Article: 221901 of rec.radio.amateur.antenna From: Roy Lewallen Subject: Re: Vertical vs Horizontal shootout part one Date: Mon, 06 Mar 2006 18:43:22 -0800 Message-ID: <120psqeeu4hiad9@corp.supernews.com> References: <120ngtl3drs574@corp.supernews.com> <0HZOf.57636$g47.18172@tornado.tampabay.rr.com> <120p1rocfoni584@corp.supernews.com> <440ca00e_5@newsfeed.slurp.net> <120pbesgie9bdd3@corp.supernews.com> Gary Schafer wrote: > . . . > The calibration points that Mike did on his receiver should be valid > for any band for his antenna comparisons. An actual signal strength > measurement is not required nor would it be valid between bands. All > that is really needed is the difference measurements between the two > antennas so his calibration between points on the meter scale will be > valid on any band. I'm not sure I fully understand this. The difference from one S meter division to another *is* likely to be different on different bands, since it depends on the gain-vs-voltage characteristics of the controlled stages which can vary with frequency. But I do agree that he can make good comparative antenna measurements without good S meter calibration, because he has a step attenuator. By simply setting the attenuator so he gets the same S-meter reading on both antennas, S-meter calibration is completely irrelevant -- the antenna gain difference is the attenuator setting. I find it useful, however, to be able to see the difference with reasonable accuracy just by looking at my S meter. But that does require calibration for the band in use. >. . . Roy Lewallen, W7EL Article: 221903 of rec.radio.amateur.antenna From: Bob Miller Subject: Re: does doppler systems work only for unmodulated continous wave signals? Message-ID: References: <1141647965.814664.310580@i39g2000cwa.googlegroups.com> Date: Tue, 07 Mar 2006 03:15:26 GMT On 6 Mar 2006 04:26:05 -0800, "mazerom" wrote: >the doppler shift is fundamentally a tone frequency brought about by a >continuous wave source moving in and out. is it possible to have >reliable doppler shift when our source is spread spectrum or say some >form of digital modulation? Back around '57 or so, the beep-beeping of the Sputnik satellite was used to track its orbit by measuring the Doppler effect. bob k5qwg Article: 221904 of rec.radio.amateur.antenna From: stananger < stananger@********.***> Subject: Sun's next 11-year cycle could be 50 pct stronger Message-ID: Date: Tue, 07 Mar 2006 04:50:32 GMT Sun's next 11-year cycle could be 50 pct stronger Mon Mar 6, 2006 3:49 PM ET By Deborah Zabarenko WASHINGTON (Reuters) - Sun-spawned cosmic storms that can play havoc with earthly power grids and orbiting satellites could be 50 percent stronger in the next 11-year solar cycle than in the last one, scientists said on Monday. Using a new model that takes into account what happens under the sun's surface and data about previous solar cycles, astronomers offered a long-range forecast for solar activity that could start as soon as this year or as late as 2008. They offered no specific predictions of solar storms, but they hope to formulate early warnings that will give power companies, satellite operators and others on and around Earth a few days to prepare. "This prediction of an active solar cycle suggests we're potentially looking at more communications disruptions, more satellite failures, possible disruptions of electrical grids and blackouts, more dangerous conditions for astronauts," said Richard Behnke of the Upper Atmosphere Research Section at the National Science Foundation. "Predicting and understanding space weather will soon be even more vital than ever before," Behnke said at a telephone news briefing. The prediction, roughly analogous to the early prediction of a severe hurricane season on Earth, involves the number of sunspots on the solar surface, phenomena that have been monitored for more than a century. TWISTED MAGNETIC FIELDS Every 11 years or so, the sun goes through an active period, with lots of sunspots. This is important, since solar storms -- linked to twisted magnetic fields that can hurl out energetic particles -- tend to occur near sunspots. The sun is in a relatively quiet period now, but is expected to get more active soon, scientists said. However, there is disagreement as to whether the active period will start within months -- late 2006 or early 2007 -- or years, with the first signs in late 2007 or early 2008. Whenever it begins, the new forecasting method shows sunspot activity is likely to be 30 percent to 50 percent stronger than the last active period. The peak of the last cycle was in 2001, the researchers said, but the period of activity can span much of a decade. The strongest solar cycle in recent memory occurred in the late 1950s, when there were few satellites aloft, no astronauts in orbit and less reliance on electrical power grids than there is now. If a similarly active period occurred now, the impact would be hard to predict, according to Joseph Kunches of the National Oceanic & Atmospheric Administration's Space Environment Center in Colorado. "It's pretty uncertain what would happen, which makes this work more relevant," Kunches said. "What we have here is a prediction that the cycle is going to be very active, and what we need and what we're of course working on is to be able to predict individual storms with a couple days or hours in advance so the grids can take the action," Behnke said. Article: 221905 of rec.radio.amateur.antenna From: mcalhoun@ksu.edu Subject: Re: Current through coils Date: 6 Mar 2006 23:19:04 -0600 Message-ID: References: <12478-440C75C1-945@storefull-3258.bay.webtv.net> >....[snip].... >The measured current at the bottom of a loading coil is primarily >standing wave current. IT IS NOT FLOWING. >....[snip].... My obviously-overloaded must-be-pea-sized brain sure has trouble thinking of current which is NOT flowing, since my basic internal definition of "current" is something like "electrons flowing past a point". I'm enjoying reading this thread, but, what with all the difficulties my brain is having with such subtle points, I'm NOT learning much! -- --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: 221906 of rec.radio.amateur.antenna From: "Reg Edwards" Subject: Re: Current through coils Date: Tue, 7 Mar 2006 05:51:14 +0000 (UTC) Message-ID: References: <21271-440BE4B3-805@storefull-3254.bay.webtv.net> A coil inevitably occupies space. In particular, one of its dimensions is length. Therefore it can be, and indeed for accurate modelling always should be, treated as a component having distributed L, C and R. It just makes the mathematics somewhat more complicated. Hyperbolic functions can be involved. Like a transmission line, a coil possesses Zo, phase-shift, attenuation and Q. It is why my coil-loaded antenna programs provide answers in the right ball-park although I havn't a clue about the rules which govern the American ball game. By the way, reflections and standing waves are irrelevant and don't enter the argument. Sorry Cecil! ---- Reg, G4FGQ. Article: 221907 of rec.radio.amateur.antenna From: "Reg Edwards" Subject: Re: Vertical vs Horizontal shootout part one Date: Tue, 7 Mar 2006 05:59:50 +0000 (UTC) Message-ID: References: <120ngtl3drs574@corp.supernews.com> <0HZOf.57636$g47.18172@tornado.tampabay.rr.com> <120p1rocfoni584@corp.supernews.com> Roy, you appear to have mislaid your sense of humor. Hope you recover it soon. ;o) ---- Reg. Article: 221908 of rec.radio.amateur.antenna From: "Reg Edwards" Subject: Re: Current through coils Date: Tue, 7 Mar 2006 06:35:30 +0000 (UTC) Message-ID: References: <12478-440C75C1-945@storefull-3258.bay.webtv.net> Myron, I'm afraid Cecil has a fixation about standing waves and reflections. He brings them into arguments on every possible occasion. Nevertheless he is very convincing and manages to drag most people in. Give your brain a rest. Visit your nearest barber shop and tune up. You will feel much better. ---- Reg. Article: 221909 of rec.radio.amateur.antenna From: "Reg Edwards" Subject: Re: Sun's next 11-year cycle could be 50 pct stronger Date: Tue, 7 Mar 2006 06:49:05 +0000 (UTC) Message-ID: References: Are you sure 'Earth Warming', we hear so much about, has nothing to do with it? Article: 221910 of rec.radio.amateur.antenna From: stananger < stananger@********.