yes, I have this volume of Terman.) Your conclusion statement is completely reversed. The magnetic field does nothing to induce current in the antenna, while the electric field does everything. Again, however, the laws of physics save the day. Maxwell's equations link electric and magnetic fields in such a manner that the magnetic field you favor creates just enough electric field to drive the electrons in the wire. As has been stated many times in this newsgroup, it is not possible to filter out one field component or the other. As long as there is some time dependence, i.e., other than purely static fields, both the electric and magnetic fields coexist. 73, Gene W4SZ Richard Harrison wrote: > Roy Lewallen wrote: > "You can find the explanation for why this is in any electromagnetic > text." > > I found it in Terman. > > As we all know, we place correctly polarized dipoles, for example, > parallel to the wavefront for maximum response. Terman confirms the > electric field in this instance induces no energy in the antenna. It all > comes from the magnetic field. > > If antenna current flows, no matter where it comes from, loss resistance > causes a voltge drop. That`s why the wire needs to be perfect. The > electric field produces no voltage in the antenna because the wavefront > has the same voltage across its entire surface. That`s because it all > left the same point at the same time. So, a wire parallel to the front > has no difference of potential induced by the wavefront`s electric > field. It all must come from the mgnetic field. > > On page 2 of his 1955 edition, Terman says: > "The strength of the wave measured in terms of microvolts per meter of > stress in space is also exactly the same voltage that the MAGNETIC FLUX > (my emphasis) of the wave induces in a conductor 1 m long when sweeping > across this conductor with the velocity of light." > > From the above, it is seen that the electric field is not effective in > inducing current in a receiving antenna parallel to a wavefront. All the > energy intercepted by the antenna is induced by the magnetic field. > > Best regards, Richard Harrison, KB5WZI > Article: 219773 of rec.radio.amateur.antenna From: "Frank" References: <4393122A.4040108@comcast.net> Subject: Re: how to measure antenna impedance ? Message-ID: Date: Sun, 04 Dec 2005 17:41:46 GMT > Your answer to the question about bidirectional couplers was they do not > compensate for phase shift. Let me ask it again: > > Do the measuring ports of a bi-directional coupler accurately represent or > preserve the relative phases of the signal? > > To put it another way is the phase shift of the driving and reflected > signals changed by the same about? > > Thanks - Dan kb0qil The phases seen at each coupled port should be identical to the phase of the forward and reflected signals. This is easily verifiable, and frequency independant, as follows: No load -- forward and reverse amplitudes equal, and in phase; Short circuit at output -- forward and reverse amplitudes equal, and 180 degrees phase difference; 50 ohm load -- reverse < than forward by <= specified coupler directivity, and phase difference can 0< theta < +/ 180. This is only true if the frequencies are low enough such that the standards do not require quantification by the use of "Standard definitions" -- see www.vnahelp.com. Regards, Frank Article: 219774 of rec.radio.amateur.antenna From: John Ferrell Subject: Re: bidirectional 440 yagi antenna Message-ID: References: Date: Sun, 04 Dec 2005 19:15:54 GMT Great! It sounds like you have it well planned. I was afraid you were one of those fellows who thought it is a trivial problem. I have a little experience(old) in ATV on 439 and current experience in RC. You have probably already planned for these things but let me share observations: All antennas with gain have reduced bandwidth.. a TV signal without sound requires at least 4mhz without degradation. All antennas with gain have reduced beam width. A little yaw with anything resembling a yagi is going to be very noticeable. It is easier to get gain at the receiving end than the transmitting end. My 48 element collinear was very wide band and measured 21 db gain. It is 3X5 feet. Good luck, John Ferrell W8CCW PS, AMA insurance specially excludes autonomous flight. On Sat, 03 Dec 2005 11:00:06 -0600, Chris W <1qazse4@cox.net> wrote: >John Ferrell wrote: > >>A simple dipole will do what you want. That is a lot of power in the John Ferrell W8CCW Article: 219775 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: how to measure antenna impedance ? References: <43931203.1070205@comcast.net> Message-ID: <%DHkf.31729$tV6.15975@newssvr27.news.prodigy.net> Date: Sun, 04 Dec 2005 19:41:47 GMT dansawyeror wrote: > Do the measuring ports of a bi-directional coupler accurately represent > or preserve the relative phases of the signal? Let's look at a typical SWR meter sampling circuit. The current is sampled by a one turn primary on a ferrite toroid. The voltage is sampled by a tap on the line close to the point at which the toroid is mounted. At HF frequencies, a wavelength is so long compared to that configuration that physical sample point errors are usually considered to be negligible. That obviously changes at UHF+. No coupler 100% preserves the relative phases. The question is: What is the accuracy? For any configuration, a worst-case accuracy can be specified. At 4 MHz, it's not a problem. At 4 GHz, it's a big problem. At visible light frequencies, most don't even try. -- 73, Cecil http://www.qsl.net/w5dxp Article: 219776 of rec.radio.amateur.antenna From: Roy Lewallen Subject: Re: how to measure antenna impedance ? Date: Sun, 04 Dec 2005 17:08:33 -0800 Message-ID: <11p74on4t8pevba@corp.supernews.com> References: <5k4a63-oo2.ln1@p400bob.personal.cox.net> <11p4uo5eo3in7ac@corp.supernews.com> <9mu5p1limi4t4d21ojj28rnrqq74vcmh2j@4ax.com> Paul Burridge wrote: > On Sat, 03 Dec 2005 21:13:36 -0800, Roy Lewallen > wrote: > > >>As I mentioned in my earlier posting, most people overestimate their >>ability to make accurate RF measurements. It's not at all trivial. Be >>sure to check your results frequently by measuring known load impedances >>close to the values being measured. How do you find the values of those >>"known" load impedances? Well, welcome to the world of metrology! > > > Roy, I've seen your postings hereabouts over the years and you've > always struck me as one of the most knowledgeable posters on this, > *the* most technically-challenging of all hobbies. Thanks for your vote of confidence. But on the topic of network analyzer measurements, I gladly defer to Wes Stewart, Tom Bruhns, and other posters who have spent much more time making real-life measurements with them than I have. I've used them from time to time, and for some really challenging measurements, but not by any means as much as those folks have. > I've recently bought a VNA and am going about the laborious process of > setting it up with precisely-cut interconnects to the T/R bridge. Next > thing I need to know is... > Say I have a mica capacitor (for example) that I want to check for its > SRF. How should I mount this component so as to minimize stray L&C > from anything other than the component itself? IOW, what 'platform' > (for want of a better word) do I need to construct to permit accurate > measurements of this cap's RF characteristics in isolation? In general, you minimize stray inductance by keeping leads short, and capacitance by keeping conductors apart. The ideal setup is a coaxial environment right up to the DUT, but even that is subject to coupling around the DUT, both from one terminal to the other and from each terminal to ground. If possible, the best plan is to calibrate out the strays. That's a science and art in itself, and I'll have to yield to people with more experience than mine for practical information about how best to do this. The effect of the strays depends heavily on what you're measuring. For example, if you're measuring a low impedance, you can get by with more shunt C than if you're measuring a high impedance. If you're measuring a high impedance, you can tolerate more series inductance than when measuring a low impedance. So when you inevitably find that you have to make tradeoffs in designing a fixture, the trades you make will depend on what you expect to measure. Roy Lewallen, W7EL Article: 219777 of rec.radio.amateur.antenna From: "Wayne P. Muckleroy" References: <1bh3p11kcftnc9rtrhfihqc7r2olhe2oqj@4ax.com> Subject: Re: Short coax interconnections - phase implications?? Message-ID: <%JNkf.12425$lh.1687@tornado.ohiordc.rr.com> Date: Mon, 05 Dec 2005 02:37:47 GMT Did you also receive a calibration kit with the VNA? If you did so, then the lengths of these interconnect cables are not crucial for calibrated measurements. Only uncalibrated measurements will be affected. It would help to know the manufacturer and model of the VNA. Wayne (KC8UIO) "Paul Burridge" wrote in message news:1bh3p11kcftnc9rtrhfihqc7r2olhe2oqj@4ax.com... > Hello guys, > > I recently picked up an old vector network analyser in working order > but minus the 3 interconnects between it and the > transmission/reflection bridge. These are specified in the manual to > be exactly 24" long, 50 ohms and terminated by N-type plugs. > I've been told the length of these patch leads is quite critical to > getting accurate measurements with this VNA, but am at a loss to work > out why 24" is specified when the frequency range of this device is > 4Mhz to 1300Mhz. If it were only capable of measuring at one fixed > frequency, I could understand the need for a specifically cut length > of some fraction of a wavelength. > Can anyone explain the relevance of 24" in this context? > Also, will *any* 50 ohm coax suffice for this purpose or has it got to > be something special? > Thanks, > P. > -- > > "What is now proved was once only imagin'd" - William Blake Article: 219778 of rec.radio.amateur.antenna From: crb Subject: What is a duplexer, diplexer and combiner? Date: Sun, 04 Dec 2005 18:50:30 -0800 Message-ID: What are the functions of each of these? Are they used on TX or RX circuits? I know a cell site uses a duplexer so that it has an extra RX antenna for diversity. How does this work? Is the duplexer on the antenna that transmit/receive combo antenna notching out the TX frequency so the receiver doesn't get overloaded by it? Article: 219779 of rec.radio.amateur.antenna From: "Tom Donaly" Subject: Re: Antenna reception theory References: <7955-43907316-416@storefull-3256.bay.webtv.net> <11p322i7mfa917d@corp.supernews.com> <11p4qke5i7jv82b@corp.supernews.com> <11p54qa720fpf1b@corp.supernews.com> <11p5blcru430q9d@corp.supernews.com> Message-ID: Date: Mon, 05 Dec 2005 03:23:00 GMT Cecil Moore wrote: > Roy Lewallen wrote: > >> But some people just can't deal with any idea they didn't come up with >> on their own ... > > > You mean like Ptotal = P1 + P2 + 2*SQRT(P1*P2)cos(a) ? :-) > The first time I saw that equation was in Dr. Best's QEX article. Yes, and you didn't believe it when you saw it. 73, Tom Donaly, KA6RUH Article: 219780 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Antenna reception theory References: <7955-43907316-416@storefull-3256.bay.webtv.net> <11p322i7mfa917d@corp.supernews.com> <11p4qke5i7jv82b@corp.supernews.com> <11p54qa720fpf1b@corp.supernews.com> <11p5blcru430q9d@corp.supernews.com> Message-ID: <7YPkf.26664$dO2.972@newssvr29.news.prodigy.net> Date: Mon, 05 Dec 2005 05:09:23 GMT Tom Donaly wrote: > Cecil Moore wrote: >> You mean like Ptotal = P1 + P2 + 2*SQRT(P1*P2)cos(a) ? :-) >> The first time I saw that equation was in Dr. Best's QEX article. > > Yes, and you didn't believe it when you saw it. Your memory is slightly faulty. What I objected to was Dr. Best's assertion that 75w + 8.33w = 133.33w. It still doesn't, never did, never will, and violates the conservation of energy principle. What Dr. Best apparently failed to realize is that the extra 50 watts of energy required to balance that energy equation does NOT come from waves P1 and P2 but instead comes from wave cancellation of waves P3 and P4 on the source side of the match point. Wave P1 contains 75 watts and Wave P2 contains 8.33 watts. Without a source of constructive interference energy, they cannot add up to 133.33 watts. That source is destructive interference energy, -2*SQRT(P3*P4), from the source side of the match point which supplies the +2*SQRT(P1*P2) constructive interference energy to the load side of the match point where (P1*P2)=(P3*P4). At an impedance discontinuity in a transmission line, far away from any source, all constructive interference energy must necessarily be balanced by an equal magnitude of destructive interference energy in order to satisfy the conservation of energy principle. This is all explained in my "WorldRadio", Oct./Dec. 2005 articles. Unfortunately, most of the Greek letter Thetas didn't make it through the conversion process and wound up as underline marks. Part I is already on my web page under "The Rest of the Story" along with a couple of remarks about forward power, reflected power, superposition, and interference. Part II will appear on my web page after Christmas. -- 73, Cecil http://www.qsl.net/w5dxp Article: 219781 of rec.radio.amateur.antenna From: richardharrison@webtv.net (Richard Harrison) Subject: Re: Antenna reception theory Date: Mon, 5 Dec 2005 08:08:30 -0600 Message-ID: <7977-439449DE-2039@storefull-3255.bay.webtv.net> References: Asimov wrote: "An antenna is just a stationary probe in a moving E-field." Along some path in space there is an electric current which is changing. It is growing or it is shrinking. It is not constant.. This current as a result of its changes radiates electric and magnetic flux. The electric flux lines are are perpendicular to the current path. The magnetic flux lines encircle the current path. The flux is moving away from the current path at the speed of light. At a distant point these electric and magnetic flux lines arrive because they sustain each other during their long trip. There is an initial wavefront. It started as a spherical wavefront but has traveled so far that for practical purposes it is now a plane wave. In the wavefront there is an electric force which would attract or repel electrons but it has the same strength everywhere over the arriving wavefront. Therefore, wlectrons in a wire parallel to the wavefront are not moved along its length by the electric force. This force would only tend to move electrons from one side of the wire`s diameter to the other side of the same diameter. Our interest is in current along the length of the wire. However, the magnetic lines of force are sweping at the speed of light across the wire which parallels the wavefront. If the wire also parallels the direction of the current which generated the lux (is correctly polarized), it will experience a voltage induced all along its length. This induction is totally a result of the magnetic field. Best regards, Richard Harrison, KB5WZI Article: 219782 of rec.radio.amateur.antenna From: "Asimov" Subject: Re: Antenna reception theory Message-ID: References: <7977-439449DE-2039@storefull-3255.bay.webtv.net> Date: Mon, 05 Dec 2005 17:11:06 GMT "Richard Harrison" bravely wrote to "All" (05 Dec 05 08:08:30) --- on the heady topic of "Re: Antenna reception theory" RH> From: richardharrison@webtv.net (Richard Harrison) RH> Xref: core-easynews rec.radio.amateur.antenna:220833 [,,,] RH> There is an initial wavefront. It started as a spherical wavefront but RH> has traveled so far that for practical purposes it is now a plane RH> wave. In the wavefront there is an electric force which would attract RH> or repel electrons but it has the same strength everywhere over the RH> arriving wavefront. Therefore, wlectrons in a wire parallel to the RH> wavefront are not moved along its length by the electric force. This RH> force would only tend to move electrons from one side of the wire`s RH> diameter to the other side of the same diameter. Our interest is in RH> current along the length of the wire. [,,,] There is a time varying voltage gradient in the E field too. Turn the wire around 90" then to find the E gradient. If the wire length is such that one end is positive while the other end is negative then