***> Subject: Re: Sun's next 11-year cycle could be 50 pct stronger References: Message-ID: <_EaPf.5022$CT.3527@trnddc04> Date: Tue, 07 Mar 2006 07:31:06 GMT Reg Edwards wrote: > Are you sure 'Earth Warming', we hear so much about, has nothing to do > with it? maybe its the sunspots that are causing the so called warming! Article: 221911 of rec.radio.amateur.antenna From: "Reg Edwards" Subject: Re: Sun's next 11-year cycle could be 50 pct stronger Date: Tue, 7 Mar 2006 08:03:45 +0000 (UTC) Message-ID: References: <_EaPf.5022$CT.3527@trnddc04> > > Are you sure 'Earth Warming', we hear so much about, has nothing to do > > with it? > > > maybe its the sunspots that are causing the so called warming! ========================================== If its nothing to do with the price of oil perhaps we can recall our troops from the Middle East and release Saddam. Article: 221912 of rec.radio.amateur.antenna From: richardharrison@webtv.net (Richard Harrison) Subject: Re: Current through coils Date: Tue, 7 Mar 2006 01:59:01 -0600 Message-ID: <16154-440D3D45-967@storefull-3256.bay.webtv.net> References: Myron A. Calhoun wrote: "--I`m not learning much." Alas, I`d wager I don`t have anything new for Professor Calhoun, but >from some of the postings, what I write may be new in part to someone. Current is defined as movement of electrons through a conductor. Obviously, an incomplete definition. As we know, there is beam current in the vacuum of a CRT, and that at r-f, skin-effect forces most electrons to the surface so that most electron movement is on or very near the surface of the conductor rather than "through" it. When currents of equal amplitude and opposite direction meet at various points along a perfect transmission line, as they might after a perfect reflection of the incident wave, one might measure zero amps at cancellation points along the line. These would be distributed periodically as the waves, in fixed phase relation and equal and opposite currents, coincide. The measurement of zero amps occurs because the ammeter is measuring both currents simultaneously. If a directional coupler is used to measure the current in each direction separately, it will be found that the currents traveling in opposite directions are passing through each other without effect. Standing waves are more manifestation than anything else. There was a PBS TV Channel appeal tonight. It Quoted Einstein as saying: "Nothing happens until something moves". Incident and reflected waves move on a transmission line but standing waves are stationary and don`t move. So, it is the incident and reflected waves that make something happen. Not the stationary waves. Circulating energy within a transmission line causes standing waves. Without a reflection, they don`t exist. Energy must be accepted by an antenna to be radiated. It is best if it is accepted on the first pass so that there are no more losses on additional passes. A perfect match at the antenna accepts energy on the first pass. A mismatched antenna produces an SWR. Magnitude of the SWR is an indication of how much mismatch there is. Best regards, Richard Harrison, KB5WZI Article: 221913 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Current through coils References: <12478-440C75C1-945@storefull-3258.bay.webtv.net> Message-ID: Date: Tue, 07 Mar 2006 09:37:56 GMT mcalhoun@ksu.edu wrote: > My obviously-overloaded must-be-pea-sized brain sure has trouble thinking > of current which is NOT flowing, since my basic internal definition of > "current" is something like "electrons flowing past a point". Forward current is a traveling wave and is flowing. Reflected current is a traveling wave and is flowing. Both can be represented by phasors. But since they are traveling in opposite directions, their phasors are rotating in opposite directions and their superposed sum always add up to the same constant phase angle = zero (in a thin wire). Given a 1/2WL (-90 deg to +90 deg) thin wire dipole fed in the center (at 0 deg) with 1.0 amps, the standing wave current magnitude on the antenna is cos(theta) and the phase angle is a constant zero degrees from end to end. Reference: Figure 14-2, page 464 of "Antennas for All Applications", by Kraus and Marhefka, 3rd edition. If the phasor sum of two currents is not rotating, it is not flowing. Since phasors, by definition, change phase at a rate of (2*pi*f) and the standing wave current doesn't change phase at all, I don't think standing wave current is a phasor. Standing wave current is what we measure on a standing-wave antenna like a 75m mobile center-loaded bugcatcher. -- 73, Cecil http://www.qsl.net/w5dxp Article: 221914 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Current through coils References: <16154-440D3D45-967@storefull-3256.bay.webtv.net> Message-ID: <7QcPf.38135$Jd.3617@newssvr25.news.prodigy.net> Date: Tue, 07 Mar 2006 09:59:31 GMT Richard Harrison wrote: > If a directional > coupler is used to measure the current in each direction separately, it > will be found that the currents traveling in opposite directions are > passing through each other without effect. Standing waves are more > manifestation than anything else. And this is equally true of standing wave antennas. Kraus goes as far as assuming the forward and reflected currents on a 1/2 wavelength thin-wire dipole are equal in magnitude so they must be close to equal in magnitude. I have estimated that the magnitude of the reflected current after the round trip to the end of the dipole and back to be in the ballpark of 90% of the forward current at the feedpoint. This entire episode of constant current through a loading coil is the result of thinking standing wave current flows. As you say it is a manifestation of our thinking process and our measurements. It doesn't flow at all. Incidentally, a horizontal dipole above earth can be analyzed as a single-wire transmission line system with the earth being the ground return path. Balanis says, "Standing wave antennas, such as the dipole, can be analyzed as traveling wave antennas with waves propagating in opposite directions (forwards and backwards) and represented by traveling wave currents If and Ib in Figure 10.1(a)." The forward current (If) through a loading coil is very close to constant magnitude. The reflected current (Ib) back through a loading coil is very close to constant magnitude. Their phasor sum is the standing wave current that we measure. There is no physics requirement that the phasor sum of the forward and reflected currents be of equal magnitude on both ends of the loading coil. -- 73, Cecil http://www.qsl.net/w5dxp Article: 221915 of rec.radio.amateur.antenna From: Owen Duffy Subject: Re: Reflection Loss Message-ID: References: <27174-440CEDDE-994@storefull-3257.bay.webtv.net> Date: Tue, 07 Mar 2006 10:09:35 GMT On Mon, 6 Mar 2006 20:20:14 -0600, richardharrison@webtv.net (Richard Harrison) wrote: >Owen Duffy wrote: >"In formula 4-22b of my copy of Terman, the term on the lhs is |rho| >which is the magnitude of the reflection coefficient." > >In my copy, 4-22b gives the "absolute value" of the reflection >coefficient (it is embraced with bars) which I believe means the >"absolute value" of a number or a symbol without reference to its >algebraic sign. > >(4-22b): >+or- reflection coefficient= >SWR-1 / SWR+1 > Richard, you seem to be dealing with reflection coefficient as a real number when in fact it is a complex number. Your definition of |rho| is inadequate when rho is complex. Terman actually says in the preceding text "The standing wave ratio S is one means of expressing the magnitude of the reflection coefficient; the exact relationship between the two is..." Your statement "On page 99 of Terman`s 1955 edition of "Electronic and Radio Engineering" (my textbook was an earlier edition) is found the formula to convert the reflection coefficient into SWR or vice versa. These two parameters are innexorably locked together by formulas (4-22a) and (4-22b)." is wrong where it says "convert the reflection coefficient into SWR or vice versa" in respect of the "vice-versa" because you ignore the fact that the reflection coefficient is a complex quantity, and that the "magnitude of reflection coefficient" is not the same thing as "reflection coefficient. You cannot calculate the reflection coefficient from the SWR (except of course the special case where SWR=1). You have cited Terman in support of your own loose words, but Terman's words are more carefully chosen and correct, yours are not, and the Terman reference does not support your misconception at all. Owen -- Article: 221916 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Current through coils References: <21271-440BE4B3-805@storefull-3254.bay.webtv.net> Message-ID: Date: Tue, 07 Mar 2006 10:13:30 GMT Reg Edwards wrote: > By the way, reflections and standing waves are irrelevant and don't > enter the argument. Sorry Cecil! I'm curious, Reg. With traveling wave energy flowing in both directions through a loading coil, how do you analyze it without taking the forward and reflected energy into account? All my reference equations have a term with a positive exponent for forward current and another term with a negative exponent for reflected current. -- 73, Cecil http://www.qsl.net/w5dxp Article: 221917 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: ferrite balun grades References: <5amq02tq3q0lh1ag7d724jbk55j3fj3t5b@4ax.com> Message-ID: Date: Tue, 07 Mar 2006 10:19:23 GMT Mike Newman wrote: > Any advice on which grade of ferrite would be most useful for a > feeedline balun choke effective at 70 cm? #68 material might work although I have never tried it. -- 73, Cecil http://www.qsl.net/w5dxp Article: 221918 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Current through coils References: <12478-440C75C1-945@storefull-3258.bay.webtv.net> Message-ID: Date: Tue, 07 Mar 2006 13:26:45 GMT Reg Edwards wrote: > I'm afraid Cecil has a fixation about standing waves and reflections. They are part and parcel of a distributed network analysis and are embedded in many transmission line equations. As far as the constant current through the coil goes: Neglecting losses, the forward current through a coil is constant magnitude with changing phase. The reflected current through a coil is constant magnitude with changing phase. Those conditions satisfy the necessary and sufficient conditions of the laws of physics concerning a coil. The laws of physics do not require the phasor sum of the forward current and reflected current to be constant magnitude. In fact, the laws of physics prohibit the standing wave current from being equal magnitude except at equidistant points from a current maximum or minimum. -- 73, Cecil http://www.qsl.net/w5dxp Article: 221919 of rec.radio.amateur.antenna From: "Jerry Martes" References: <5amq02tq3q0lh1ag7d724jbk55j3fj3t5b@4ax.com> Subject: Re: ferrite balun grades Message-ID: Date: Tue, 07 Mar 2006 15:18:33 GMT "Mike Newman" wrote in message news:5amq02tq3q0lh1ag7d724jbk55j3fj3t5b@4ax.com... > Any advice on which grade of ferrite would be most useful for a > feeedline balun choke effective at 70 cm? > Thanks de miken zl1bnb Hi Miken I've been using the tubular, high permeability ferrites designed for RFI suppression slipped over the RG-223 coax for a balun for vhf antennas. I am aware of the high loss with those ferrite tubes. I have been hoping the high permeability would present a high reactance to currents along the outside of the coax. So far, the tubes are working OK for my needs. Your mileage may vary. Jerry Article: 221920 of rec.radio.amateur.antenna From: "Fred W4JLE" References: <1141744648.582563.281170@j52g2000cwj.googlegroups.com> Subject: Re: Square cross-section elements? Date: Tue, 7 Mar 2006 10:37:25 -0500 Message-ID: <144cc$440da8b8$471c6203$27512@ALLTEL.NET> As they say, measure with a micrometer, mark with a crayon, and cut with an Ax. From my limited (50 years) experience, your picking fly crap out of pepper! The absolute perfectly modeled antenna will still have to be adjusted in it's environment. The difference between square and round tubing is insignificant unless your into the mental masturbation of caring everything out to 12 decimal places. I am sure that someone will venture forth with an example to show how important this is at some frequency, altitude, temperature, phase of the moon and barometric pressure. Such is the habit of the newsgroups denizens. The reality is YOU have square tubing, use it and enjoy the contacts. wrote in message news:1141744648.582563.281170@j52g2000cwj.googlegroups.com... > Anyone know how to use square rod in modelling programs? > > I'm sure it's a small effect, but I'm interested in the *proper* way to > account for it vs. round rod. > > I've used the mean radius of the inscribed and circumscribed circles > and that turned out fine, > but I don't have much ability to make good gain and F/R measurements. > > It seems that the corners could affect element coupling... > > Should I use the circle that has the same area? Maybe the geometric > mean of the radii of the inscribed and circumscribed circles? > > I've got a bunch of 1/4" square rod that I want to make 435MHz yagis > out of, and pretty much all web searches I could think of on square > antenna elements either get zero hits for being too specific or talk > about quads a lot. > > The square rod is great mechanically; I can slap a piece of PVC pipe on > a milling machine, mill 1/4" slots through very accurately spaced, and > hold the elements in with cable ties. > > Anyway, I'm just going to try the geometric mean and build another > antenna, but I'm interested in any comments on this. > > 73, > Dan > N3OX > www.n3ox.net > Article: 221921 of rec.radio.amateur.antenna From: "Caveat Lector" References: <_EaPf.5022$CT.3527@trnddc04> Subject: Sunspots and "The Little Ice Age" Message-ID: Date: Tue, 7 Mar 2006 08:45:57 -0800 Speaking of sunspots, saw a real eye opener on a TV show the other night about "The Little Ice Age" brrrrrr Some believe a contributing cause was low sunspot activity; See URL: http://en.wikipedia.org/wiki/Little_Ice_Age The impact on humanity was incredible- See URL: http://www2.sunysuffolk.edu/mandias/lia/little_ice_age.html -- CL -- I doubt, therefore I might be ! Article: 221922 of rec.radio.amateur.antenna From: richardharrison@webtv.net (Richard Harrison) Subject: Re: Reflection Loss Date: Tue, 7 Mar 2006 10:55:21 -0600 Message-ID: <4238-440DBAF9-964@storefull-3253.bay.webtv.net> References: Owen Duffy wrote: "Richard, You seem to be dealing with reflection coefficient as a real number when in fact it is a complex number." I plead guilty. Best regards, Richard Harrison, KB5WZI Article: 221923 of rec.radio.amateur.antenna From: Bob Bob Subject: Re: does doppler systems work only for unmodulated continous wave References: <1141647965.814664.310580@i39g2000cwa.googlegroups.com> <2mvtd3-4kv.ln1@p400bob.personal.cox.net> <1141669090.526184.282340@v46g2000cwv.googlegroups.com> Message-ID: Date: Tue, 07 Mar 2006 10:07:46 -0600 You know I am not quite sure how to answer that.. Doppler shift is a relative thing. If you are travelling at 100kph the signal/carrier whatever relative to you is unaffected. Relative to a RX that is relatively moving either towards or away from you a shift will be apparent. The entire transmitted spectrum will be affected, not just the "carrier". There will of course be a calculable difference in shift over the bandwidth of the signal as the lower end will shift less than the upper one more. Whether it will be a significant amount or not depends on your application. A +- 10MHz wide signal at 2.4GHz for example (100kph) would be close to an extra 1Hz of shift at the signal edges. As your relaitive velocities approach the speed of light other problems crop up. I dont quite remember Einstein's stuff on this. Since though I doubt I'll never get to experiment with it I dont need to go through it again! Is that what you were looking for? Cheers Bob VK2YQA K7ITM wrote: > > Bob wrote, "You'll get about +-200Hz shift with a speed of 100kph." > > Ahem. Care to qualify that as to the carrier or transmitted > frequency?? > Article: 221924 of rec.radio.amateur.antenna From: "Alfred Lorona" Subject: Bend in xmission line Date: Tue, 7 Mar 2006 09:15:06 -0800 Message-ID: <120rfv6k22v7s45@corp.supernews.com> Conventional wisdom cautions against sharp bends in open wire transmission line. What is the practical/quantifiable effect of violating this rule? How does the effect vary with the severity of the bend and does it vary with the distance along the line at which the bend occurs? Tnx es 73, AL. Article: 221925 of rec.radio.amateur.antenna From: Allodoxaphobia Subject: Re: Sun's next 11-year cycle could be 50 pct stronger Date: 7 Mar 2006 17:29:14 GMT Message-ID: References: On Tue, 07 Mar 2006 04:50:32 GMT, stananger wrote: > Sun's next 11-year cycle could be 50 pct stronger <-snip-> > The prediction, roughly analogous to the early prediction of a severe > hurricane season on Earth, .... Translation: Academic Guessing Jonesy Article: 221926 