charges will flow inbetween both ends. Anti-static spray won't work on an antenna. A*s*i*m*o*v ... My wife and I always hold hands. If I let go, she shops. Article: 219783 of rec.radio.amateur.antenna From: Jim Kelley Subject: Re: Antenna reception theory Date: Mon, 05 Dec 2005 10:18:50 -0800 Message-ID: References: <7955-43907316-416@storefull-3256.bay.webtv.net> <11p322i7mfa917d@corp.supernews.com> <11p4qke5i7jv82b@corp.supernews.com> <11p54qa720fpf1b@corp.supernews.com> <11p5blcru430q9d@corp.supernews.com> <7YPkf.26664$dO2.972@newssvr29.news.prodigy.net> Cecil Moore wrote: > Tom Donaly wrote: > >> Cecil Moore wrote: >> >>> You mean like Ptotal = P1 + P2 + 2*SQRT(P1*P2)cos(a) ? :-) >>> The first time I saw that equation was in Dr. Best's QEX article. >> >> >> Yes, and you didn't believe it when you saw it. > Wave P1 contains 75 watts and Wave P2 contains 8.33 watts. > Without a source of constructive interference energy, they cannot > add up to 133.33 watts. And obviously he still doesn't believe it, Gene. 73, ac6xg Article: 219784 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Antenna reception theory References: <7955-43907316-416@storefull-3256.bay.webtv.net> <11p322i7mfa917d@corp.supernews.com> <11p4qke5i7jv82b@corp.supernews.com> <11p54qa720fpf1b@corp.supernews.com> <11p5blcru430q9d@corp.supernews.com> <7YPkf.26664$dO2.972@newssvr29.news.prodigy.net> Message-ID: <9Q%kf.31869$tV6.11428@newssvr27.news.prodigy.net> Date: Mon, 05 Dec 2005 18:40:05 GMT Jim Kelley wrote: >> Wave P1 contains 75 watts and Wave P2 contains 8.33 watts. >> Without a source of constructive interference energy, they cannot >> add up to 133.33 watts. > > And obviously he still doesn't believe it, Gene. Without the 2*SQRT(P1*P2)=50w constructive interference energy, 75w + 8.33w will *NEVER* add up to 133.33 watts. Dr. Best's equation, 75w + 8.33w = 133.33w, is superposition of powers which is not allowed AND a violation of the conservation of energy principle. You don't really support superposition of powers and violations of conservation of energy, do you?. If you furnish exactly 75 watts and your neighbor furnishes exactly 8.33 watts, can you power a 133.33 watt device? -- 73, Cecil http://www.qsl.net/w5dxp Article: 219785 of rec.radio.amateur.antenna From: Gene Fuller Subject: Re: Antenna reception theory References: <7955-43907316-416@storefull-3256.bay.webtv.net> <11p322i7mfa917d@corp.supernews.com> <11p4qke5i7jv82b@corp.supernews.com> <11p54qa720fpf1b@corp.supernews.com> <11p5blcru430q9d@corp.supernews.com> <7YPkf.26664$dO2.972@newssvr29.news.prodigy.net> Message-ID: <020lf.125287$qk4.90216@bgtnsc05-news.ops.worldnet.att.net> Date: Mon, 05 Dec 2005 18:54:52 GMT Hi Jim, I was going to try to stay out of this recurring silliness, but since you accidentally pulled me in I will add my spin. The only mistake made by Steve Best was allowing himself to get dragged by Cecil into the intellectual landfill. Yes, most people with rudimentary arithmetic skills would agree that 75 plus 8.33 does not equal 133.33. However, anyone even remotely familiar with waves would readily understand that the component waves Cecil loves to talk about are merely mathematical conveniences. It is entire possible to set up other model configurations, such as a combination of a one traveling wave and one standing wave. In order to make his model work, Cecil needs to invoke the mythical P3 and P4 on the source side of the reflection discontinuity. He never gets around to explaining how these two waves, which exactly cancel at all points in space and at all times, can contain any energy at all. The reason that most practitioners of wave models solve for the fields first and then worry about power or energy is: a - This procedure works correctly all the time. b - It avoids the problems created by analyzing fictitious extra components added for mathematical convenience but containing no physical reality. I do not expect to change Cecil's mind. Other than his own potential embarrassment from the silly publications in World Radio, his folly is harmless. 73, Gene W4SZ Jim Kelley wrote: > > > Cecil Moore wrote: > >> Tom Donaly wrote: >> >>> Cecil Moore wrote: >>> >>>> You mean like Ptotal = P1 + P2 + 2*SQRT(P1*P2)cos(a) ? :-) >>>> The first time I saw that equation was in Dr. Best's QEX article. >>> >>> >>> >>> Yes, and you didn't believe it when you saw it. > > >> Wave P1 contains 75 watts and Wave P2 contains 8.33 watts. >> Without a source of constructive interference energy, they cannot >> add up to 133.33 watts. > > > And obviously he still doesn't believe it, Gene. > > 73, ac6xg > Article: 219786 of rec.radio.amateur.antenna From: richardharrison@webtv.net (Richard Harrison) Subject: Re: Antenna reception theory Date: Mon, 5 Dec 2005 12:53:54 -0600 Message-ID: <9080-43948CC2-1862@storefull-3252.bay.webtv.net> References: Gene, W4SZ wrote: "Terman`s comment on page 2 of the 1955 edition simply points out the operation of Faraday`s Law." Faraday`s law says that, while the magnetic flux linked with a closed path loop or coil is changing, the closed path is the source of an electromotive force (voltage) whose magnitude depends only upon the rate of change of the flux through the path. If we cause an antenna to be surrounded by an altrernating magnetic field, a voltage will be induced in the antenna in accordance with Faraday`s law, This induced voltage is necessary and sufficient to account for all of the energy received by the antenna. Best regards, Richard Harrison, KB5WZI Article: 219787 of rec.radio.amateur.antenna From: "RB" Subject: dipole and balun question Message-ID: <%e0lf.43999$i7.18434@bignews2.bellsouth.net> Date: Mon, 5 Dec 2005 13:10:57 -0600 Some questions about a 140' dipole fed with ladderline from an unbalanced tuner to work 160-10m: 1. Does it matter if the balun is placed on the tuner output, or at the dipole center feedpoint? 2. Which type of balun (voltage/current) would be best for centerfeedpoint use? 4. What ratio balun would be optimal for either application? Article: 219788 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: dipole and balun question References: <%e0lf.43999$i7.18434@bignews2.bellsouth.net> Message-ID: Date: Mon, 05 Dec 2005 19:32:27 GMT RB wrote: > Some questions about a 140' dipole fed with ladderline from an unbalanced > tuner to work 160-10m: > > 1. Does it matter if the balun is placed on the tuner output, or at the > dipole center feedpoint? A balun placed at the dipole center feedpoint has BALanced ladder-line on one side and the BALanced dipole on the other, both of which are balanced. So why on earth would anyone attempt to install a BALanced to UNbalanced device at a point where only balanced environments exist? > 2. Which type of balun (voltage/current) would be best for > centerfeedpoint > use? What you need is a BALBAL. Good luck on finding one at a decent price that works with the impedances you will encounter. > 4. What ratio balun would be optimal for either application? A Balun should only be installed at a BALanced to UNbalanced discontinuity. Forget about trying to install them anywhere else. Most hams who understand what they are doing use a 1:1 choke-balun at the BALanced to UNbalanced point. Take a look at my 130 ft. all-HF-band dipole (click below) -- 73, Cecil http://www.qsl.net/w5dxp/notuner.htm Article: 219789 of rec.radio.amateur.antenna From: richardharrison@webtv.net (Richard Harrison) Subject: Re: Antenna reception theory Date: Mon, 5 Dec 2005 13:38:44 -0600 Message-ID: <25147-43949744-445@storefull-3258.bay.webtv.net> References: Gene, W4SZ write: "As has been said many times on this newsgroup, it is not possible to filter out one field component or the other." Saying it does not make it so. Countless Faraday screens are at work removing the E-field component >from electromagnetic waves. Faraday said that the voltage in a coupled circuit depends only on the rate of change of the magnetic flux through the circuit. He was refering to induced voltage. It was 1831 when Michael Faraday observed the interaction between primary and secondary coils in what was likely the world`s first transformer. Faraday made it himself and noted that the needle of a galvanometer connected across one coil deflected briefly whenever he connected or disconnected a battery across the other coil. Article: 219790 of rec.radio.amateur.antenna From: "Steve Nosko" Subject: Re: What is a duplexer, diplexer and combiner? Date: Mon, 5 Dec 2005 13:09:42 -0600 Message-ID: References: "crb" wrote in message news:dn09hk02r2p@enews1.newsguy.com... > What are the functions of each of these? > > Are they used on TX or RX circuits? > > I know a cell site uses a duplexer so that it > has an extra RX antenna for diversity. How > does this work? Is the duplexer on the antenna > that transmit/receive combo antenna notching > out the TX frequency so the receiver doesn't get > overloaded by it? Crb, These are basically filters. The terminology varies sometimes for "diplexer" and "duplexer", and they are both used to describe the same or different things. I'll give the way they are used in my field - two-way radio and cell phone systems. Duplexer: When we transmit and receive at the same time, this is called duplex operation. A duplexer is designed to allow a transmitter and receiver (operating at slightly differing frequencies) to use the one antenna at the same time. There are several things that must be taken care of in this situation. 1 - The transmitter energy must be kept away from the receiver or it will burn things up. 2 - The transmitter signal can still cause trouble if it is not lowered a lot more than this "blow-up" level. The undesirable effects are commonly intermodulation (mixing of the transmit signal with near-by transmitters which then causes signals which interferes with other receivers) and spurious responses (mixing of the transmitter signal with more distant transmitters which cause signals that interfere with this receiver). 3 - Transmitters also put out noise as you move away from the carrier and this must be reduced to where it does not cover up the desired signal in the receiver. As you probably understand, the difference between the transmitted power and the received signal strength is very great and typically around 170 to 190 dB. To get #1 and #2, a filter is placed in the receive line which passes the received frequency with little loss, but attenuates the transmitter power to a level which keeps the IM products to an acceptable level. To get #3, a filter is placed in the transmitter line which passes the transmit frequency with little loss, but attenuates the noise (and any other spurious which may be there) which the transmitter is producing on the receive frequency. These filters can be band-pass or band-reject (notch) filters. Diplexer / Combiner: These two terms usually refer to devices that allow two transmitters to use one antenna at the same time. However, the term "diplexer" and "duplexer" are used differently in some circles. There are several ways to do this. The term "Combiner" is most common in cellular telephone systems, the term "diplexer" is more common in the military. Combiner: One method (used in cellular transmitters) uses narrow band filters (commonly called cavities). One filter is on the output of each transmitter and, obviously tuned to that transmitter's frequency. Then, to allow these to be all connected at one point so one antenna can be used, transmission lines are used in a special way. These lines are made special lengths such that the following happens. We will consider only two transmitters on two different frequencies here "A" and "B". We look at the junction point where the two filter lines connect to go to the antenna. At frequency "A", the transmission line from filter "B", transforms (rotates around the Smith chart) the impedance of filter "B" such that it is a very high impedance at the junction point. This high impedance across the 50 ohm transmission line accepts little power and therefore disturbs things very little. This means that the power from transmitter "A" only goes to the antenna and not back into transmitter "B". For transmitter "B" just switch the A's and B's in the above. The logical extension of this is for multi transmitter systems where the transmission lines are made such that all filter / transmission line combinations, other than the one frequency going through, appear as a high impedance at the junction. Systems use this technique to connect as many as 20 transmitters to one antenna and the frequencies are quite close together - in the same band. This is a narrow band system and must be re-tuned if the transmit frequencies change. The further apart the frequencies are, the easier it is to make this device. With widely differing frequencies such as 144 MHz and 450 MHz, this can be done with simple low pass and high pass filters. Diplexer: Again I remind you that some use the term "diplexer" and some use the term "duplexer". I believe diplexers are commonly band-pass filters. Using band-pass filters, we can allow the transmitters to move around a bit. I have seen things called diplexers used where the transmitters are in different bands (like 150 MHz and 450 MHz.). There must be the same consideration that I describe above for the impedance at the junction end of the transmission lines coming from the filters where they connect to the common junction point. Finally, because these are filters, they can be used in receive as well as transmit lines. With a two way radio that operates in two bands but only uses one connector - say 144 MHz and 450 MHz. you can use these devices to connect two antennas to the radio, one antenna for 144 MHz and one for 450 Hz. You can also connect two radios, one operating at 144 MHz and one at 450 MHz to an antenna that operates on either band. You can also connect these two radios to a common feed line with a diplexer and then use another diplexer (facing the "other way") to feed two separate antennas for the two frequencies. In the diversity situation you mention, the duplexer saves one antenna that would be needed for transmit by using one of the receive antennas for both receiving and transmitting (duplex). Some systems don't use a duplexer here and do have three antennas. Two for dual diversity receive and one for transmit. You may be able to see this as three vertical bars (antennas) on each side of the triangular top of some cell towers. Hope this helps. 