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Current through coils References: <120nv3gt1f8gi3a@corp.supernews.com> <16154-440C20D8-847@storefull-3256.bay.webtv.net> <1141748066.033150.267940@v46g2000cwv.googlegroups.com> Message-ID: Date: Tue, 07 Mar 2006 18:01:18 GMT w8ji@akorn.net wrote: > I NEVER measured a current shift of 60 degrees, and I never said I > measured a current difference of 60 degrees. > > The phase shift I measured was in VOLTAGE. It simply shows the voltage > is out of step with the current. It doesn't indicate current is shifted > 60 degrees between each inductor terminal at all, and I never said it > did. The subject was Kraus' 180 degree current phase shifting coils. Here are you exact words (and all of your words about that measurement) quoted from qrz.com: > By the way, I swept S12 phase with my network analyzer on a 100uH > inductor a few hours ago while working on a phasing system. The > phase shift through that series inductor was about -60 or -70 degrees > on 1 MHz, crossing ZERO phase at self resonance (where loss became very > high) near 18 MHz, and gradually increasing leading phase above 18MHz > reaching 90 degrees and staying there well above resonance. I apologize for missing the small detail that S12 was a voltage measurement rather than a current measurement but I'm sure you can see how that was an honest mistake and easy to make. You didn't mention "voltage" at all in your posting and the context was current. I didn't recall until your objection here today that S12 is a voltage parameter measurement. But that leads to a question. Why were you using voltage measurements to try to disprove Kraus' statement about 180 degree current phase shifting coils. Quoting from: "Antennas for All Applications", Kraus and Marhefka, 3rd edition, page 824: "A coil (or trap) can also act as a 180 deg (current) phase shifter as in the collinear array ... The coil may also be thought of as a coiled-up 1/2WL element." > The current level at each end of the inductor was, as far as I can > measure with test equipment, equal. That sure doesn't make technical sense. If there was no phase shift in the current, then the voltage was lagging the current. But we know the current lags the voltage through an inductor by as much as 90 degrees in the ideal case. If the voltage is delayed by 60 degrees, then the current must necessarily be delayed by 60 degrees plus the lag to satisfy the laws of physics. If you will run the experiment using current probes, I assure you that the current will experience more of a phase shift than the voltage, just as the laws of physics predict. Which means there was more than a 60 deg current phase shift through the coil which makes my argument even stronger. Now, if you are talking only about the magnitude of the current then of course, the current was equal at both ends of the coil because reflected energy was absent for that measurement. IT IS THE PRESENCE OF REFLECTED ENERGY THAT MAKES FALSE YOUR ASSERTION ABOUT NET CURRENT. I think we are in perfect agreement about systems without reflections. > This is another clear case of Cecil taking things out of context ... Not out of context, Tom. The entire quote is just above. The mistake was an honest one and easy to make. I'm only human. :-) > and > mixing them with his idea that an inductor treats current differently, > depending on what direction it "flows" ... Sorry, I never said that. An inductor treats forward waves and reflected waves exactly the same according to the laws of physics. Your statement is more akin to your idea that standing wave current flows into the bottom of a coil and out the top. The coil treats all traveling waves exactly according to the laws of physics and exactly as you and I understand those laws of physics. I accept everything you say about traveling wave current through a coil. My argument with you is that a standing wave current is not a traveling wave current and doesn't behave like a traveling wave current. That seems rather obvious to me. 1. Just as you say, the forward traveling-wave current through a coil is of constant magnitude. Here's what Walter Maxwell says: "If an inductance is in series with a line that has no reflections, the current will be the same at both ends of the inductor." All three of us agree on that statment. 2. As in (1) above and just as you say, the reflected current through a coil is of constant magnitude. 3. There is no law of physics that requires the standing wave current to be equal at the top and bottom of a coil. In fact, such a requirement violates those laws of physics. Here's what Walter Maxwell says: "If an inductance is in series with a line that has reflections, the current will NOT be the same at both ends of the inductor. Consequently, circuit analysis will not work when both forward and reflected currents are present in a lumped circuit. When reflections are present, a current node and a current loop can appear at separate points on an inductor simultaneously." Judging from what he has posted earlier, Richard Harrison agrees with those statements. There's an EZNEC graphic at: http://www.qsl.net/w5dxp/qrzgif35.gif Would you have us believe that 0.1+ amps is flowing into the bottom of the coil and 0.7+ amps is flowing out of the top of the coil? It is your concept that standing wave current flows that is the problem. Please explain how a current with a zero phase angle >from tip to tip on a 1/2WL thin wire dipole can possibly flow without a rotating phase angle. > It is always better to let people directly post what they say, and not > have it run through a "Cecil Moore" filter. I agree, Tom, but you were not posting here so I quoted what I honestly thought you said over on qrz.com. I quoted the same thing on qrz.com over a number of days. You could have pointed out my mistake a lot sooner and saved me from making it here. -- 73, Cecil http://www.qsl.net/w5dxp Article: 221927 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Reflection Loss References: <4238-440DBAF9-964@storefull-3253.bay.webtv.net> Message-ID: <6XjPf.43231$F_3.5267@newssvr29.news.prodigy.net> Date: Tue, 07 Mar 2006 18:04:50 GMT Richard Harrison wrote: > Owen Duffy wrote: > "Richard, You seem to be dealing with reflection coefficient as a real > number when in fact it is a complex number." > > I plead guilty. OTOH, some text I have in my library treats 'rho' as a magnitude and 'gamma' as the complex reflection coefficient. -- 73, Cecil http://www.qsl.net/w5dxp Article: 221928 of rec.radio.amateur.antenna From: Roy Lewallen Subject: Re: Square cross-section elements? Date: Tue, 07 Mar 2006 10:45:27 -0800 Message-ID: <120rl6b4m08af5a@corp.supernews.com> References: <1141744648.582563.281170@j52g2000cwj.googlegroups.com> To model a square conductor with a round wire, use a wire diameter which is 1.18 times the side of the square. Roy Lewallen, W7EL n3ox.dan@gmail.com wrote: > Anyone know how to use square rod in modelling programs? > > I'm sure it's a small effect, but I'm interested in the *proper* way to > account for it vs. round rod. > . . . Article: 221929 of rec.radio.amateur.antenna From: Owen Duffy Subject: Re: Reflection Loss Message-ID: <0lmr02921e6b36p0udd4l0j21mpl0qc3sh@4ax.com> References: <4238-440DBAF9-964@storefull-3253.bay.webtv.net> <6XjPf.43231$F_3.5267@newssvr29.news.prodigy.net> Date: Tue, 07 Mar 2006 19:15:44 GMT On Tue, 07 Mar 2006 18:04:50 GMT, Cecil Moore wrote: >Richard Harrison wrote: > >> Owen Duffy wrote: >> "Richard, You seem to be dealing with reflection coefficient as a real >> number when in fact it is a complex number." >> >> I plead guilty. > >OTOH, some text I have in my library treats 'rho' as a magnitude >and 'gamma' as the complex reflection coefficient. Irespective of the symbol that may be used, and there are unfortunately many schemes, the reflection coefficient is a complex quantity. Owen -- Article: 221930 of rec.radio.amateur.antenna From: Michael Coslo Subject: Re: Vertical vs Horizontal shootout part one Date: Tue, 07 Mar 2006 14:18:47 -0500 Message-ID: References: <081n025fa3l0tk3ftnb464ga44sia7h7gh@4ax.com> Owen Duffy wrote: > On Sun, 05 Mar 2006 19:29:12 -0500, Mike Coslo > wrote: > >> Based on another thread a few weeks back in which Horizontal dipoles >> were being compared to Vertical antennas, and from a little chiding from >> Roy, W7EL, I decided to do some testing on my own personal versions of >> the two. >> > > Mike, this sounds interesting. Sorry for the delay getting back on-line... >> My setup is: >> >> Icom IC-761 >> Antenna 1 - Homebrew OCF dipole at ~ 50 feet. >> Antenna 2 - Butternut HF6V -ground mounted and 18 radials on the ground. >> > > Question, does the magnitude of feedline radiation from the OCF > (presumably predominantly vertical) significantly affect qualification > of it as a horizontal antenna? There shouldn't be any feedline radiationn, this is oan antenna running coax to a 4:1 balun at the feedpoint. > Another, are the antennas coupled significantly, eg is one within the > near field zone of the other? It is pretty hard to avoid in a > residential block on the low bands, and it will confuse the results > somewhat. Almost certainly there is some interaction. It isn't a very big yard. >> Part one of this experiment is to calibrate the S-meter. I found that >> trying to calibrate the thing with on-air signals was a nuisance, and >> probably wouldn't be as accurate, so I used a signal generator. >> >> I started out with a +20 signal, then worked my way down. >> >> +20 start >> S9 -18 db >> S8 -23 db >> S7 -26 db >> S6 -29 db >> S5 -32 db >> S4 -35 db >> S3 -37 db >> S2 -39 db >> S1 -41 db > > Not only is the shape of the scale an issue, but the granularity or > resolution, especially with LCD meters, or any meter where there are > discrete steps in the meter current (such as where a D/A converter > drives the meter movement). > > If you want to move beyond S meters, you could try FSM > (www.vk1od.net/fsm) and organise some constant carriers at known > distances / radiation angles that you could make a series of > measurements of and produce summary statistics (median and inter > quartile range) for each antenna type. > >> All in all, I would have to say that the meter tracks very well from S8 >> to S4, and the only place that wasn't that great was from S9 to S8. But >> considering the transient nature of the signals we are receiving, I >> would have to day that the S-meter is of reasonably close accuracy. >> >> With my newly calibrated S-meter I am ready to start looking at what the >> two different antennas are doing for me. I have a coaxial switch to jump >> back and forth between the two. My initial impressions are that there >> are some surprises. The difference in noise levels varies by antenna by >> band. On some bands the vertical is noisier, and on others it is the OCF >> dipole. Especially intriguing is that on PSK mode, where I can see >> several signals at one time, switching between antennas will attenuate >> some signals, while other signals increase in strength. I think that my >> vertical works better than I gave it credit for, but If I definitely >> want *both* antennas. > > I described a technique for assessing the relative performance of > mobile stations by having them transmit known constant carrier, each > station space about 200Hz and turning circles in a carpark near each > other, and to observe them at typical propagation distances with an > audio spectrum analyser, watching the relative strength of the > carriers. > > Your PSK setup is affording you the same type of comparison, and > provides a ready (and recordable) assessment of the relative strength > of the stations under the two antenna scenarios. Be great if you could > orchestrate stations at known distances as part of an organised test. I'll probably be doing the next best thing, which is to do a lookup of the various callsigns as I see them. The more I see of waterfall displays, the more I like them. I would love to see one as standard on an HF rig. - 73 de Mike KB3EIA - Article: 221931 of rec.radio.amateur.antenna From: Michael Coslo Subject: Re: Vertical vs Horizontal shootout part one Date: Tue, 07 Mar 2006 14:27:23 -0500 Message-ID: References: <120ngtl3drs574@corp.supernews.com> <0HZOf.57636$g47.18172@tornado.tampabay.rr.com> Reg Edwards wrote: > Roy says, >>> People who blindly assume the marks on their S-meters are 6 dB > apart >>> should take a good look at your calibration results. > > ======================================= > > The calibration of S-meters, 3dB or 6dB per S-point, has nothing to do > with which antenna produces the stronger received signal. It is purely > a comparison. Just use the same meter throughout the tests. It does allow me to make a stab at comparing those two antennas. As I continue on this test, it would be nice to have something that has some sort of calibration. Otherwise we might as well just go to say "works great" or "doesn't work well for all measurements. - 73 de Mike KB3EIA - Article: 221932 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: OT for Cecil or any other ex RRAPers References: <1141756042.224852.90540@j52g2000cwj.googlegroups.com> Message-ID: Date: Tue, 07 Mar 2006 19:27:10 GMT an_old_friend wrote: > years ago I remmebr somebody I think it was you cecil (but I have slpet > since then) said something about being to build or modtify some type of > CW kit for some other mode like RTTY etc, looking for the reference > care to help out? It might have been me but I just don't remember, sorry. -- 73, Cecil http://www.qsl.net/w5dxp Article: 221933 of rec.radio.amateur.antenna From: Michael Coslo Subject: Re: Vertical vs Horizontal shootout part one Date: Tue, 07 Mar 2006 14:44:05 -0500 Message-ID: References: <120ngtl3drs574@corp.supernews.com> <0HZOf.57636$g47.18172@tornado.tampabay.rr.com> <120p1rocfoni584@corp.supernews.com> <440ca00e_5@newsfeed.slurp.net> <120pbesgie9bdd3@corp.supernews.com> <1141684037.607691.234800@p10g2000cwp.googlegroups.com> <120pemmnd5voi9f@corp.supernews.com> Roy Lewallen wrote: > K7ITM wrote: >> I fully agree with Roy's comment about the AGC-derived S-meter output. >> As he says, the AGC characteristics are temperature dependent, and they >> are also dependent on the particular set of active devices (and to some >> extent the passives too) in the signal path. >> >> If you have access to a spectrum analyzer, chances are decent that it >> will have a well-calibrated amplitude readout. The one I use is >> accurate in a relative sense to a fraction of a dB over more than an >> 80dB range, and would certainly be sensitive enough for antenna >> comparisons. I suppose both those would be true of most modern >> spectrum analyzers. In addition, some are quite good at determining >> the total power in a specified frequency range, and if you can find >> such a range with no signals, you can get a better reading on noise >> than you're likely able to do with an S meter, or even a narrow band >> spectral measurement. > > One of the most complex and difficult parts of a spectrum analyzer to > design is the log amp which provides this stable and precisely > logarithmic response over a wide dynamic range. There's an incredible > amount of really ingenious work on the part of some extremely talented > engineers in those circuits. In relatively recent times, Barrie Gilbert > and his folks at Analog Devices have done some equally clever work in > the design of IC log amps. It's not a trivial task by any means. And in this case, it really isn't necessary. I simply need some baseline to start my readings from. Already I have noticed that different stations come in at different strengths - presumably on the basis of propagation differences. There may be some differences over time scales of minutes also. All I need is a meter that allows me to derive a signal strength difference from two different antennas. There was a need to calibrate that. Of course, I would *love* to have a decent analyzer!! - 73 de Mike KB3EIA - Article: 221934 of rec.radio.amateur.antenna From: Owen Duffy Subject: Re: Vertical vs Horizontal shootout part one Message-ID: <27or02pjdrorgjgqq5bcirbr8tun8pr8kl@4ax.com> References: <081n025fa3l0tk3ftnb464ga44sia7h7gh@4ax.com> Date: Tue, 07 Mar 2006 19:46:35 GMT On Tue, 07 Mar 2006 14:18:47 -0500, Michael Coslo wrote: ... >>> My setup is: >>> >>> Icom IC-761 >>> Antenna 1 - Homebrew OCF dipole at ~ 50 feet. >>> Antenna 2 - Butternut HF6V -ground mounted and 18 radials on the ground. >>> >> >> Question, does the magnitude of feedline radiation from the OCF >> (presumably predominantly vertical) significantly affect qualification >> of it as a horizontal antenna? > > There shouldn't be any feedline radiationn, this is oan antenna >running coax to a 4:1 balun at the feedpoint. Mike, I understand that feedline radiation is an un-escapable characteristic of an OCF dipole, caused by the asymmetric feed. Some even claim it as a major advantage (eg