73, Steve, K,9.D;C'I Article: 219791 of rec.radio.amateur.antenna From: "RB" References: <%e0lf.43999$i7.18434@bignews2.bellsouth.net> Subject: Re: dipole and balun question Message-ID: <__0lf.44003$i7.4483@bignews2.bellsouth.net> Date: Mon, 5 Dec 2005 14:02:03 -0600 Oooopss----I meant coax fed. Article: 219792 of rec.radio.amateur.antenna From: richardharrison@webtv.net (Richard Harrison) Subject: Re: Antenna reception theory Date: Mon, 5 Dec 2005 13:58:02 -0600 Message-ID: <25147-43949BCA-447@storefull-3258.bay.webtv.net> References: it is just as easy to remove the H-field from the wave as it is to remove the E-field with a Faraday screen. To remove the H-field, one sure way is to completely enclose two coils so they are completely shielded from each other and all electromagnetic waves. Put the coils in separate metal cans. Put a tiny hole in each can. Conect one termial of each coil to its end of a coupling capcitor. Ground the other terminal of each coil.. Ground is the return path for the coils but it must run on the surfaces of the cans and through the tiny holes due to skin effect. Complete shielding removes the H-field as a coupling agent. Only E-field coupling is provided via the coupling capacitor. Best regards, Richard Harrison, KB5WZI Article: 219793 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Antenna reception theory References: <7955-43907316-416@storefull-3256.bay.webtv.net> <11p322i7mfa917d@corp.supernews.com> <11p4qke5i7jv82b@corp.supernews.com> <11p54qa720fpf1b@corp.supernews.com> <11p5blcru430q9d@corp.supernews.com> <7YPkf.26664$dO2.972@newssvr29.news.prodigy.net> <020lf.125287$qk4.90216@bgtnsc05-news.ops.worldnet.att.net> Message-ID: Date: Mon, 05 Dec 2005 20:09:08 GMT Gene Fuller wrote: > Yes, most people with > rudimentary arithmetic skills would agree that 75 plus 8.33 does not > equal 133.33. Too bad Dr. Best posted the equation: "Ptotal = 75w + 8.33w = 133.33w" on this newsgroup (and, thank goodness, left it out of his article) so he obviously disagreed with you at the time. He also said that interference had nothing to do with it. > However, anyone even remotely familiar with waves would readily > understand that the component waves Cecil loves to talk about are merely > mathematical conveniences. It is entire possible to set up other model > configurations, such as a combination of a one traveling wave and one > standing wave. What happens at an impedance discontinuity given those circumstances? To find out, read my WorldRadio article, Part I of which is posted on my web page. Part II will be posted after Christmas. At the risk of raising your politically incorrect ire as I have done with this technical posting, MERRY CHRISTMAS!. > In order to make his model work, Cecil needs to invoke the mythical P3 > and P4 on the source side of the reflection discontinuity. He never gets > around to explaining how these two waves, which exactly cancel at all > points in space and at all times, can contain any energy at all. The answer is simple. Do waves contain any energy at all? Do waves that cancel contain any energy? If waves contain no energy, they cannot exist, and therefore are incapable of canceling. If they exist and cancel, they contained energy just before their cancellation. Any way you cut it, my approach is consistent with the laws of physics as enumerated in "Optics", by Hecht, and yours leads to a contradiction of those laws of physics. > The reason that most practitioners of wave models solve for the fields > first and then worry about power or energy is: > > a - This procedure works correctly all the time. Yes, it does. But optics engineers didn't have the luxury of dealing with voltages and currents. They had to solve the problem using powers. And they did exactly that decades ago. That RF engineers refuse to consider the laws of physics concerning EM waves developed by optics engineers is absolutely astounding to me. W7EL put it best, something to the effect that if it wasn't invented here, we don't want to hear it (even if it is right). But I daresay that Eugene Hecht knows much more about EM waves that you will ever know, given your closed mind. > I do not expect to change Cecil's mind. Other than his own potential > embarrassment from the silly publications in World Radio, his folly is > harmless. You are just displaying your extreme ignorance, Gene. My "WorldRadio" article corrects some of the *conceptual* errors in Dr. Best's QEX article but otherwise contains the same equations as his article. If you disagree with me, you are also disagreeing with Dr. Best's equations, i.e. you are between a rock and a hard place. It is interesting that the very people who tell us not to worry about energy are the people who get so emotionally rabid when someone chooses to worry about energy like real-world physicists do. What do they possibly have to lose besides face, self-esteem, sleep, and their pseudo-religious guru status? :-) -- 73, Cecil http://www.qsl.net/w5dxp Article: 219794 of rec.radio.amateur.antenna From: Jim Kelley Subject: Re: Antenna reception theory Date: Mon, 05 Dec 2005 12:02:50 -0800 Message-ID: References: <7955-43907316-416@storefull-3256.bay.webtv.net> <11p322i7mfa917d@corp.supernews.com> <11p4qke5i7jv82b@corp.supernews.com> <11p54qa720fpf1b@corp.supernews.com> <11p5blcru430q9d@corp.supernews.com> <7YPkf.26664$dO2.972@newssvr29.news.prodigy.net> <9Q%kf.31869$tV6.11428@newssvr27.news.prodigy.net> Cecil Moore wrote: > Jim Kelley wrote: > >>> Wave P1 contains 75 watts and Wave P2 contains 8.33 watts. >>> Without a source of constructive interference energy, they cannot >>> add up to 133.33 watts. >> >> >> And obviously he still doesn't believe it, Gene. I should have said Tom. If I were Cecil I'd have blamed the error on my glasses or my advanced age. ;-) > You don't really support superposition of > powers and violations of conservation of energy, do you?. Depending on how high you keep your squelch set, you should already pretty well know what I think about those things. You're at least partially right though. Power does not superpose (because, for among other reasons, it doesn't move or propagate). The point you continue to miss is that power does not interfere either. Nor is it valid to take the square root of the product of two power numbers and claim that it turns around miraculously and goes the other direction. But that's what you've miguidedly presented to the readers of World Radio as fact. The irradiance equations are nevertheless correct because power goes as the square of the fields - which do of course superpose and interfere. The equations accurately describe the effect - the end result, the outcome, not necessarily the cause or the mechanism by which the result is achieved. Before we go any further (and it is my sincerest hope that we do not), I agree with Melles-Griot, Born and Wolf, Hecht, Jackson, and the other E&M and optics books. What I disagree with (and I'm sure given the opportunity so would the above mentioned authors) is some of your interpretation of the physical phenomenon they describe. 73, ac6xg Article: 219795 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Antenna reception theory References: <7955-43907316-416@storefull-3256.bay.webtv.net> <11p322i7mfa917d@corp.supernews.com> <11p4qke5i7jv82b@corp.supernews.com> <11p54qa720fpf1b@corp.supernews.com> <11p5blcru430q9d@corp.supernews.com> <7YPkf.26664$dO2.972@newssvr29.news.prodigy.net> <9Q%kf.31869$tV6.11428@newssvr27.news.prodigy.net> Message-ID: Date: Mon, 05 Dec 2005 20:51:39 GMT Jim Kelley wrote: > I should have said Tom. If I were Cecil I'd have blamed the error on my > glasses or my advanced age. ;-) Alzheimer's can certainly strike at your age, Jim. :-) My Dad was legally blind when he was my age so I'm ahead of the curve. > You're at least partially right though. Power does not superpose > (because, for among other reasons, it doesn't move or propagate). The > point you continue to miss is that power does not interfere either. Here's a quote from my magazine article, Jim. If you would just cease and desist from your MF'ing ways (that's "mind", not "muther"), you might understand. Quote: ********************************************************************** "The words 'power flow' have been avoided even though that is a term of common usage. For the purposes of this paper, energy flows and power is a measure of that energy flowing at a fixed point or plane. Likewise, the EM fields in the waves do the interfering. Powers, treaded as scalars, are incapable of interference." ********************************************************************** But you already knew that's what I believe since I have been telling you exactly that in CAPITAL LETTERS for years now and even sent you an advance copy of my magazine article. I have never asserted the things you claim that I have. Hopefully, the readers will recognize you for what you are. > The irradiance equations are nevertheless > correct because power goes as the square of the fields - which do of > course superpose and interfere. The equations accurately describe the > effect - the end result, the outcome, not necessarily the cause or the > mechanism by which the result is achieved. Where does the constructive interference energy come from, Jim? Hecht says that in the absence of energy from other sources, the constructive interference energy must be exactly matched by an equal amount of destructive interference. Please present your credentials that allows you to disagree with Eugene Hecht? > Before we go any further (and it is my sincerest hope that we do not), I > agree with Melles-Griot, ... No you don't, and your disagreement is more than obvious to any informed casual observer. You remind me of a fellow employee from the 70's. I asked him what he would do if his wife caught him in bed with his neighbor's wife (as I did) and he answered, "I'd just deny it." -- 73, Cecil http://www.qsl.net/w5dxp Article: 219796 of rec.radio.amateur.antenna From: Owen Duffy Subject: Re: dipole and balun question Message-ID: References: <%e0lf.43999$i7.18434@bignews2.bellsouth.net> <__0lf.44003$i7.4483@bignews2.bellsouth.net> Date: Mon, 05 Dec 2005 21:14:45 GMT On Mon, 5 Dec 2005 14:02:03 -0600, "RB" wrote: >Oooopss----I meant coax fed. > Did you really? It is unlikely that your proposed antenna system (140' dipole + bal un + coax) feed will provide acceptable losses on many bands, possibly only one band. You have given almost no detail of the antenna (and a key element of the detail was in error), so it is hard to give more a more exact information. If you hadn't mentioned the feed line type, readers would probably have sensibly assumed open wire feed as it is much more likely to be feasible than coax feed of such a multiband dipole. The article at www.vk1od.net/LOLL/index.htm shows in Fig 1 and Fig 1a, antenna system losses for an antenna system comprising a low 66' dipole and coax feed over HF. Your 140' (I am not sure why you didn't nominate 133' which would be resonant on 80m for simplified / lower loss coax feed) would be very roughly a frequency scaled version of the same thing. Owen -- Article: 219797 of rec.radio.amateur.antenna From: Michael Coslo Subject: Re: My vertical blew down!!! Date: Mon, 05 Dec 2005 16:22:55 -0500 Message-ID: References: <1133576906.890685.201870@g47g2000cwa.googlegroups.com> <84rkf.28413$Gd6.6054@pd7tw3no> <1133659754.412000.285590@z14g2000cwz.googlegroups.com> eternalsquire@comcast.net wrote: > > Questions: > > 1) Since I have an 8 foot limit for radials, could I have 1/4 > wavelength helical radials for 40m that could fit into an 8 foot > length? > 1a) Could I do the same helical trick for the radiator as well? > > 2) My base 1 inch diameter galvanized pipe is presently 2 1/2 foot into > a 2 1/2 foot cube concrete filled hole with 2 1/2 foot exposed. What > could I screw in it that would not need guying, and would not bend nor > sway in 100 mph wind, and how high could I make that? > > 3) If I run up a metal pipe to 20 foot and then an insulated wire from > the dirt to the top alongside the pipe as my radiator, what effect will > the pipe have on the radiating wire? Sounds to me like you are trying to fit the wrong antenna into the wrong space. Can you put radials in/on the ground? Can they be longer than 8 feet then? And finally, can you put up a dipole or other wire antenna? If so, your wife isn't going to be too happy when she sees the cost difference between the dipole and what you already spent on the vertical. Dunno if you have many trees in your area or not. But a dipole can be pretty good, esp if money is tight. I have both a dipole (OCF) and a vertical. They both work better than each other.... at certain times. 8^) ALso, what bands are you trying to run? - 73 de Mike KB3EIA - Article: 219798 of rec.radio.amateur.antenna From: Paul Burridge Subject: Re: Short coax interconnections - phase implications?? Date: Mon, 05 Dec 2005 21:32:17 +0100 Message-ID: References: <1bh3p11kcftnc9rtrhfihqc7r2olhe2oqj@4ax.com> <%JNkf.12425$lh.1687@tornado.ohiordc.rr.com> On Mon, 05 Dec 2005 02:37:47 GMT, "Wayne P. Muckleroy" wrote: >Did you also receive a calibration kit with the VNA? Nope. > If you did so, then the >lengths of these interconnect cables are not crucial for calibrated >measurements. Only uncalibrated measurements will be affected. > >It would help to know the manufacturer and model of the VNA. It's a good old HP 8754A -- "What is now proved was once only imagin'd" - William Blake Article: 219799 of rec.radio.amateur.antenna From: Michael Coslo Subject: Re: dipole and balun question Date: Mon, 05 Dec 2005 16:40:14 -0500 Message-ID: References: <%e0lf.43999$i7.18434@bignews2.bellsouth.net> RB wrote: > Some questions about a 140' dipole fed with ladderline from an unbalanced > tuner to work 160-10m: > > 1. Does it matter if the balun is placed on the tuner output, or at the > dipole center feedpoint? Run the ladder line directly into the feedpoint from the tuner. The balun is in your tuner. > 2. Which type of balun (voltage/current) would be best for > centerfeedpoint > use? > 4. What ratio balun would be optimal for either application? The one in your tuner will suffice. - 73 de Mike KB3EIA - Article: 219800 of rec.radio.amateur.antenna Message-ID: <4394B58C.5DFAB8E9@shaw.ca> From: Irv Finkleman Subject: Re: What is a duplexer, diplexer and combiner? References: Date: Mon, 05 Dec 2005 21:47:53 GMT Steve Nosko wrote: > > "crb" wrote in message news:dn09hk02r2p@enews1.newsguy.com... > > What are the functions of each of these? > > > > Are they used on TX or RX circuits? > > > > I know a cell site uses a duplexer so that it > > has an extra RX antenna for diversity. How > > does this work? Is the duplexer on the antenna > > that transmit/receive combo antenna notching > > out the TX frequency so the receiver doesn't get > > overloaded by it? > > Crb, > > These are basically filters. The terminology varies sometimes > for "diplexer" and "duplexer", and they are both used to describe the same > or different things. I'll give the way they are used in my field - two-way > radio and cell phone systems. > (Snipped for Brevity) > > Hope this helps. > > 73, Steve, K,9.D;C'I Nice answer Steve! I learned a few things myself! Irv VE6BP -- -------------------------------------- Diagnosed Type II Diabetes March 5 2001 Beating it with diet and exercise! 297/215/210 (to be revised lower) 58"/43"(!)/44" (already lower too!) -------------------------------------- Visit my HomePage at http://members.shaw.ca/finkirv/index.html Visit my Baby Sofia website at http://members.shaw.ca/finkirv4/index.htm Visit my OLDTIMERS website at http://members.shaw.ca/finkirv5/index.htm -------------------- Irv Finkleman, Grampa/Ex-Navy/Old Fart/Ham Radio VE6BP Calgary, Alberta, Canada Article: 219801 of rec.radio.amateur.antenna From: Owen Duffy Subject: Re: My vertical blew down!!! Message-ID: References: <1133576906.890685.201870@g47g2000cwa.googlegroups.com> <84rkf.28413$Gd6.6054@pd7tw3no> <1133659754.412000.285590@z14g2000cwz.googlegroups.com> <1133771837.159058.96930@g44g2000cwa.googlegroups.com> <1133818511.007393.138960@g49g2000cwa.googlegroups.com> Date: Mon, 05 Dec 2005 21:48:21 GMT On 5 Dec 2005 13:35:11 -0800, eternalsquire@comcast.net wrote: >I have one problem... I can only get stuff from Home Depot, about 50 >miles away. You received some good detailed advice, and dismiss it because it isn't on the shelf at Home Depot (whoever they are, presumably a major hardware chain that has squeezed competition out of the market place). Gee, I can get stuff from DX Engineering and a whole lot of other US based suppliers, and I am ~ 10,000 miles away. Think positively, go find some solutions, select the best and implement it. Owen -- Article: 219802 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: My vertical blew down!!! References: <1133576906.890685.201870@g47g2000cwa.googlegroups.com> <84rkf.28413$Gd6.6054@pd7tw3no> <1133659754.412000.285590@z14g2000cwz.googlegroups.com> <1133771837.159058.96930@g44g2000cwa.googlegroups.com> <1133818511.007393.138960@g49g2000cwa.googlegroups.com> Message-ID: Date: Mon, 05 Dec 2005 21:56:23 GMT eternalsquire@comcast.net wrote: > I have one problem... I can only get stuff from Home Depot, about 50 > miles away. If you don't have access to ordering over the internet, how are you posting to this newsgroup? -- 73, Cecil http://www.qsl.net/w5dxp Article: 219803 of rec.radio.amateur.antenna From: Michael Coslo Subject: Re: My vertical blew down!!! Date: Mon, 05 Dec 2005 17:01:01 -0500 Message-ID: References: <1133576906.890685.201870@g47g2000cwa.googlegroups.com> <84rkf.28413$Gd6.6054@pd7tw3no> <1133659754.412000.285590@z14g2000cwz.googlegroups.com> <1133818434.129752.268340@g44g2000cwa.googlegroups.com> eternalsquire@comcast.net wrote: > I have no trees, streelamps, telephone poles, or anything higher than a > 7 foot trailer. That was why I was considering a vertical. For > practical purposes anything higher than 40 feet is forbidden and 25 > foot is as high as I practically dare do. Vertical is probably the way to go for you. > From what I understand, > dipoles are not effective below 1/2 wavelength above the dirt, Almost true. The (misnamed?) takeoff angle of a vertical antenna is usually lower than a dipole that is lower than optimum. However, if the vertical is not terribly efficient, it may not work as well as a dipole that is more efficient. That is Why I think TOA is a misnomer. Antennas radiate in all directions. It's just that the signal strength is higher or lower at certain angles. > but > verticals can work well fairly close to the dirt if they have to. From > what I hear inverted vees are slightly better than dipoles but slightly > worse than verticals at low altitude. Well, they are a little different anyway. > My wife really doesn't care about money as much as she cares about > waste. If I can make my setup working with the stuff I already bought > then great... At this point I am considering just throwing in the towel > and raising a 20 foot iron pipe to mount a 20 meter inverted vee... > sigh. > 20m is my favorite band, followed by 40 then 30. I think I'd be making that V right about now. - 73 de Mike KB3EIA - Article: 219804 of rec.radio.amateur.antenna From: Gene Fuller Subject: Re: Antenna reception theory References: <7955-43907316-416@storefull-3256.bay.webtv.net> <11p322i7mfa917d@corp.supernews.com> <11p4qke5i7jv82b@corp.supernews.com> <11p54qa720fpf1b@corp.supernews.com> <11p5blcru430q9d@corp.supernews.com> <7YPkf.26664$dO2.972@newssvr29.news.prodigy.net> <020lf.125287$qk4.90216@bgtnsc05-news.ops.worldnet.att.net> Message-ID: Date: Mon, 05 Dec 2005 22:19:37 GMT Cecil, If this is name-dropping poker, I'll see your Hecht and raise with J.D. Jackson and Born & Wolf. But thanks for the education. After 40 years of obtaining multiple degrees in physics followed by working R&D in the optics field I guess I still need to seek out some "real-world physicists" to figure out that energy is indeed something to "worry about". I never would have imagined such a thing! 