Caroline Windom). Whilst no dipole is perfect in that respect, the OCF dipole is less perfect, and it may be worth modelling the thing to comment in your findings on the probably magnitude of the contribution by the feedline. Great project, look forward to follow-ups. Owen -- Article: 221935 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Current through coils References: <1141757778.043926.115850@i40g2000cwc.googlegroups.com> Message-ID: Date: Tue, 07 Mar 2006 20:13:14 GMT w8ji@akorn.net wrote: > I think it would be better if Walt represented himself, unless he ASKED > you to post that Cecil. Walt isn't presently posting for reasons of his own. He certainly gave me permission to quote his email. I will ask him if he wants to defend his statements here. > If Walt has something to say, I'm sure he will chime in. I'm sure he will if he feels so inclined. > Drumming up support by writing what we **think** others say or mean > seems pretty desperate. Those were Walt's words, not mine. (Your statement reeks of desperation, i.e. "Please don't quote any authorities who disagree with me.") > All reliable measurements I've seen disagree with Cecil's theory. Simply not true, Tom, proving once again that you don't understand what I am saying. My "theory" explains exactly why neither you nor W7EL could get the current at the ends of the coil to be equal without creating a current maximum point inside the coil. If you would just take time to understand what I am saying, you wouldn't need to utter falsehoods about what I am saying. The standing wave net current at each end of the coil is indeed the same magnitude if a current maximum or current minimum point is located inside the coil. Walter Maxwell says: "When reflections are present, a current node and a current loop can appear at separate points on an inductor simultaneously." Does that sound like constant net current through a coil? Exactly what is it about Walt's statement that you don't understand? > I can't believe anyone with experience in RF systems would think a > physically small inductor (small in terms of wavelength) would have > significantly unequal currents in the inductor or in the terminals of > the inductor, especially any difference caused by "reflected waves". A 75m bugcatcher coil is about 0.2% of a wavelength and so qualifies as "physically small". The current at each end of that coil used with an eight foot whip is nowhere near equal. I cannot believe that anyone with experience in RF systems could utter such nonsense. (That logic is a double-edged sword.) I think you and others simply didn't realize that the current in a 75m mobile bugcatcher system is almost 100% a standing wave current and now you guys are desperately trying to cover up your mistake. Others have stopped responding instead of admitting their mistake. So I ask you again: How do you explain the flow of a current whose phase is unchanging (fixed at zero degrees in a thin wire dipole). Doesn't it take a rotating phasor for current to flow? That's a simple yes/no question. What do you want to bet that it goes unanswered? Incidentally, I posted a little questionaire a couple of days ago. The response to that questionaire has been zero. Why do you reckon all the gurus are afraid to respond? -- 73, Cecil http://www.qsl.net/w5dxp Article: 221936 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Current through coils References: <1141757778.043926.115850@i40g2000cwc.googlegroups.com> Message-ID: Date: Tue, 07 Mar 2006 20:38:09 GMT w8ji@akorn.net wrote: > I think it would be better ... I forgot to ask you, Tom, why you trimmed out all the technical content from my posting and whinned about what was left? So I ask you once again: In the graphic at: http://www.qsl.net/w5dxp/qrzgif35.gif do you really expect anyone to believe that 0.1+ amp is flowing into the bottom of that coil and 0.7+ amp is flowing out of the top of the coil. If, as you say, net standing wave current actually flows, then miracles must be possible and the coil is creating energy. If, OTOH, net standing wave current just stands there then such results as reported by EZNEC are just the facts of physics. It is the forward current and reflected current that are doing the flowing and their magnitudes are indeed individually equal through the coil. -- 73, Cecil http://www.qsl.net/w5dxp Article: 221937 of rec.radio.amateur.antenna From: Gene Fuller Subject: Re: Current through coils References: <120nv3gt1f8gi3a@corp.supernews.com> <16154-440C20D8-847@storefull-3256.bay.webtv.net> <1141748066.033150.267940@v46g2000cwv.googlegroups.com> Message-ID: Date: Tue, 07 Mar 2006 21:07:52 GMT Cecil Moore wrote: [snip] > > I apologize for missing the small detail that S12 was a voltage > measurement rather than a current measurement but I'm sure you can > see how that was an honest mistake and easy to make. You didn't > mention "voltage" at all in your posting and the context was current. > I didn't recall until your objection here today that S12 is a voltage > parameter measurement. > > But that leads to a question. Why were you using voltage measurements > to try to disprove Kraus' statement about 180 degree current phase > shifting coils. Quoting from: "Antennas for All Applications", Kraus > and Marhefka, 3rd edition, page 824: "A coil (or trap) can also act > as a 180 deg (current) phase shifter as in the collinear array ... > The coil may also be thought of as a coiled-up 1/2WL element." Cecil, Interesting, The complete quote from Kraus on page 744 in my copy of his 2nd edition is: "A coil (or trap) can also act as a 180 degree phase shifter as in the collinear array of 4 in-phase lambda/2 elements in Fig. 16.30b. Here the elements present a high impedance to the coil which may be resonated without an external capacitance due to its distributed capacitance. The coil may also be though of as a coiled-up lambda/2 element." * It is possible that Kraus edited the comment in the 3rd edition, but I don't see the word "current" in this quote. It is considered good editorial form to indicate clearly when you have altered the original wording, unless you are trying to make a point, I suppose. * The coil in this case is self-resonant at the frequency of use. Do you use a self-resonant coil for your 80 meter bugcatcher? (Such a coil might be more appropriate for a pterodactyl catcher.) In any case, this has little to do with all of your rantings about loading coils. I suspect even at A&M they must have mentioned something about the characteristics of resonant circuits. * You might have noticed the prominent role of capacitance. I believe that was the item that spurred this thread. 73, Gene W4SZ Article: 221938 of rec.radio.amateur.antenna From: richardharrison@webtv.net (Richard Harrison) Subject: Re: Current through coils Date: Tue, 7 Mar 2006 16:48:54 -0600 Message-ID: <12478-440E0DD6-1189@storefull-3258.bay.webtv.net> References: Gene, W4SZ wrote: "You might have noted the prominent role of capacitance." Capacitance is one of the factors which include resistance, inductance, conductance and capacitance which determine the velocity factor and other characteristics of a transmission line or antenna. If the load at the end of this line does not match Zo, a reflection from it results. A transmission line can`t be analyzed as a simple series circuit, because the current in the wires is not everywhere the same. Neither is the voltage. To analyze the line, each unit length must be examined. Each unit length produces a phase lag in the current on its wires. The voltage lags too. This can be totaled and the interference between the incident and reflected waves deternined to find the voltage and current at any point on the transmission line, Best regards, Richard Harrison, KB5WZI Article: 221939 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Current through coils References: <12478-440E0DD6-1189@storefull-3258.bay.webtv.net> Message-ID: <2CoPf.39509$Jd.37582@newssvr25.news.prodigy.net> Date: Tue, 07 Mar 2006 23:23:42 GMT Richard Harrison wrote: > A transmission line can`t be analyzed as a simple series circuit, > because the current in the wires is not everywhere the same. Neither is > the voltage. To analyze the line, each unit length must be examined. > > Each unit length produces a phase lag in the current on its wires. The > voltage lags too. This can be totaled and the interference between the > incident and reflected waves deternined to find the voltage and current > at any point