73, Gene W4SZ Cecil Moore wrote: > Gene Fuller wrote: > >> Yes, most people with rudimentary arithmetic skills would agree that >> 75 plus 8.33 does not equal 133.33. > > > Too bad Dr. Best posted the equation: "Ptotal = 75w + 8.33w = 133.33w" > on this newsgroup (and, thank goodness, left it out of his article) so > he obviously disagreed with you at the time. He also said that interference > had nothing to do with it. > >> However, anyone even remotely familiar with waves would readily >> understand that the component waves Cecil loves to talk about are >> merely mathematical conveniences. It is entire possible to set up >> other model configurations, such as a combination of a one traveling >> wave and one standing wave. > > > What happens at an impedance discontinuity given those circumstances? To > find out, read my WorldRadio article, Part I of which is posted on my web > page. Part II will be posted after Christmas. At the risk of raising your > politically incorrect ire as I have done with this technical posting, > MERRY CHRISTMAS!. > >> In order to make his model work, Cecil needs to invoke the mythical P3 >> and P4 on the source side of the reflection discontinuity. He never >> gets around to explaining how these two waves, which exactly cancel at >> all points in space and at all times, can contain any energy at all. > > > The answer is simple. Do waves contain any energy at all? Do waves that > cancel contain any energy? If waves contain no energy, they cannot exist, > and therefore are incapable of canceling. If they exist and cancel, they > contained energy just before their cancellation. Any way you cut it, > my approach is consistent with the laws of physics as enumerated in > "Optics", > by Hecht, and yours leads to a contradiction of those laws of physics. > >> The reason that most practitioners of wave models solve for the fields >> first and then worry about power or energy is: >> >> a - This procedure works correctly all the time. > > > Yes, it does. But optics engineers didn't have the luxury of dealing > with voltages and currents. They had to solve the problem using powers. > And they did exactly that decades ago. That RF engineers refuse to > consider the laws of physics concerning EM waves developed by optics > engineers is absolutely astounding to me. W7EL put it best, something > to the effect that if it wasn't invented here, we don't want to hear it > (even if it is right). But I daresay that Eugene Hecht knows much more > about EM waves that you will ever know, given your closed mind. > >> I do not expect to change Cecil's mind. Other than his own potential >> embarrassment from the silly publications in World Radio, his folly is >> harmless. > > > You are just displaying your extreme ignorance, Gene. My "WorldRadio" > article > corrects some of the *conceptual* errors in Dr. Best's QEX article but > otherwise > contains the same equations as his article. If you disagree with me, you > are > also disagreeing with Dr. Best's equations, i.e. you are between a rock > and a > hard place. > > It is interesting that the very people who tell us not to worry about > energy > are the people who get so emotionally rabid when someone chooses to > worry about > energy like real-world physicists do. What do they possibly have to lose > besides > face, self-esteem, sleep, and their pseudo-religious guru status? :-) Article: 219805 of rec.radio.amateur.antenna From: Gene Fuller Subject: Re: Antenna reception theory References: <25147-43949744-445@storefull-3258.bay.webtv.net> Message-ID: Date: Mon, 05 Dec 2005 22:25:51 GMT Richard, OK, I will turn this right back at you. How do you know that the countless Faraday screens remove the E-field component from electromagnetic waves? "Saying it does not make it so." Yes, I understand they are used in broadcast transmission lines, and yes, I understand they take many lightning hits. Faraday screens are effective. How do you know that they also negate the fundamental properties of time-varying electric and magnetic fields as expressed by Maxwell's equations? 73, Gene W4SZ Richard Harrison wrote: > Gene, W4SZ write: > "As has been said many times on this newsgroup, it is not possible to > filter out one field component or the other." > > Saying it does not make it so. > > Countless Faraday screens are at work removing the E-field component > from electromagnetic waves. Faraday said that the voltage in a coupled > circuit depends only on the rate of change of the magnetic flux through > the circuit. He was refering to induced voltage. It was 1831 when > Michael Faraday observed the interaction between primary and secondary > coils in what was likely the world`s first transformer. Faraday made it > himself and noted that the needle of a galvanometer connected across one > coil deflected briefly whenever he connected or disconnected a battery > across the other coil. > Article: 219806 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Antenna reception theory References: <7955-43907316-416@storefull-3256.bay.webtv.net> <11p322i7mfa917d@corp.supernews.com> <11p4qke5i7jv82b@corp.supernews.com> <11p54qa720fpf1b@corp.supernews.com> <11p5blcru430q9d@corp.supernews.com> <7YPkf.26664$dO2.972@newssvr29.news.prodigy.net> <020lf.125287$qk4.90216@bgtnsc05-news.ops.worldnet.att.net> Message-ID: Date: Mon, 05 Dec 2005 22:42:58 GMT Gene Fuller wrote: > If this is name-dropping poker, I'll see your Hecht and raise with J.D. > Jackson and Born & Wolf. Please post any contradiction of Hecht by your sources. That argument could get very interesting. To summarize: Constructive interference energy must come from somewhere in the real world. You seem to disagree. So where do you think constructive interference energy comes from? > But thanks for the education. After 40 years of obtaining multiple > degrees in physics followed by working R&D in the optics field ... If you are omniscient, please prove it. If you are not omniscient and still capable of learning, please admit it. The trouble with gurus is that they sincerely believe that they know everything already and therefore cannot possibly learn anything new. I'm still open to learning. How about you? > ... I guess I > still need to seek out some "real-world physicists" to figure out that > energy is indeed something to "worry about". I never would have imagined > such a thing! That's a really strange thing to admit, Gene, since a very large percentage of the physics community is dedicated to understanding where the energy was, is, and will be - down to an almost infinitessimally small amount. You definitely seem to be cast in the mold of the priests who put Galileo under house arrest. Are you comfortable with that position? -- 73, Cecil http://www.qsl.net/w5dxp Article: 219807 of rec.radio.amateur.antenna From: Gene Fuller Subject: Re: Antenna reception theory References: <7955-43907316-416@storefull-3256.bay.webtv.net> <11p322i7mfa917d@corp.supernews.com> <11p4qke5i7jv82b@corp.supernews.com> <11p54qa720fpf1b@corp.supernews.com> <11p5blcru430q9d@corp.supernews.com> <7YPkf.26664$dO2.972@newssvr29.news.prodigy.net> <020lf.125287$qk4.90216@bgtnsc05-news.ops.worldnet.att.net> Message-ID: <0t3lf.230043$zb5.115797@bgtnsc04-news.ops.worldnet.att.net> Date: Mon, 05 Dec 2005 22:48:28 GMT Cecil, If you know anything about physics, you must know that energy is at the core of almost all physical analysis. Sorry that my message was too opaque for you. 73, Gene W4SZ Cecil Moore wrote: > Gene Fuller wrote: > > >> ... I guess I still need to seek out some "real-world physicists" to >> figure out that energy is indeed something to "worry about". I never >> would have imagined such a thing! > > > That's a really strange thing to admit, Gene, since a very large percentage > of the physics community is dedicated to understanding where the energy > was, is, and will be - down to an almost infinitessimally small amount. > You definitely seem to be cast in the mold of the priests who put Galileo > under house arrest. Are you comfortable with that position? Article: 219808 of rec.radio.amateur.antenna From: Roy Lewallen Subject: Re: Antenna reception theory Date: Mon, 05 Dec 2005 14:50:27 -0800 Message-ID: <11p9h1kn73bctd4@corp.supernews.com> References: <25147-43949BCA-447@storefull-3258.bay.webtv.net> A short while ago, I explained why your Faraday cage doesn't separate E and H as you claim. Exactly the same explanation applies to this structure, but with E and H reversed. It locally modifies the E/H ratio but doesn't separate the field components and it certainly doesn't remove the E field as you claim. Roy Lewallen, W7EL Richard Harrison wrote: > it is just as easy to remove the H-field from the wave as it is to > remove the E-field with a Faraday screen. > > To remove the H-field, one sure way is to completely enclose two coils > so they are completely shielded from each other and all electromagnetic > waves. Put the coils in separate metal cans. Put a tiny hole in each > can. Conect one termial of each coil to its end of a coupling capcitor. > Ground the other terminal of each coil.. Ground is the return path for > the coils but it must run on the surfaces of the cans and through the > tiny holes due to skin effect. > Complete shielding removes the H-field as a coupling agent. Only E-field > coupling is provided via the coupling capacitor. > > Best regards, Richard Harrison, KB5WZI > Article: 219809 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Antenna reception theory References: <7955-43907316-416@storefull-3256.bay.webtv.net> <11p322i7mfa917d@corp.supernews.com> <11p4qke5i7jv82b@corp.supernews.com> <11p54qa720fpf1b@corp.supernews.com> <11p5blcru430q9d@corp.supernews.com> <7YPkf.26664$dO2.972@newssvr29.news.prodigy.net> <020lf.125287$qk4.90216@bgtnsc05-news.ops.worldnet.att.net> <0t3lf.230043$zb5.115797@bgtnsc04-news.ops.worldnet.att.net> Message-ID: Date: Mon, 05 Dec 2005 22:56:06 GMT Gene Fuller wrote: > If you know anything about physics, you must know that energy is at the > core of almost all physical analysis. I couldn't agree more, but that's exactly the topic from which you tried to divert attention in your posting. Here's what you said: >"I guess I still need to seek out some "real-world physicists" to > figure out that energy is indeed something to "worry about". I > never would have imagined such a thing!" If you don't worry about energy, you have nothing to add to the discussion. If you do worry about energy, please read my "WorldRadio" article which tells you more than you (and others) ever wanted to know about energy in an RF transmission line. -- 73, Cecil http://www.qsl.net/w5dxp Article: 219810 of rec.radio.amateur.antenna From: "RB" References: <%e0lf.43999$i7.18434@bignews2.bellsouth.net> Subject: Re: dipole and balun question Message-ID: Date: Mon, 5 Dec 2005 19:32:03 -0600 Fell prey to the old "don't engage mouth prior to engaging brain" syndrome. Sorry about the confusion I caused. My bad. Was just wondering if coax feed with balun at centerpoint would be better than ladderline feed with balun at tuner output (and no, my tuner doesn't have an internal balun). Article: 219811 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: dipole and balun question References: <%e0lf.43999$i7.18434@bignews2.bellsouth.net> Message-ID: Date: Tue, 06 Dec 2005 01:49:43 GMT RB wrote: > Was just wondering if coax feed with balun at centerpoint would be better > than ladderline feed with balun at tuner output. You could probably get away with 2" hardline at about $10 a foot if cost is not object. -- 73, Cecil http://www.qsl.net/w5dxp Article: 219812 of rec.radio.amateur.antenna From: Owen Duffy Subject: Re: dipole and balun question Message-ID: References: <%e0lf.43999$i7.18434@bignews2.bellsouth.net> Date: Tue, 06 Dec 2005 01:56:19 GMT On Mon, 5 Dec 2005 19:32:03 -0600, "RB" wrote: >Was just wondering if coax feed with balun at centerpoint would be better >than ladderline feed with balun at tuner output (and no, my tuner doesn't >have an internal balun). I can only assume that if you are still asking that question 6 hours after I wrote you a response, that you didn't read / understand the response and the referenced article! If that was too hard to understand, the short answer is NO. If you want to understand why, go back and read my earlier posting and the article. Owen -- Article: 219813 of rec.radio.amateur.antenna From: Gene Fuller Subject: Re: Antenna reception theory References: <7955-43907316-416@storefull-3256.bay.webtv.net> <11p322i7mfa917d@corp.supernews.com> <11p4qke5i7jv82b@corp.supernews.com> <11p54qa720fpf1b@corp.supernews.com> <11p5blcru430q9d@corp.supernews.com> <7YPkf.26664$dO2.972@newssvr29.news.prodigy.net> <020lf.125287$qk4.90216@bgtnsc05-news.ops.worldnet.att.net> <0t3lf.230043$zb5.115797@bgtnsc04-news.ops.worldnet.att.net> Message-ID: Date: Tue, 06 Dec 2005 02:08:42 GMT Cecil, Sorry, I should have written, "I guess I still need to seek out some "real-world physicists" to figure out that energy is indeed something to "worry about". I never would have imagined such a thing!" 8-) 8-) 8-) 8-) 8-) 8-) 8-) 8-) 8-) 8-) 8-) 8-) 8-) 8-) 8-) 8-) 8-) 8-) I thought my intention was obvious, but it seems I failed to communicate. 