on the transmission line, Yes, and that also applies to a real-world loading coil installed in an environment of incident (forward) and reflected (backward) waves. Why this is so difficult for some people to understand is puzzling. All one has to do is use the superposition principle. Analyze the forward wave, analyze the reflected wave, and superpose the results. -- 73, Cecil http://www.qsl.net/w5dxp Article: 221940 of rec.radio.amateur.antenna From: Chris W <1qazse4@cox.net> Subject: Re: 1n21 diode housing References: <9yJOf.29654$2c4.29425@dukeread11> <2gqm021v4ec7c8t5e05dk0auohtnhv1uqu@4ax.com> Message-ID: Date: Tue, 07 Mar 2006 17:33:05 -0600 Richard Clark wrote: >On Sun, 05 Mar 2006 16:23:37 -0600, Chris W <1qazse4@cox.net> wrote: > > > >>Richard Clark wrote: >> >> >> >>>On Sun, 05 Mar 2006 09:20:20 -0600, Chris W <1qazse4@cox.net> wrote: >>> >>> >>> >>> >>> >>>>Can someone tell me where I can find the housings for a 1n21 crystal >>>>detector diode so I can hook it to some coax and a directional coupler? >>>>I can't seem to fine one anywhere >>>> >>>> >>>> >>>> >>>Try googling with: >>> 1n21 crystal mount >>> >>> >>> >>> >>A google search for that is giving me some links but still no luck >>finding a place I can buy one >> >> > >http://mailgate.supereva.com/misc/misc.industry.electronics.marketplace/msg04490.html >was at the 6th entry. > >http://store.americanmicrosemiconductor.com/1n21.html?gclid=CNbBybHzyIMCFTFZDgodfQQv8A >was at the right as a vendor > >http://www.advancedsemiconductor.com/diodes/1N/1N.shtml >sells the diodes and a call "could" result in leads > >This is a product line that is probably entirely custom design, or >salvage from equipment that is 50 years old. > >73's >Richard Clark, KB7QHC > > I saw no indication on those web sites that they sold the mounts. However, I did call them all and some others that sell the the 1N21 diodes and none sale the mounts or can tell me where to get one. -- 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: 221941 of rec.radio.amateur.antenna From: Owen Duffy Subject: Re: 1n21 diode housing Message-ID: References: <9yJOf.29654$2c4.29425@dukeread11> <2gqm021v4ec7c8t5e05dk0auohtnhv1uqu@4ax.com> Date: Tue, 07 Mar 2006 23:44:09 GMT On Tue, 07 Mar 2006 17:33:05 -0600, Chris W <1qazse4@cox.net> wrote: >> >I saw no indication on those web sites that they sold the mounts. >However, I did call them all and some others that sell the the 1N21 >diodes and none sale the mounts or can tell me where to get one. I know it is not what you asked for, but a functional replacement might be a HP crystal detector that you frequently see on Ebay for less than $100. The downside is that the consequences of destroying the diode are more expensive. Owen -- Article: 221942 of rec.radio.amateur.antenna From: Jim - NN7K Subject: Re: 1n21 diode housing References: <9yJOf.29654$2c4.29425@dukeread11> <2gqm021v4ec7c8t5e05dk0auohtnhv1uqu@4ax.com> Message-ID: Date: Tue, 07 Mar 2006 23:54:18 GMT Not to mention that - you might locate 1N21-R 's - which are Reverseable, and will leave you with the pin conductors , on BOTH ends, if you leave off the 1/4 inch cover that is swappable for the ends! And, of the mounts I have seen (they used for power out/mixer diode adaptors, for "C" band (6 GHz), they have a "N" male fitting to a "BNC" output female, BUT-- they have a wire in place from the center to the shield of the "N" end! (this for an rf choke, at 6 GHz) which would make then useless (unless you remove that jumper, buried in the male end , delicate surgury, inside the connector)! Lenkurt, Farinon, and several other outfits used these in their comm equipment! Tho, most of the plumbing I saw, had the mounts in waveguide, these MIGHT be an option, if you can locate them-- Jim NN7K Chris W wrote: > Richard Clark wrote: > >> On Sun, 05 Mar 2006 16:23:37 -0600, Chris W <1qazse4@cox.net> wrote: >> >> >> >>> Richard Clark wrote: >>> >>> >>> >>>> On Sun, 05 Mar 2006 09:20:20 -0600, Chris W <1qazse4@cox.net> wrote: >>>> >>>> >>>> >>>> >>>> >>>>> Can someone tell me where I can find the housings for a 1n21 >>>>> crystal detector diode so I can hook it to some coax and a >>>>> directional coupler? I can't seem to fine one anywhere >>>>> >>>>> >>>> >>>> Try googling with: >>>> 1n21 crystal mount >>>> >>>> >>>> >>> >>> A google search for that is giving me some links but still no luck >>> finding a place I can buy one >>> >> >> >> http://mailgate.supereva.com/misc/misc.industry.electronics.marketplace/msg04490.html >> >> was at the 6th entry. >> >> http://store.americanmicrosemiconductor.com/1n21.html?gclid=CNbBybHzyIMCFTFZDgodfQQv8A >> >> was at the right as a vendor >> >> http://www.advancedsemiconductor.com/diodes/1N/1N.shtml >> sells the diodes and a call "could" result in leads >> >> This is a product line that is probably entirely custom design, or >> salvage from equipment that is 50 years old. >> >> 73's >> Richard Clark, KB7QHC >> >> > I saw no indication on those web sites that they sold the mounts. > However, I did call them all and some others that sell the the 1N21 > diodes and none sale the mounts or can tell me where to get one. > Article: 221943 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Current through coils References: <21271-440BE4B3-805@storefull-3254.bay.webtv.net> <1141772023.638201.196770@j52g2000cwj.googlegroups.com> Message-ID: Date: Wed, 08 Mar 2006 00:08:10 GMT w8ji@akorn.net wrote: > What you are missing is the flux inside the coil links all the turns at > light speed. When it does that, current appears at nearly the same > instant of time (light speed over the spatial distance of the inductor) > in all areas that are linked by flux. I am not missing the flux linkage. What you are missing is the known phase lag that the current undergoes compared to the voltage. Whatever voltage phase shift you measured (60 degrees), the lagging current phase shift is likely to be more than double that value. Hint: an ideal inductor forces the current to lag the voltage by 90 degrees. If the current propagates at the speed of light, the voltage propagates much faster than the speed of light so it can lead the current. Please explain that one to us. > The flux coupling also tries to equalize currents throughout every area > of the coil. A well known fact. It applies to the forward current and reflected current, not to the standing wave current which is not flowing into or out of the coil at all. There is no net charge flow in a standing wave and therefore, no net current flow. At any point on a 1/2WL thin wire dipole, the only thing happening is that the energy is migrating between the H-field and the E-field. There is zero energy flow away from that point in either direction. That's why the phase angle of the reflected current is constant and fixed at zero degrees. It is simply not flowing. What is flowing is the forward and reflected component currents which indeed to obey all the rules you have listed here. > Charge conservation also dictates that any current flowing into the > coil has to be equalled by a like current flowing out the other > terminal, less any displacement currents caused by stray capacitance > (electric fields) to the outside world. Absolutely no argument here. Even assuming the coil is lossless, the magnitude of the forward current flowing into the coil is equal to the magnitude of the forward current flowing out of the coil. Likewise for the reflected current. So this part of your argument is somewhat irrelevant. What you seem to be missing is the phase shift in those component currents. > We cannot have a two terminal "black box" with confined fields that > behaves any other way, standing waves or not. If a piece of transmission that is an appreciable percentage of a wavelength is coiled into a coil that is an appreciable percentage of a wavelength, why is it surprising to you that the coil responds somewhat like the piece of wire that it replaces? The answer is that you assumed the proof in your argument. It goes something like this: A lumped inductance doesn't have any magnitude change or phase shift through the coil. A bugcatcher loading coil is a lumped inductance. Therefore, a bugcatcher loading coil doesn't have any magnitude change or phase shift through the coil. The first proof that you offered some months ago was that the lumped inductance modeled in EZNEC didn't show any magnitude change or phase shift. Do you see the fallacy in your thought processes? You assumed the proof in your argument and you are still falling into that logical trap. Is it any surprise that a software program shows no magnitude change or phase shift? Please open up your mind and think the unthinkable. You will be rewarded. > The only flaws in having zero current phase shift and zero current > difference are the less-than-perfect flux coupling and > less-than-perfect confinement of the electric field. There you go, assuming the proof in your argument. A lossless non- radiating transmission line doesn't even obey those rules. Why should you expect a real-world coil made from that transmission line wire to obey those rules? Before you respond with the 2-terminal Vs 4-terminal argument, please realize that a horizontal #14 wire 30 ft. above ground is considered to be a single-wire transmission line with a Z0 of around 600 ohms. Thus, a horizontal dipole is simply a lossy transmission line. If you would like, I can quote Balanis on all of this. > Any deviation from > following perfect two-terminal rules are directly tied to the ratio of > load impedance on the inductor to the stray capacitance to the outside > world, and of course less than perfect flux linkage from end-to-end in > the coil. Assuming the proof again. 