73, Gene W4SZ Cecil Moore wrote: > Gene Fuller wrote: > >> If you know anything about physics, you must know that energy is at >> the core of almost all physical analysis. > > > I couldn't agree more, but that's exactly the topic from which you tried > to divert attention in your posting. Here's what you said: > > >"I guess I still need to seek out some "real-world physicists" to > > figure out that energy is indeed something to "worry about". I > > never would have imagined such a thing!" > > If you don't worry about energy, you have nothing to add to the discussion. > If you do worry about energy, please read my "WorldRadio" article which > tells you more than you (and others) ever wanted to know about energy in an > RF transmission line. Article: 219814 of rec.radio.amateur.antenna From: richardharrison@webtv.net (Richard Harrison) Subject: Re: Antenna reception theory Date: Mon, 5 Dec 2005 21:11:18 -0600 Message-ID: <13800-43950156-464@storefull-3254.bay.webtv.net> References: <11p9h1kn73bctd4@corp.supernews.com> Roy Lewallen, W7EL wrote: "A short while ago, I explained why your Faraday cage doesn`t separate the E and H fields as you claim." n I am misunderstood. I never used the tem Faraday cage. I understand the Faraday cage to be a completely shielded enclosure which could be a metal automobiole body, a steel rebar reinforced concrete structure or a screened room. These all tend to completely block both the E-field and the H-field components of an electromagnetic wave. I gave an example of the metal rakes (Faraday screens) used at the medium wave broadcast plants where I worked. The function of the Faraday screen was primarily to eliminate capacitive cooupling, and thus the E-field between the transmission line and the antenna. This reduces harmonic radiation. It adds expense and complexity but is worth the price for lightning suppression if for nothing else. Most Faraday screens are used at powerline frequencies to eliminate capaacitive coupling between primary and secondary of a power transformer. I checked the internet for a recent posting and found an article by arnie@radiohc.org who wrote: "Beware, this cannot be an auto-transformer. It must be a transformer with two completely isolated windings, and with a Faraday Screen wound between the two." Why would one pay a lot of extra money for a transformer which eliminated capacitive coupling if it didn`t work, especially in Havana, Cuba? Best regards, Richard Harrison, KB5WZI Article: 219815 of rec.radio.amateur.antenna From: richardharrison@webtv.net (Richard Harrison) Subject: Re: Antenna reception theory Date: Mon, 5 Dec 2005 22:36:29 -0600 Message-ID: <7954-4395154D-2385@storefull-3256.bay.webtv.net> References: Gene, W4SZ wrote: "How do you know that they also negate the fundamental properties of time-varing electric and magnetic fields as expressed by Maxwell`s equations?" I did not make that claim. Pits from the lightning strikes are evidence that the voltage gradient is high between the coil and the Faraday screen. The second coil is clean, not pitted. I explained the operation of a Faraday screen earlier but was misunderstood so I`ll quote a professional writer and consulting engineer, B. Whitfield Griffith, Jr. who writes on page 246 of "Radio-Electronic Transmission Fundamentals": "It is often desirable and practical to allow one type of coupling between circuits and eliminate the other. Figure 28-1, for instance, shows two coils which are coupled but have a special type of shielding between them that causes the coupling to be purely inductive and not capacitive, This shield consists of an array of parallel wires which are grounded at one end only. The lines of electric force from the coils terminate on these grounded wires, so that there are no electric lines of force passing from one coil to the other and hence no capacitive coupling. On the other hand, since the wires do not form closed loops, there is no circulating current in the shield and therefore nothing to stop the penetration of the shield by the magnetic field. This type of shield has long been known as a Faraday screen. It is important that the capacitive coupling be eliminated in many cases, since it has the characteristics of a high-pass filter, tending to accentuate the harmonic content of the transmitted signal." I never tried it, but I`d bet that someone has measured the radiated harmonics both with and without the Faraday screens inplace. That would prove effectiveness. Short-circuiting the open ends of the Faraday screen wires would kill transfer of the signal between primary and secondary of the transformer, and the transmitter would likely complain. Best regards, Richard Harrison, KB5WZI Article: 219816 of rec.radio.amateur.antenna From: "W. Watson" Subject: Re: C. Crane's Twin Ferrite Antenna References: <438e802d@nntp.zianet.com> <8Kzjf.84363$QM5.38523@tornado.socal.rr.com> Message-ID: Date: Tue, 06 Dec 2005 05:19:12 GMT Ken Fowler wrote: > On 1-Dec-2005, Phil Wheeler wrote: > > >>Xref: number1.nntp.dca.giganews.com rec.radio.amateur.antenna:253561 >> >>BKR wrote: >> >>>Computers and computer components are regulated by the FCC. >>>They MUST NOT cause interferance to licenced radio services. >>>(like the radio stations you are trying to tune in.) >>>Make that clear to the vendor you got the power supply from! >>> >> >>Interesting thought but impractical. It could be the installation >>(e.g., grounding) vs. the supply itself. Event if the PSU itself, >>proving it would be a chore. > > > The noise from PC Power Supplies is usually radiated from the power cord and the house wiring. The > cause is often that the manufacturers cut cost by leaving out the L and C components of the line > filter. Usually you will find the place on the PSU circuit board to mount a bi-filar choke and two > or three capacitors. The capacitors are missing and the pads for the choke are jumpered. If you > can find an older junk PSU which has the components, just unsolder them from the junk board and > install them in your PSU. Sometimes the PSU's in Monitors have the filter components. > > When I installed the filter in my old Pentium, the switch mode hash on broadcast band stations went > down by 30 db. Installing line filters outside the CPU Case had very little effect. > > -ken- I was in the HSC store in Sacramento and discovered some filters that were inside the AC switch. I decided against them, since I wasn't sure about the amperage. I would think though the chassis builder might include such devices, but haven't checked. Tomorrow I'll order the corcom filter 10ek7 10 amps that someone suggested from a place in San Jose, CA. $5.00. I'll give that a whirl. Looks like I'll have to cut the cord to put it in the line. -- Wayne T. Watson (Watson Adventures, Prop., Nevada City, CA) (121.015 Deg. W, 39.262 Deg. N) GMT-8 hr std. time) Obz Site: 39° 15' 7" N, 121° 2' 32" W, 2700 feet Traveling in arid or desert country? Check your boots well to see if you have a scorpion in them. -- Survivorman, Discovery (SCI) Channel Web Page: Article: 219817 of rec.radio.amateur.antenna From: Roy Lewallen Subject: Re: Antenna reception theory Date: Mon, 05 Dec 2005 21:53:33 -0800 Message-ID: <11pa9quedgve336@corp.supernews.com> References: <11p9h1kn73bctd4@corp.supernews.com> <13800-43950156-464@storefull-3254.bay.webtv.net> *Sigh* Richard Harrison wrote: > Roy Lewallen, W7EL wrote: "A short while ago, I explained why your > Faraday cage doesn`t separate the E and H fields as you claim." n I > am misunderstood. I never used the tem Faraday cage. I understand the > Faraday cage to be a completely shielded enclosure which could be a > metal automobiole body, a steel rebar reinforced concrete structure > or a screened room. These all tend to completely block both the > E-field and the H-field components of an electromagnetic wave. Sorry, I meant "Faraday screen", which is the term you used, and I used in my posting explaining its operation. If you block either the E or H field, you also block the other. You can't independently block one or the other. > . . . > Why would one pay a lot of extra money for a transformer which > eliminated capacitive coupling if it didn`t work, especially in > Havana, Cuba? Because in order to "work" it doesn't need to "eliminate capacitive coupling". All it needs to do is locally reduce the E/H field ratio, which is what it does. Roy Lewallen, W7EL Article: 219818 of rec.radio.amateur.antenna From: HS Subject: Re: My vertical blew down!!! References: <1133576906.890685.201870@g47g2000cwa.googlegroups.com> <9cffe$43911003$97d56a33$7851@ALLTEL.NET> <1133584284.471704.259160@g49g2000cwa.googlegroups.com> Message-ID: Date: Tue, 06 Dec 2005 10:55:26 GMT My suggestion would be the following: Cut that buried 1" pipe about a foot over the ground, to serve as a ground support for your new antenna. Get a heavier steel pipe (ca 1"3/4 - 2") that will fit over the 1" pipe, and perhaps 10 foot long. Get a cheap fiberglass (not carbon) fishing rod ca 18 feet long, (1/4 wave on 20m) Tape a 1/4 wire radiator to the fishing rod, and feed with coax at bottom of rod. Attach fishing rod securely to the top of your new mast pipe. Rise the pipe and fishing rod assembly vertically and guy at the point where the fishing rod is attached. Now you can run elevated wire radials along the guy ropes, and you should probably also ground the coax shield to the mast pipe at the feed point. Enjoy! 73 de Hans, SM3PXG eternalsquire@comcast.net wrote: > Ground system: > > 5 foot of 1 inch diameter galvanized iron pipe, halfway stuck in ground > with concrete. > 9 foot carbon fiber fishing rod, handle epoxied and inserted into pipe > a wire is attached to copper pipe and run up to end of rod. > Hot end of coax connected to bottom of copper pipe > > > Rope guys are econnected to the top part of the shaft coupler, as the > middle of the shaft coupler is predicted to be weakest point. > > > Sigh, > > The Eternal Squire > Article: 219819 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Antenna reception theory References: <7955-43907316-416@storefull-3256.bay.webtv.net> <11p322i7mfa917d@corp.supernews.com> <11p4qke5i7jv82b@corp.supernews.com> <11p54qa720fpf1b@corp.supernews.com> <11p5blcru430q9d@corp.supernews.com> <7YPkf.26664$dO2.972@newssvr29.news.prodigy.net> <020lf.125287$qk4.90216@bgtnsc05-news.ops.worldnet.att.net> <0t3lf.230043$zb5.115797@bgtnsc04-news.ops.worldnet.att.net> Message-ID: <1yglf.32224$Zv5.9900@newssvr25.news.prodigy.net> Date: Tue, 06 Dec 2005 13:41:17 GMT Gene Fuller wrote: > I thought my intention was obvious, but it seems I failed to communicate. Others on this newsgroup have admonished me for worrying about energy and refused to discuss the subject. I thought you were doing the same. Sorry. But do you actually have any references that contradict "Optics", by Hecht? In Dr. Best's article, he superposes V1 with V2 such that constructive interference energy is needed to complete the superposition. On this newsgroup, I asked Dr. Best where that necessary constructive interference energy comes from and he didn't know. That's when I went searching for references and found them in the field of optics. Constructive interference energy can be supplied by local sources as occurs in W7EL's "Food for Thought #1" with its DC example. Or constructive interference energy can be supplied at a point away >from the source(s) by destructive interference, e.g. wave cancellation at the non-reflection surface of a layer of thin-film on glass or at a match point in a transmission line. -- 73, Cecil http://www.qsl.net/w5dxp Article: 219820 of rec.radio.amateur.antenna From: "Jeff Dieterle" Subject: Re: Am Antenna Help Date: Tue, 6 Dec 2005 08:55:54 -0500 Message-ID: <11pb63eng0i06fb@corp.supernews.com> References: <11oos4qo1fo1dd2@corp.supernews.com> <11orh6rkdfkqj6a@corp.supernews.com> <11otv7q7vq0a450@corp.supernews.com> "John S. Dyson" wrote in message news:dmspa6$srh$1@news.iquest.net... > In article <11otv7q7vq0a450@corp.supernews.com>, > "Jeff Dieterle" writes: >>>>> You never mention how far away you are from "... Indianapolis 1070kc >>>>> and >>>>> Chicago 670kc & 1000kc." That'll have a LARGE bearing on the >>>>> day/night >>>>> reception question. >>>>> >>>>> Jonesy >>>>> -- >>>>> Marvin L Jones | jonz | W3DHJ | linux >>>>> Pueblo, Colorado | @ | Jonesy | OS/2 __ >>>>> 38.24N 104.55W | config.com | DM78rf | SK >> >> I'm 70mi from Indy and 120mi from Chicago. Chicago 670kc is reasonable at >> night 1070kc out of Indy at night is pretty bad. >> Is 40ft at right angles to these signals better that 200ft parallel? >> > (This doesn't solve your problem, but might give you some info as to > why the reception of WIBC is somewhat difficult.) > > Given your distances, then you are somewhere between Indy and Chicago. > > WIBC drops their power significantly at night, and also the antenna > pattern shows that the available signal is probably the worst possible > given the antenna :-(. Here is a picture of the WIBC pattern, and > consider the WIBC towers are on the NW side of Indy. > > http://www.fcc.gov/Bureaus/MB/Databases/AM_DA_patterns/306964-6786.pdf > > John Ya, I see they drop their signal strength from 50kw to 10kw at night. What would be the best antenna design for this station. I've considered buying a tuned loop for this frequency but I'm reluctant to drop $70 and maybe not do any better than my straightwire. Article: 219821 of rec.radio.amateur.antenna From: Eskay Subject: Re: dipole and balun question References: <%e0lf.43999$i7.18434@bignews2.bellsouth.net> Message-ID: <6z1e3q30df0a.18pnjpqbo6wpx$.dlg@40tude.net> Date: Tue, 06 Dec 2005 14:05:19 GMT On Tue, 06 Dec 2005 01:56:19 GMT, Owen Duffy wrote: > On Mon, 5 Dec 2005 19:32:03 -0600, "RB" > wrote: > > >>Was just wondering if coax feed with balun at centerpoint would be better >>than ladderline feed with balun at tuner output (and no, my tuner doesn't >>have an internal balun). > > I can only assume that if you are still asking that question 6 hours > after I wrote you a response, that you didn't read / understand the > response and the referenced article! > > If that was too hard to understand, the short answer is NO. If you > want to understand why, go back and read my earlier posting and the > article. > > Owen There is now a certain amount of sarcasm flowing in this thread. The HAM spirit died. Pity. Eskay. Article: 219822 of rec.radio.amateur.antenna From: "Frank" References: <3M-dnWU27IqxggjenZ2dnUVZ_sydnZ2d@comcast.com> Subject: Re: measuring antenna resonance with an 8405a Message-ID: Date: Tue, 06 Dec 2005 14:28:41 GMT >I would like to know if the follow technique will work to measure resonance >of an antenna. I know have a working HP 8405a. It has been a struggle to >repair it and to align it, however it now appears to be working. > > My plan is to connect a bi-directional coupler to the 8405a. The coupler > will be terminated in a 50 Ohm terminator. The phase will be read for this > configuration. The next step is to replace the 50 Ohm terminator with a > direct connection to an unknown antenna. I will then change the frequency > until the phase angle matchs the 50 Ohm phase angle. > > Does this make sense? > > What are the draw backs? > > How close will this method get compared to a noise bridge? > > Thanks - Dan kb0qil Dan, the phase angle of the reflection coefficient of a matched load is unimportant, and is likely to be anything. Specifically; if it is a dot on the Smith Chart center -- who cares? Typically the return loss of a good quality load could well be > 40dB. Again, if you are measuring beyond the frequency range of the coupler you must determine its directivity. It is very likely that you are reading the phase of poor directivity and not the 50 ohm load. Also if you are using the 8405A, do you have all the accessories? In particular the BNC ( + 50 ohm thru) probe attachments which should be connected directly to your coupler ports. If you require N - BNC adapters to connect to the coupler, then as long as you have the same structures on each port, any phase error will be cancelled out. It is also good practice to attach a high quality 20 dB pad to the input of the coupler (thus ensuring your source return loss approaches 40 dB) -- you cannot always be certain that your source, plus coax, provides a good match. Note if the unit cannot lock with the 20 dB pad, then at least use a 10 dB pad. Another test is to connect both probes to the same source via a BNC "T" adapter. Do you show zero phase error? Interesting you have an 8405A, it is many years since I used one. I see them priced from $250.00 to a fully refurbished unit from Tucker (www.tucker.com) for $2,500.00. Regards, Frank Article: 219823 of rec.radio.amateur.antenna From: Bob Miller Subject: Re: dipole and balun question Message-ID: References: <%e0lf.43999$i7.18434@bignews2.bellsouth.net> <__0lf.44003$i7.4483@bignews2.bellsouth.net> Date: Tue, 06 Dec 2005 14:37:27 GMT On Mon, 5 Dec 2005 14:02:03 -0600, "RB" wrote: >Oooopss----I meant coax fed. > If you're really going to feed the antenna with coax, why do you need a balun? Just run the coax straight to your tuner coax connection. You're losses on various bands may be pretty high with coax. That's why most all-banders are fed with ladderline. Losses are lower. But that's your choice. Bob k5qwg Article: 219824 of rec.radio.amateur.antenna From: Michael Coslo Subject: Re: dipole and balun question Date: Tue, 06 Dec 2005 09:45:27 -0500 Message-ID: References: <%e0lf.43999$i7.18434@bignews2.bellsouth.net> RB wrote: > Fell prey to the old "don't engage mouth prior to engaging brain" syndrome. > > Sorry about the confusion I caused. My bad. > > Was just wondering if coax feed with balun at centerpoint would be better > than ladderline feed with balun at tuner output (and no, my tuner doesn't > have an internal balun). Didn't you say you had an unbalanced tuner? Most modern ones have a balun to perform that function. I suspect there is one in there. I have been toying with an "old school unbalanced one that uses a couple roller inductors, but I haven't seen too many of those around. At any rate, if you put up 140 feet of dipole, and want to work 160-10 meters, you *should* be using balanced line, and a tuner that can handle that. Trying to use a coax fed system and tuner in this manner, you'll not have very good luck. The coax will have problems at some of the very high mismatches at some frequencies. - 73 de Mike KB3EIA - Article: 219825 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: dipole and balun question References: <%e0lf.43999$i7.18434@bignews2.bellsouth.net> <__0lf.44003$i7.4483@bignews2.bellsouth.net> Message-ID: <4lilf.29254$q%.10093@newssvr12.news.prodigy.com> Date: Tue, 06 Dec 2005 15:44:00 GMT Bob Miller wrote: > You're losses on various bands may be pretty high with coax. That's > why most all-banders are fed with ladderline. Losses are lower. But > that's your choice. Owen has a feedline loss calculator at: http://www.vk1od.net/tl/tllce.php EZNEC (including the free demo version at www.eznec.com) can be used to estimate the SWR to plug into the calculator. For instance, 100 feet of RG-58a used on 14 MHz with an average SWR of 5:1, loses ~4.7 dB, or ~66%. To get the same loss with Wireman #554 ladder-line, the average SWR could be allowed to equal 53:1. -- 73, Cecil http://www.qsl.net/w5dxp Article: 219826 of rec.radio.amateur.antenna From: richardharrison@webtv.net (Richard Harrison) Subject: Re: Antenna reception theory Date: Tue, 6 Dec 2005 09:41:40 -0600 Message-ID: <13799-4395B134-1973@storefull-3254.bay.webtv.net> References: Richard Clark, KB7QHC wrote: "From your copy of Bailey, review the text, and reconcile his remarks." Richard Clarks advice is good. Arnold B. Bailey in "TV and Other Receiving Antennas" does a more extensive job of explaining how antennas work than most other authors. Wish everybody interested in antennas could read Bailey.His catalog of antenna types is convenient too. Best regards, Richard Harrison, KB5WZI Article: 219827 of rec.radio.amateur.antenna From: "W. Watson" Subject: Re: C. Crane's Twin Ferrite Antenna References: Message-ID: Date: Tue, 06 Dec 2005 16:34:30 GMT This is really weird. The noise stopped! There's no question that when I first noticed this some weeks ago that it was linked to turning the PC on, and would disappear when I turned it off. I haven't changed anything. -- Wayne T. Watson (Watson Adventures, Prop., Nevada City, CA) (121.015 Deg. W, 39.262 Deg. N) GMT-8 hr std. time) Obz Site: 39° 15' 7" N, 121° 2' 32" W, 2700 feet Traveling in arid or desert country? Check your boots well to see if you have a scorpion in them. -- Survivorman, Discovery (SCI) Channel Web Page: Article: 219828 of rec.radio.amateur.antenna From: richardharrison@webtv.net (Richard Harrison) Subject: Re: Antenna reception theory Date: Tue, 6 Dec 2005 10:21:57 -0600 Message-ID: <13801-4395BAA5-110@storefull-3254.bay.webtv.net> References: Dan Sawyeror wrote: "They can be created separately, that is a capacitor is pretty much a pure E field and an inductor an H field." Agreed. Whenever a current grows or shrinks (with acceleration) it produces both an E-field and an H-field. I didn`t clam a permanent divorce, only an instantaneous separation. Best regards, Richard Harrison, KB5WZI Article: 219829 of rec.radio.amateur.antenna From: "Frank" References: <3M-dnWU27IqxggjenZ2dnUVZ_sydnZ2d@comcast.com> Subject: Re: measuring antenna resonance with an 8405a Message-ID: Date: Tue, 06 Dec 2005 16:48:32 GMT >>Sort of, but not exactly. As I described in another thread, the >>pitfall is the fact that the phase lengths of the coupler are >>different. You could set the phase offset to zero at frequency X but >>when you change to frequency Y, there is a built-in error. > > I should have added that you don't do this with a 50 ohm load, but a > short circuit instead. You want a big reflection with a known phase > for a calibration standard. The first step is to establish the accuracy of the test equipment. A short/open at the output port of the directional coupler should produce a frequency independant phase shift between the forward and reverse coupled port. If you are not getting 180/0 deg, then there is something fundamentally wrong with the test set up. Connecting both probes of the 8405A to the same source should establish if any errors exist in the vector voltmeter. Using the BNC/probe adapters is essential to maintain repeatability in your measurements. Reference HP's 778D coupler at http://cp.literature.agilent.com/litweb/pdf/5952-8133.pdf : " Impedance Measurements The 778D is also well suited for measurements of impedance when used with the Agilent 8405A vector voltmeter. The technique is described in Application Note 77-3, Measurement of Complex Impedance, available at your nearest Agilent sales office. Again, a reflectometry technique is used. With the vector voltmeter, however, both magnitude and phase angle of the reflection coefficient can be measured. This setup is shown in Figure 3. Data can be read from the two meters of the vector voltmeter and transferred directly to a Smith Chart to provide impedance of such devices as antennas or other passive components. "It is many years since I have seen AN77-3, but I seem unable to find a copy on the web. Frank Article: 219830 of rec.radio.amateur.antenna From: "Joel Kolstad" Subject: Re: Antenna reception theory Date: Tue, 6 Dec 2005 09:28:55 -0800 Message-ID: <11pbil7r81dkk7e@corp.supernews.com> References: <13799-4395B134-1973@storefull-3254.bay.webtv.net> "Richard Harrison" wrote in message news:13799-4395B134-1973@storefull-3254.bay.webtv.net... > Richard Clarks advice is good. Arnold B. Bailey in "TV and Other > Receiving Antennas" does a more extensive job of explaining how antennas > work than most other authors. Wish everybody interested in antennas > could read Bailey.His catalog of antenna types is convenient too. It's out of print, but I've requested a copy through interlibrary loan. I'm curious to see what he has to say on the standard V-shaped rabbit ears that have been in use for decades... although one can readily simulate them and see exactly how they perform, I've yet to find anyone who had a good idea as to why rabbit ears haven't traditionally been oriented purely horizontally! Article: 219831 of rec.radio.amateur.antenna From: "Reg Edwards" Subject: Re: Antenna reception theory Date: Tue, 6 Dec 2005 17:28:42 +0000 (UTC) Message-ID: References: <11p9h1kn73bctd4@corp.supernews.com> <13800-43950156-464@storefull-3254.bay.webtv.net> <11pa9quedgve336@corp.supernews.com> "dansawyeror" wrote - > After reading this thread it seems there is significant confusion between E and > H fields created locally from electric current and the E and H aspects of a > passing RF photon stream. ======================================== When the geometric dimensions of the structures are short compared with a wavelength, the amps and volts are associated with the NEAR FIELD and Ohm's Law applies. The radiation field is so weak in comparison it can be forgotten about. KISS. Why does everybody HAVE to unnecessarily complicate matters in order to understand what really goes on? What have photons to do with winning a contest? ;o) ---- Reg. Article: 219832 of rec.radio.amateur.antenna From: "Steve Nosko" Subject: Re: What is a duplexer, diplexer and combiner? Date: Tue, 6 Dec 2005 10:43:21 -0600 Message-ID: References: <4394B58C.5DFAB8E9@shaw.ca> "Irv Finkleman" wrote in message news:4394B58C.5DFAB8E9@shaw.ca... > Steve Nosko wrote: > > > > "crb" wrote in message news:dn09hk02r2p@enews1.newsguy.com... > > > What are the functions of each of these? > > > [snippitty snip] > > Crb, > > > > These are basically filters. The terminology varies sometimes > > for "diplexer" and "duplexer", and they are both used to describe the same > > or different things. I'll give the way they are used in my field - two-way > > radio and cell phone systems. (Snipped for Brevity) > > 73, Steve, K,9.D;C'I > > Nice answer Steve! I learned a few things myself! > > Irv VE6BP Thanks Irv. Just what I hoped to accomplish. Because my brain is full and I am unable to get anything else in there, I am trying to get some empty space and at the same time pass along some of the knowledge I have gained over the many enjoyable years in Electronics. I do my best to get things down in a simple, understandable way. 73, Steve, K'9;D.C,I Article: 219833 of rec.radio.amateur.antenna From: "Steve Nosko" Subject: Re: dipole and balun question Date: Tue, 6 Dec 2005 11:26:40 -0600 Message-ID: References: <%e0lf.43999$i7.18434@bignews2.bellsouth.net> At the risk of starting something... Owen, I didn't see this point in your initial post. I've read a few of your posts and you seem to give pretty good explanations. I thought the answer would be that a wideband Balun (my assumption that the OP is referring to this type) of the type commonly used (Ferrite core & windings) is not recommended for a multi-band antenna where the impedances vary widely. These baluns, I thought, are suitable only for impedances near their design center. For example, a 1:1 balun works well in a 50-50 ohm, 50-75 ohm or 75-75 or 50-33 ohm system. A 4:1 (or perhaps more correctly 1:4) works ok with 50-200. 50-300, 50-133. Using a 1:1 between tuner and antenna (at either end of the feed line) when the antenna impedance may be 200 or 1000 ohms on some band, causes grief for the balun in the form of poor efficiency and possibly a burned up balun - because the balun is operating in a system impedance much different than this design center. These baluns are not suitable for a wide range of impedances. Do I need to change my brand of drink, or have I got a reasonable understanding? Owen, It is my understanding that (ignoring patterns and focusing initially on the antenna) using a dipole which is not resonant on one of the harmonically related ham bands ( I believe the original Windom-circa 1945 and G5RV are in this category) avoids the problem of matching to the very high impedance at the even overtones (a 40M dipole is two half waves on 20M and a high Z). Yes, using ladder line vs. coax helps with this greatly, but then you have this age old problem of the bal to unbal issue. This, of course, somewhat ignores feed line loss, but this is a first approximation focusing on the antenna initially - and I realize that ignoring feed line loss is not what you do when looking at the WHOLE system. . I'll have to read your referenced article more fully (next). (:-) 73, Steve, K,9.D;C'I P.S. For the beginners, A signal has a harmonic. A resonant object (antenna, crystal, resonator, filter, etc) has an overtone - which is a resonance, typically but not necessarily, harmonically related - frequently slightly off the harmonic due to strays. "Owen Duffy" wrote in message news:kpr9p15ucolcauav7ahdjqscudfhusgrr3@4ax.com... > On Mon, 5 Dec 2005 19:32:03 -0600, "RB" > wrote: > > > >Was just wondering if coax feed with balun at centerpoint would be better > >than ladderline feed with balun at tuner output (and no, my tuner doesn't > >have an internal balun). > > I can only assume that if you are still asking that question 6 hours > after I wrote you a response, that you didn't read / understand the > response and the referenced article! > > If that was too hard to understand, the short answer is NO. If you > want to understand why, go back and read my earlier posting and the > article. > > Owen > -- Article: 219834 of rec.radio.amateur.antenna From: Jim Kelley Subject: Re: Antenna reception theory Date: Tue, 06 Dec 2005 10:07:35 -0800 Message-ID: References: <11p9h1kn73bctd4@corp.supernews.com> <13800-43950156-464@storefull-3254.bay.webtv.net> <11pa9quedgve336@corp.supernews.com> Roy Lewallen wrote: > *Sigh* > > Richard Harrison wrote: > >> Roy Lewallen, W7EL wrote: "A short while ago, I explained why your >> Faraday cage doesn`t separate the E and H fields as you claim." n I >> am misunderstood. I never used the tem Faraday cage. I understand the >> Faraday cage to be a completely shielded enclosure which could be a >> metal automobiole body, a steel rebar reinforced concrete structure >> or a screened room. These all tend to completely block both the >> E-field and the H-field components of an electromagnetic wave. > > > Sorry, I meant "Faraday screen", which is the term you used, and I used > in my posting explaining its operation. > > If you block either the E or H field, you also block the other. You > can't independently block one or the other. > >> . . . > > >> Why would one pay a lot of extra money for a transformer which >> eliminated capacitive coupling if it didn`t work, especially in >> Havana, Cuba? > > > Because in order to "work" it doesn't need to "eliminate capacitive > coupling". All it needs to do is locally reduce the E/H field ratio, > which is what it does. > > Roy Lewallen, W7EL It might be useful to also point out the means by which these electric and/or magnetic shields do their job. They do it not so much by blocking as much as by diverting the fields. They serve to conduct the field around the object that is being shielded. 73 de ac6xg Article: 219835 of rec.radio.amateur.antenna From: Phil Wheeler Subject: Re: C. Crane's Twin Ferrite Antenna References: Message-ID: <0uklf.4451$hI1.3077@tornado.socal.rr.com> Date: Tue, 06 Dec 2005 18:10:04 GMT W. Watson wrote: > This is really weird. The noise stopped! Not to worry. It will likely return :-; Article: 219836 of rec.radio.amateur.antenna From: Michael Coslo Subject: Re: C. Crane's Twin Ferrite Antenna Date: Tue, 06 Dec 2005 13:28:30 -0500 Message-ID: References: W. Watson wrote: > This is really weird. The noise stopped! There's no question that when I > first noticed this some weeks ago that it was linked to turning the PC > on, and would disappear when I turned it off. I haven't changed anything. Just as a remote possibility, have you changed resolutions, or refresh rate on your monitor? - 73 de Mike KB3EIA - Article: 219837 of rec.radio.amateur.antenna From: Michael Coslo Subject: Re: dipole and balun question Date: Tue, 06 Dec 2005 13:32:45 -0500 Message-ID: References: <%e0lf.43999$i7.18434@bignews2.bellsouth.net> <__0lf.44003$i7.4483@bignews2.bellsouth.net> Bob Miller wrote: > On Mon, 5 Dec 2005 14:02:03 -0600, "RB" > wrote: > > >>Oooopss----I meant coax fed. >> > > > If you're really going to feed the antenna with coax, why do you need > a balun? Just run the coax straight to your tuner coax connection. Sometimes an antenna needs matched to the coax line. An extreme example is an OCF dipole, which can operate on several bands, but has an impedence of several hundred ohms. the 4:1 or 6:1 balun will match that with the 50 ohm coax. - 73 de Mike KB3EIA - Article: 219838 of rec.radio.amateur.antenna From: Gene Fuller Subject: Re: Antenna reception theory References: <11p322i7mfa917d@corp.supernews.com> <11p4qke5i7jv82b@corp.supernews.com> <11p54qa720fpf1b@corp.supernews.com> <11p5blcru430q9d@corp.supernews.com> <7YPkf.26664$dO2.972@newssvr29.news.prodigy.net> <020lf.125287$qk4.90216@bgtnsc05-news.ops.worldnet.att.net> <0t3lf.230043$zb5.115797@bgtnsc04-news.ops.worldnet.att.net> <1yglf.32224$Zv5.9900@newssvr25.news.prodigy.net> Message-ID: Date: Tue, 06 Dec 2005 18:54:32 GMT Cecil, I do not have a copy of Hecht, but I doubt that he has made any serious mistakes. Certainly he should have no mistakes in an area that is as well understand and widely discussed as plane wave interactions with discontinuities in the medium. The classic treatment of this problem, found in virtually every college-level textbook on E&M or optics, is to set up the appropriate wave equations, add the boundary conditions, and crank out the answer. Then there is typically some sort of analysis and discussion that says, "The reflected intensity plus the transmitted intensity is equal to the incident intensity. Energy is conserved." I suspect Hecht provides exactly that sort of description. I know that all of the relevant textbooks I have do so. I believe you are reading too much into something Hecht is saying, perhaps in an effort to somehow reconcile conservation of energy. The beauty of the laws of E&M, as expressed by Maxwell's equations and other fundamental properties, is that conservation of energy is automatic, at least in ordinary circumstances. If one correctly solves for the field equations, the energy conservation will come along for free. Conversely, it is customary to use energy considerations as the primary vehicle for addressing many physical problems in advanced mechanics, quantum mechanics, solid state physics, and other branches of science. The bottom line is that there are a number of tools available to develop correct solutions to physical problems. Steve Best chose one path, and you choose another. You both come up with the same answer in terms of what can be measured. The mathematical constructs underlying the solution may be different, but those constructs are not directly measurable. Don't limit your toolbox. Sometimes a screwdriver is easier to use than a monkey wrench. 73, Gene W4SZ Cecil Moore wrote: > Gene Fuller wrote: > >> I thought my intention was obvious, but it seems I failed to communicate. > > > Others on this newsgroup have admonished me for worrying about > energy and refused to discuss the subject. I thought you were > doing the same. Sorry. But do you actually have any references > that contradict "Optics", by Hecht? > > In Dr. Best's article, he superposes V1 with V2 such that constructive > interference energy is needed to complete the superposition. On this > newsgroup, I asked Dr. Best where that necessary constructive interference > energy comes from and he didn't know. That's when I went searching for > references and found them in the field of optics. > > Constructive interference energy can be supplied by local sources > as occurs in W7EL's "Food for Thought #1" with its DC example. Or > constructive interference energy can be supplied at a point away > from the source(s) by destructive interference, e.g. wave cancellation > at the non-reflection surface of a layer of thin-film on glass or > at a match point in a transmission line. Article: 219839 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Antenna reception theory References: <11p9h1kn73bctd4@corp.supernews.com> <13800-43950156-464@storefull-3254.bay.webtv.net> <11pa9quedgve336@corp.supernews.com> Message-ID: Date: Tue, 06 Dec 2005 18:57:21 GMT Reg Edwards wrote: > What have photons to do with winning a contest? ;o) Just try winning a contest without them. :-) -- 73, Cecil, http://www.qsl.net/w5dxp Article: 219840 of rec.radio.amateur.antenna From: Owen Duffy Subject: Re: dipole and balun question Message-ID: References: <%e0lf.43999$i7.18434@bignews2.bellsouth.net> Date: Tue, 06 Dec 2005 19:11:57 GMT On Tue, 6 Dec 2005 11:26:40 -0600, "Steve Nosko" wrote: >At the risk of starting something... Owen, I didn't see this point in your >initial post. I've read a few of your posts and you seem to give pretty >good explanations. The answer was in the graphs in the referenced article. If a reader would be satisfied by a simple answer, the answer is no, it isn't practical. But if they wanted to know why it wasn't practical, the information and a better solution were both in that article which was generally about the issue of whether the traditional wisdom of a dipole, one half wave long at the lowest operating frequency, fed with coax and "loaded up" with an ATU would be a good multiband antenna. >I thought the answer would be that a wideband Balun (my assumption that the >OP is referring to this type) of the type commonly used (Ferrite core & >windings) is not recommended for a multi-band antenna where the impedances >vary widely. These baluns, I thought, are suitable only for impedances near >their design center. For example, a 1:1 balun works well in a 50-50 ohm, >50-75 ohm or 75-75 or 50-33 ohm system. A 4:1 (or perhaps more correctly >1:4) works ok with 50-200. 50-300, 50-133. Steve, it is certainly a challenge to implement a balun that works over the range of impedances that would be encountered in a 140' dipole from 1.8 to 30 MHz. To my mind, the very high coax loss dismisses the solution before you visit the balun problem. Without detailed analysis, my guess is that the 140' dipole will be far enough off resonance to cause high coax loss on 80m, there is the slimmest chance that it would fall into 30m as a 3 x 1/2 waves, and it is unlikely to have low coax loss on any other band. Hence my statement that it is unlikely to have acceptable coax loss on any band, save possibly one. > >Using a 1:1 between tuner and antenna (at either end of the feed line) when >the antenna impedance may be 200 or 1000 ohms on some band, causes grief for >the balun in the form of poor efficiency and possibly a burned up balun - >because the balun is operating in a system impedance much different than >this design center. These baluns are not suitable for a wide range of >impedances. A design and implementation challenge, indeed. > > > >Do I need to change my brand of drink, or have I got a reasonable >understanding? > > > >Owen, > > It is my understanding that (ignoring patterns and focusing initially on >the antenna) using a dipole which is not resonant on one of the harmonically >related ham bands ( I believe the original Windom-circa 1945 and G5RV are in >this category) avoids the problem of matching to the very high impedance at >the even overtones (a 40M dipole is two half waves on 20M and a high Z). >Yes, using ladder line vs. coax helps with this greatly, but then you have >this age old problem of the bal to unbal issue. > >This, of course, somewhat ignores feed line loss, but this is a first >approximation focusing on the antenna initially - and I realize that >ignoring feed line loss is not what you do when looking at the WHOLE system. > >. I'll have to read your referenced article more fully (next). (:-) Ok, that is where the answer to the question about coax feed to a multi band dipole lays. The two graphs show (1, 1a) show in an instant that the problem is in the feedline, and other graphs show feedline solutions that are better. Nevertheless, the balun problem remains if you have an unbalanced ATU. I think the balun design can't be adequately addressed by considering just passive component between an unbalanced generator and balanced / floating load. A more complete answer is found by modelling the entire system (inc real balun and feedline) as part of the antenna system in NEC. The unbalanced shunt L and the value of the series R and L introduced by real baluns will have different effects depending on the length of the feeder, where it is earthed, how it is coupled to the nominal radiator etc. This approach is interesting in considering whether the balun should be on the tx or ant side of the ATU. I ran a range of models following my G5RV article at http://www.vk1od.net/G5RV/index.htm exploring baluns in that context, and finding a solution that reduces common mode feedline current significantly is challenging. The closest I came was a W2DU style choke balun that was four times (or more) the traditional lengths, and would reduce common mode feeline current to less than 10% of the nominal radiator current. It is a work in progress! I lament the unavailability of quality commercial ATUs that deliver uncompromised balanced output. (Yes, I know MFJ have recently released a product, but I did say "quality"). Owen -- Article: 219841 of rec.radio.amateur.antenna From: Owen Duffy Subject: Re: measuring antenna resonance with an 8405a Message-ID: References: <3M-dnWU27IqxggjenZ2dnUVZ_sydnZ2d@comcast.com> Date: Tue, 06 Dec 2005 19:18:50 GMT On Tue, 06 Dec 2005 11:37:04 -0700, Wes Stewart wrote: >Maybe I misunderstand, but what you seem to be saying is that if I put >Probe A at point X on a transmission line and Probe B at point X+Y >(Y>0), the phase difference with respect to frequency will not change. > >The directional coupler is no different, it is sampling the main line >at two physically different locations. With respect, I think you two guys are talking about different kinds of couplers. Wes, your earlier description makes is clear that samples in the coupler you described are located at equidistant from their nearest ends, but not in the centre, so at different positions in the coupler. I think the coupled lines type of coupler for lower frequency use might fit this category. Frank assumes a coupler where the samples for both ports are taken at the same physical location on the main line. I think a crossed waveguide coupler might fit this category (depending on the way the coupling holes are implemented). Owen -- Article: 219842 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Antenna reception theory References: <11p4qke5i7jv82b@corp.supernews.com> <11p54qa720fpf1b@corp.supernews.com> <11p5blcru430q9d@corp.supernews.com> <7YPkf.26664$dO2.972@newssvr29.news.prodigy.net> <020lf.125287$qk4.90216@bgtnsc05-news.ops.worldnet.att.net> <0t3lf.230043$zb5.115797@bgtnsc04-news.ops.worldnet.att.net> <1yglf.32224$Zv5.9900@newssvr25.news.prodigy.net> Message-ID: <0yllf.29710$q%.16771@newssvr12.news.prodigy.com> Date: Tue, 06 Dec 2005 19:22:36 GMT Gene Fuller wrote: > I do not have a copy of Hecht, but I doubt that he has made any serious > mistakes. It would be worth your while to visit a local university and check out Hecht's chapters on superposition and interference. > "The reflected intensity plus the transmitted intensity is equal to the > incident intensity. Energy is conserved." I suspect Hecht provides > exactly that sort of description. Much more than that. As you know, irradiance is power/unit-area and Hecht spends many pages on irradiance and energy. > I believe you are reading too much into something Hecht is saying, > perhaps in an effort to somehow reconcile conservation of energy. Spoken by someone who hasn't even read Hecht? I suspect if you read Hecht, you would perceive the same information as I. Hecht is big on conservation of energy and spends many pages discussing such things involving EM waves. > The beauty of the laws of E&M, as expressed by Maxwell's equations and > other fundamental properties, is that conservation of energy is > automatic, at least in ordinary circumstances. There is still an underlying Q&A about what happens to the energy in those waves. The energy concept is in addition to what's already there, not any kind of replacement for it. > The bottom line is that there are a number of tools available to develop > correct solutions to physical problems. Steve Best chose one path, and > you choose another. Nope, we chose the same path. Steve just fell off the path and down the cliff about 2/3 of the way through his articles. Steve gave us a very good picture of what happens to the energy toward the load but he gave us a distorted view of what happens to the energy toward the source. Instead of Steve's one-sided approach, I presented both sides thus merely expanding what Steve had already done. > Don't limit your toolbox. Funny, just above you seemed to recommend limiting the toolbox to Maxwell's equations and tried to discourage me from thinking about energy. -- 73, Cecil, http://www.qsl.net/w5dxp Article: 219843 of rec.radio.amateur.antenna From: Gene Fuller Subject: Re: Antenna reception theory References: <11p54qa720fpf1b@corp.supernews.com> <11p5blcru430q9d@corp.supernews.com> <7YPkf.26664$dO2.972@newssvr29.news.prodigy.net> <020lf.125287$qk4.90216@bgtnsc05-news.ops.worldnet.att.net> <0t3lf.230043$zb5.115797@bgtnsc04-news.ops.worldnet.att.net> <1yglf.32224$Zv5.9900@newssvr25.news.prodigy.net> <0yllf.29710$q%.16771@newssvr12.news.prodigy.com> Message-ID: Date: Tue, 06 Dec 2005 19:37:56 GMT Cecil, The waves you are so worried about are merely convenient, but fictitious, adjuncts to your mathematical model. You need worry only about the energy of real, measurable waves, not those adjuncts that simplify the math. The use of such adjuncts is done frequently in solving real problems. Just don't confuse the internals of the model with physical reality. 73, Gene, W4SZ Cecil Moore wrote: > There is still an underlying Q&A about what happens to the energy > in those waves. The energy concept is in addition to what's already > there, not any kind of replacement for it. Article: 219844 of rec.radio.amateur.antenna From: Jim Kelley Subject: Re: Antenna reception theory Date: Tue, 06 Dec 2005 11:47:24 -0800 Message-ID: References: <11p54qa720fpf1b@corp.supernews.com> <11p5blcru430q9d@corp.supernews.com> <7YPkf.26664$dO2.972@newssvr29.news.prodigy.net> <020lf.125287$qk4.90216@bgtnsc05-news.ops.worldnet.att.net> <0t3lf.230043$zb5.115797@bgtnsc04-news.ops.worldnet.att.net> <1yglf.32224$Zv5.9900@newssvr25.news.prodigy.net> <0yllf.29710$q%.16771@newssvr12.news.prodigy.com> Gene Fuller wrote: > Cecil, > > The waves you are so worried about are merely convenient, but > fictitious, adjuncts to your mathematical model. > > You need worry only about the energy of real, measurable waves, not > those adjuncts that simplify the math. > > The use of such adjuncts is done frequently in solving real problems. > Just don't confuse the internals of the model with physical reality. > > 73, > Gene, > W4SZ Might this be an example, Gene? From "An Energy Analysis at an Impedance Discontinuity in an RF Transmission Line, Part I" "100% wave cancellation means 100% energy reflection." 73 de ac6xg Article: 219845 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Antenna reception theory References: <11p54qa720fpf1b@corp.supernews.com> <11p5blcru430q9d@corp.supernews.com> <7YPkf.26664$dO2.972@newssvr29.news.prodigy.net> <020lf.125287$qk4.90216@bgtnsc05-news.ops.worldnet.att.net> <0t3lf.230043$zb5.115797@bgtnsc04-news.ops.worldnet.att.net> <1yglf.32224$Zv5.9900@newssvr25.news.prodigy.net> <0yllf.29710$q%.16771@newssvr12.news.prodigy.com> Message-ID: Date: Tue, 06 Dec 2005 20:31:12 GMT Gene Fuller wrote: > The waves you are so worried about are merely convenient, but > fictitious, adjuncts to your mathematical model. Let's see: 1. Canceled waves are "fictitious adjuncts to my math model". 2. Therefore, they don't need to be canceled, because they are only "fictitious adjuncts to my math model". 3. Therefore, we can remove whatever is doing the canceling of those "fictitious adjuncts" without changing anything. 4. Darn, how is it that I can see those "fictitious adjuncts to my math model" so well that I can't see anything else? What's wrong with this picture? Could there be a not-so-hidden contradiction accompanied by confusion of cause and effect? > You need worry only about the energy of real, measurable waves, not > those adjuncts that simplify the math. You don't even know me, Gene. Where do you get the balls to decide what I need to worry about and what I don't need to worry about? I have been worried and needing an energy analysis model for 40 years. I now have one and can now sleep like a baby at night, but no thanks to you. :-) -- 73, Cecil, http://www.qsl.net/w5dxp Article: 219846 of rec.radio.amateur.antenna From: "Asimov" Subject: Re: Antenna reception theory Message-ID: References: <11pbil7r81dkk7e@corp.supernews.com> Date: Tue, 06 Dec 2005 21:01:18 GMT "Joel Kolstad" bravely wrote to "All" (06 Dec 05 09:28:55) --- on the heady topic of "Re: Antenna reception theory" JK> From: "Joel Kolstad" JK> Xref: core-easynews rec.radio.amateur.antenna:220898 JK> "Richard Harrison" wrote in message JK> news:13799-4395B134-1973@storefull-3254.bay.webtv.net... > Richard Clarks advice is good. Arnold B. Bailey in "TV and Other > Receiving Antennas" [,,,] JK> It's out of print, but I've requested a copy through interlibrary JK> loan. I'm curious to see what he has to say on the standard V-shaped JK> rabbit ears that have been in use for decades... although one can JK> readily simulate them and see exactly how they perform, I've yet to JK> find anyone who had a good idea as to why rabbit ears haven't JK> traditionally been oriented purely horizontally! I think the reason why you don't see rabbit ears oriented horizontally is that they don't seem to work well as dipoles. When standing up they aren't even a V antenna and at first one would think they are vertically polarized but they are somewhat directive with a bipolar pattern. Rabbit ears are a bastardized form of a couple antenna types. Sometimes mainly one element is responsible for most of the signal while the other behaves as a reference or ground. For example on low frequency channels like Ch-3, reception is best if one of the elements is oriented straight up and the other horizontally pointing in the direction of the transmitter. This won't work well with Ch-12 and the standing V is best then. A*s*i*m*o*v ... Men are men and needs must err. - Euripides Article: 219847 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Antenna reception theory References: <11p5blcru430q9d@corp.supernews.com> <7YPkf.26664$dO2.972@newssvr29.news.prodigy.net> <020lf.125287$qk4.90216@bgtnsc05-news.ops.worldnet.att.net> <0t3lf.230043$zb5.115797@bgtnsc04-news.ops.worldnet.att.net> <1yglf.32224$Zv5.9900@newssvr25.news.prodigy.net> <0yllf.29710$q%.16771@newssvr12.news.prodigy.com> Message-ID: Date: Tue, 06 Dec 2005 21:07:27 GMT Jim Kelley wrote: > "100% wave cancellation means 100% energy reflection." That's a no-brainer when quoted in the context of an RF transmission line. Shame on you for once again quoting something out of context. If it happened in space, it would say, "100% wave cancellation means 100% energy redistribution." as explained on the web pages below. There are only two directions in a transmission line. If energy rejected by a mismatched load doesn't make it to the source, in a lossless system, it must necessarily be 100% re-reflected. Rho^2 is reflected by the impedance discontinuity at the match point. That's step one. Step two is that 100% wave cancellation. Given those two steps, no reflected energy flows toward the source. Therefore, it must necessarily have been re-reflected back toward the load. Since it joins the forward energy wave, we can measure that is exactly what happens. It's a no-brainer. Here's the in-context quote. The destructive interference energy resulting from wave cancellation at an impedance discontinuity becomes an equal magnitude of constructive interference in the opposite direction. Since there are only two directions in a transmission line, wave cancellation is the equivalent of an energy reflection. 100% wave cancellation means 100% energy reflection. [9] [9] Quotes from two web pages from the field of optical engineering: www.mellesgriot.com/products/optics/oc_2_1.htm "Clearly, if the wavelength of the incident light and the thickness of the film are such that a phase difference exists between reflections of p, then reflected wavefronts interfere destructively, and overall reflected intensity is a minimum. If the two reflections are of equal amplitude, then this amplitude (and hence intensity) minimum will be zero." "In the absence of absorption or scatter, the principle of conservation of energy indicates all ‘lost’ reflected intensity will appear as enhanced intensity in the transmitted beam. The sum of the reflected and transmitted beam intensities is always equal to the incident intensity. This important fact has been confirmed experimentally." http://micro.magnet.fsu.edu/primer/java/scienceopticsu/interference/waveinteractions/index.html "... when two waves of equal amplitude and wavelength that are 180-degrees ... out of phase with each other meet, they are not actually annihilated, ... All of the photon energy present in these waves must somehow be recovered or redistributed in a new direction, according to the law of energy conservation ... Instead, upon meeting, the photons are redistributed to regions that permit constructive interference, so the effect should be considered as a redistribution of light waves and photon energy rather than the spontaneous construction or destruction of light." Note from W5DXP: In an RF transmission line, since there are only two possible directions, the only "regions that permit constructive interference" at an impedance discontinuity is the opposite direction >from the direction of destructive interference. -- 73, Cecil, http://www.qsl.net/w5dxp Article: 219848 of rec.radio.amateur.antenna From: Gene Fuller Subject: Re: Antenna reception theory References: <11p5blcru430q9d@corp.supernews.com> <7YPkf.26664$dO2.972@newssvr29.news.prodigy.net> <020lf.125287$qk4.90216@bgtnsc05-news.ops.worldnet.att.net> <0t3lf.230043$zb5.115797@bgtnsc04-news.ops.worldnet.att.net> <1yglf.32224$Zv5.9900@newssvr25.news.prodigy.net> <0yllf.29710$q%.16771@newssvr12.news.prodigy.com> Message-ID: Date: Tue, 06 Dec 2005 22:15:34 GMT Cecil, Sorry, I mistakenly thought the discussion was about technology. Silly me! Since it is actually about psychology, not physics, I am outta here. 73, Gene W4SZ Cecil Moore wrote: > You don't even know me, Gene. Where do you get the balls to > decide what I need to worry about and what I don't need to > worry about? I have been worried and needing an energy analysis > model for 40 years. I now have one and can now sleep like a baby > at night, but no thanks to you. :-) Article: 219849 of rec.radio.amateur.antenna From: "Ed Laughery" Subject: Problem with dual band antenna Message-ID: Date: Tue, 6 Dec 2005 16:18:56 -0600 Hi I installed a NOS dual band (2m/70cm) thru glass antenna on my Toyota Highlander today. This a Radio Shack antenna that was carried in the stores about two years ago. I made sure to mount on glass away from defroster lines, no metal film sun screen, and away from major metal. Using my MFJ analyzer, the best SWR on two meters is 5.9 - 6.1, SWR on 70 cm is a 2.0 - 2.2. The interior interface block has a trimmer cap that is working - SWR is affected but will not improve beyond the cited numbers.. I tried sweeping thru a board range of frequencies in the 2 meter band and cannot find a resonant hotspot. The RS package indicates that the antenna should be 2.0 or less thru the bands with a VSWR around 1.1 at 146.00 and 445.00 MHz. Any ideas what may be the problem and/or what I might check. BTW: I checked other antennas with the same analyzer and they read correctly. Thanks in advance for your consideration. Ed Article: 219850 of rec.radio.amateur.antenna From: "Steve Nosko" Subject: Re: measuring antenna resonance with an 8405a Date: Tue, 6 Dec 2005 16:34:57 -0600 Message-ID: References: <3M-dnWU27IqxggjenZ2dnUVZ_sydnZ2d@comcast.com> "Wes Stewart" wrote in message news:juubp1h60np802f032kqqg7k72arb4fsr3@4ax.com... > On Tue, 06 Dec 2005 19:18:50 GMT, Owen Duffy wrote: > > >On Tue, 06 Dec 2005 11:37:04 -0700, Wes Stewart > >wrote: > > > > > >>Maybe I misunderstand, but what you seem to be saying is that if I put > >>Probe A at point X on a transmission line and Probe B at point X+Y > >>(Y>0), the phase difference with respect to frequency will not change. > >> > >>The directional coupler is no different, it is sampling the main line > >>at two physically different locations. > > > >With respect, I think you two guys are talking about different kinds > >of couplers. > > > >...Owen's coupler location discussion...> > May be, but his link: > > http://cp.literature.agilent.com/litweb/pdf/5952-8133.pdf > > shows exactly what I'm talking about in Figure 3. Note the line > stretcher on one sample port. Because I haven't seen the inside of one > of these I don't know where the coupled arms reside with respect to > each other but the fact that H-P shows the line stretcher tells me > that they must have some (unavoidable, if not purposeful) asymmetry. > They claim 4 degree phase tracking but it's unclear to me whether they > mean the coupled arms with respect to the main line or to each other. I have done this type of measurement and the coupler is somewhat un-important in regard to where on the line its samples are taken from. The line stretcher does the compensation to place both samples at the same point on the main line. It is set in a calibration process to get to that point (seems to mee only a short is required). Memory is starting to fade here, but if you want the samples to be "at the plane of the DUT" then you either must use two line stretchers or use the vector voltmeter capability to compensate for the difference in sample location vs. DUT location. If I recall correctly, this is simply a phase offset and the old HP vector voltmeter has such an offset capability. Look at it this way. You want the FWD and REF phases to be at the DUT. To do this you must put an equal (electrical) length of line in all three sections of line - the desired, the FWD sample and the reverse sample. I admit the reflected part has an intuitive glitch that I can't resolve at this time since it is always longer, but I know this works. You can sweep the set-up and the phase of the two samples will sit right there on that of a short . This rells you that the samples are "at the DUT". Right?? 73, Steve, K,9.D;C'I Article: 219851 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Antenna reception theory References: <7YPkf.26664$dO2.972@newssvr29.news.prodigy.net> <020lf.125287$qk4.90216@bgtnsc05-news.ops.worldnet.att.net> <0t3lf.230043$zb5.115797@bgtnsc04-news.ops.worldnet.att.net> <1yglf.32224$Zv5.9900@newssvr25.news.prodigy.net> <0yllf.29710$q%.16771@newssvr12.news.prodigy.com> Message-ID: Date: Tue, 06 Dec 2005 23:05:15 GMT Gene Fuller wrote: > Sorry, I mistakenly thought the discussion was about technology. > Silly me! We wouldn't have technology without the human need and drive to understand nature. Many great scientists were textbook examples of O-C personalities. -- 73, Cecil http://www.qsl.net/w5dxp Article: 219852 of rec.radio.amateur.antenna From: Owen Duffy Subject: Re: measuring antenna resonance with an 8405a Message-ID: References: <3M-dnWU27IqxggjenZ2dnUVZ_sydnZ2d@comcast.com> Date: Tue, 06 Dec 2005 23:13:35 GMT On Tue, 06 Dec 2005 14:22:31 -0700, Wes Stewart wrote: >May be, but his link: > >http://cp.literature.agilent.com/litweb/pdf/5952-8133.pdf > >shows exactly what I'm talking about in Figure 3. Note the line >stretcher on one sample port. Because I haven't seen the inside of one >of these I don't know where the coupled arms reside with respect to >each other but the fact that H-P shows the line stretcher tells me >that they must have some (unavoidable, if not purposeful) asymmetry. >They claim 4 degree phase tracking but it's unclear to me whether they >mean the coupled arms with respect to the main line or to each other. I could be wrong, but I think that 4 deg seems part of the tolerance of the phase alignment of the two sample ports wrt each other over the frequency range. Perhaps this is a coupler where the ports are approximately in phase, and perhaps the line strether is to adjust phase of forward and reflected ports to create a new reference plane where it is needed or convenient to the measurement. Owen -- Article: 219853 of rec.radio.amateur.antenna From: Cecil Moore Subject: One experience with noise Message-ID: Date: Tue, 06 Dec 2005 23:14:22 GMT A couple of days ago, my power failed right in the middle of a football game. I just happen to have a 12v deep discharge battery and a 12v B&W TV. I plugged it in, extended the two-foot telescoping antenna and, wonders of wonders, I was receiving a very good vhf TV signal from about 40 miles away. The game went on and after awhile the power came back on. That good TV picture simultaneously disappeared along with the sound. There may be a lesson there somewhere. -- 73, Cecil http://www.qsl.net/w5dxp Article: 219854 of rec.radio.amateur.antenna From: Owen Duffy Subject: Re: One experience with noise Message-ID: References: Date: Tue, 06 Dec 2005 23:28:15 GMT On Tue, 06 Dec 2005 23:14:22 GMT, Cecil Moore wrote: >A couple of days ago, my power failed right in the middle of a >football game. I just happen to have a 12v deep discharge battery >and a 12v B&W TV. I plugged it in, extended the two-foot telescoping >antenna and, wonders of wonders, I was receiving a very good vhf >TV signal from about 40 miles away. The game went on and after >awhile the power came back on. That good TV picture simultaneously >disappeared along with the sound. There may be a lesson there somewhere. I don't think you were telling us that the battery went flat at that moment, so... Don't you have digital television? Best thing since sliced bread. I don't know if you can receive analog television beyond the digital coverage ranges, but you probably wouldn't want to watch it. Digital TV makes weak signals most watchable, DVD quality at weak signals. I use it and I am only 4km from the transmitter, but that is another situation where it works a treat, ghost free pictures close to the tranmitter in the presence of local reflections (hills, water towers etc). Owen -- Article: 219855 of rec.radio.amateur.antenna From: "W. Watson" Subject: Re: C. Crane's Twin Ferrite Antenna References: Message-ID: <3dplf.246$Tg2.59@newsread1.news.pas.earthlink.net> Date: Tue, 06 Dec 2005 23:33:19 GMT Michael Coslo wrote: > > > W. Watson wrote: > >> This is really weird. The noise stopped! There's no question that when >> I first noticed this some weeks ago that it was linked to turning the >> PC on, and would disappear when I turned it off. I haven't changed >> anything. > > > > Just as a remote possibility, have you changed resolutions, or refresh > rate on your monitor? > > > - 73 de Mike KB3EIA - > Good question. I recall trying to change, unsuccessfully. Hmmmmm. -- Wayne T. Watson (Watson Adventures, Prop., Nevada City, CA) (121.015 Deg. W, 39.262 Deg. N) GMT-8 hr std. time) Obz Site: 39° 15' 7" N, 121° 2' 32" W, 2700 feet Traveling in arid or desert country? Check your boots well to see if you have a scorpion in them. -- Survivorman, Discovery (SCI) Channel Web Page: Article: 219856 of rec.radio.amateur.antenna From: "Steve Nosko" Subject: Re: measuring antenna resonance with an 8405a Date: Tue, 6 Dec 2005 18:07:34 -0600 Message-ID: References: <3M-dnWU27IqxggjenZ2dnUVZ_sydnZ2d@comcast.com> <6Pnlf.138047$y_1.50980@edtnps89> "Frank" wrote in message news:6Pnlf.138047$y_1.50980@edtnps89... > > > The type of coupler I am thinking of is indeed where the coupling lines for > forward and reflected are in the same physical region. The point I was > making refers particularly to the HP 778D; where it is specified in: > http://cp.literature.agilent.com/litweb/pdf/5952-8133.pdf > "Data can be read from the two meters of the vector voltmeter and > transferred directly to a Smith Chart". Indicating that there is no > significant phase error over the nominal bandwidth of the coupler. The old vector voltmeter has a phase offset ability to compensate. > Just read Wes' comments on the line stretcher on the above pdf. I must > admit I also wondered about that, but assume it is intended as a cal > adjustment for a short/open standard. See my previous post on this. It IS used to get both samples "At the measurement plane." 73, Steve, K,9.D;C'I Article: 219857 of rec.radio.amateur.antenna From: "Steve Nosko" Subject: Re: Antennas And Lightning Induced Voltage Transients Date: Tue, 6 Dec 2005 18:13:04 -0600 Message-ID: References: "Robert11" wrote in message news:po2dnQQrb_pbcgjenZ2dnUVZ_tydnZ2d@comcast.com... > Hello: > > We get a lot of lightning strikes around here, and was wondering about this: > > Presently have a receive-only random length wire running around the inside > of my attic.... > > But, does the roof provide any protection ... > > Or, is the fact that it is indoors really meaningless ? > Thanks, Bob The roof has absolutely no significant magnetic properties, right? SO... the high current of the lightning is the "primary" of a transformer. The wire in your attic is the "secondary" of a transformer. A pretty poor transformer, but with that current, it'll induce lots'a voltage in your wire...roof or no roof. Right? 73, Steve, K,9.D;C'I Article: 219858 of rec.radio.amateur.antenna From: "Reg Edwards" Subject: Re: Antennas And Lightning Induced Voltage Transients Date: Wed, 7 Dec 2005 02:04:11 +0000 (UTC) Message-ID: References: The roof protects the antenna from lightning, even the sneaky stuff. All you have to worry about is lightning striking the roof and yourself if you are not under it. ---- Reg.