1/4WL apart in a lossless, non-radiating transmission line, the standing wave currents are wildly different. Why are you surprised when we take that 1/4WL of wire, wind it into a coil, and achieve a lot of the same conditions? > If you can stay on topic and we process only one point at a tme, I'm > sure you will be able to learn how this works. I'm certainly game for that. We can start by agreeing that the forward current through a loading coil has the same magnitude at each end of the coil but suffers a phase shift through the coil. You measured a voltage phase shift of 60 degrees through a 100uH coil at 1 MHz. Since the current lags the voltage in a coil, the current phase shift has to have been greater than 60 degrees, maybe even 120+ degrees depending upon the Q of the coil. Tom, even I can measure the traveling wave current phase shift in a 75m bugcatcher coil so please don't insult my intelligence by asserting that a phase shift doesn't exist. If a coil could eliminate phase shifts, Intel would be using them in their computer busses. The truth is, a coil in a computer bus increases the phase shift, not decreases it. So please give us a break on that irrational concept. You have been fooled by your model. -- 73, Cecil http://www.qsl.net/w5dxp Article: 221944 of rec.radio.amateur.antenna From: Jim - NN7K Subject: Re: 1n21 diode housing References: <9yJOf.29654$2c4.29425@dukeread11> <2gqm021v4ec7c8t5e05dk0auohtnhv1uqu@4ax.com> Message-ID: Date: Wed, 08 Mar 2006 00:10:24 GMT P.S., might be worth a shot- try :Allied Communications Equipment Supply - (712) 322-2725 - 325 W South Omaha Brg Rd, Council Bluffs, IA 51501 and, inquire about a diode detector for a "LENKURT - MODEL 76 radio", a long shot, I know, but THAT was what was used to alarm low power output, in those units, and other items!! Allied specializeds in communications equipment for commercial users, especially , supplying obsolete equiptment! not cheap, but - at least they have this stuff! Jim NN7K Jim - NN7K wrote: > Not to mention that - you might locate 1N21-R 's - which are > Reverseable, and will leave you with the pin conductors , on BOTH > ends, if you leave off the 1/4 inch cover that is swappable for the > ends! And, of the mounts I have seen (they used for power out/mixer > diode adaptors, for "C" band (6 GHz), they have a "N" male fitting > to a "BNC" output female, BUT-- they have a wire in place from the > center to the shield of the "N" end! (this for an rf choke, at 6 GHz) > which would make then useless (unless you remove that jumper, buried in > the male end , delicate surgury, inside the connector)! Lenkurt, > Farinon, and several other outfits used these in their comm equipment! > Tho, most of the plumbing I saw, had the mounts in waveguide, these > MIGHT be an option, if you can locate them-- Jim NN7K > > > > > Chris W wrote: > >> Richard Clark wrote: >> >>> On Sun, 05 Mar 2006 16:23:37 -0600, Chris W <1qazse4@cox.net> wrote: >>> >>> >>> >>>> Richard Clark wrote: >>>> >>>> >>>> >>>>> On Sun, 05 Mar 2006 09:20:20 -0600, Chris W <1qazse4@cox.net> wrote: >>>>> >>>>> >>>>> >>>>> >>>>> >>>>>> Can someone tell me where I can find the housings for a 1n21 >>>>>> crystal detector diode so I can hook it to some coax and a >>>>>> directional coupler? I can't seem to fine one anywhere >>>>>> >>>>>> >>>>> >>>>> >>>>> Try googling with: >>>>> 1n21 crystal mount >>>>> >>>>> >>>>> >>>> >>>> >>>> A google search for that is giving me some links but still no luck >>>> finding a place I can buy one >>>> >>> >>> >>> >>> http://mailgate.supereva.com/misc/misc.industry.electronics.marketplace/msg04490.html >>> >>> was at the 6th entry. >>> >>> http://store.americanmicrosemiconductor.com/1n21.html?gclid=CNbBybHzyIMCFTFZDgodfQQv8A >>> >>> was at the right as a vendor >>> >>> http://www.advancedsemiconductor.com/diodes/1N/1N.shtml >>> sells the diodes and a call "could" result in leads >>> >>> This is a product line that is probably entirely custom design, or >>> salvage from equipment that is 50 years old. >>> >>> 73's >>> Richard Clark, KB7QHC >>> >>> >> I saw no indication on those web sites that they sold the mounts. >> However, I did call them all and some others that sell the the 1N21 >> diodes and none sale the mounts or can tell me where to get one. >> Article: 221946 of rec.radio.amateur.antenna From: Big Endian Subject: Q. about height of the ends of a doublet Message-ID: Date: Wed, 08 Mar 2006 00:37:20 GMT My center of a 3.8 Mhz doublet is at about 35 feet and am going to drop the ends from 30 feet to about 10 to 15 feet. Just wondering if it will make all that much difference if any? Article: 221947 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Current through coils References: <1141757778.043926.115850@i40g2000cwc.googlegroups.com> <1141772342.715920.287530@z34g2000cwc.googlegroups.com> Message-ID: Date: Wed, 08 Mar 2006 01:11:47 GMT w8ji@akorn.net wrote: > That doesn't sound like Walter gave you permission to me. He did give me permission. In a fit of anger, I made a posting that proves that fact. Upon reflection, after cooling down by taking a walk, I should not have made that posting and I have canceled it. Walter Maxwell is my friend and I don't want to drag the great man into your junk yard dog war. I respect him too much for that and regret making that posting. I just hope it didn't make it off my news-server before I canceled it. It is gone from my news-server. -- 73, Cecil http://www.qsl.net/w5dxp Article: 221948 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Current through coils References: <1141757778.043926.115850@i40g2000cwc.googlegroups.com> <1141778806.352135.21840@j52g2000cwj.googlegroups.com> Message-ID: Date: Wed, 08 Mar 2006 01:46:19 GMT w8ji@akorn.net wrote: > All personal issues and insults aside, before anyone does anything with > any of this they would have to have a good feel for how an inductor > behaves. I just asked my dog if she has a good feeling about how an inductor behaves. She wagged her tail in affirmation. Now please explain why feelings are important to this discussion. > Do you agree or disagree with my post about how an inductor behaves? I disagree with you about how an inductor behaves in a standing wave environment. I agree with Walter Maxwell who said: "If an inductance is in series with a line that has reflections, the current will NOT be the same at both ends of the inductor." Sorry about that, but Walt gave me permission to quote him. Note the emphasis on 'NOT' in his statement. A 75m bugcatcher mobile system is a *STANDING WAVE ANTENNA*, so no, I don't agree with you at all as enumerated in my previous posting. Please don't ask me the same question over and over. I am not going to change my mind until you provid valid evidence to the contrary and so far, all you have done is prove your ethics leave something to be desired. -- 73, Cecil http://www.qsl.net/w5dxp Article: 221949 of rec.radio.amateur.antenna From: Owen Duffy Subject: Re: Current through coils Message-ID: <3res02d1d1ej31mgrj8mti7fpqe4fd6621@4ax.com> References: <1141757778.043926.115850@i40g2000cwc.googlegroups.com> <1141778806.352135.21840@j52g2000cwj.googlegroups.com> Date: Wed, 08 Mar 2006 02:06:31 GMT On Wed, 08 Mar 2006 01:46:19 GMT, Cecil Moore wrote: >w8ji@akorn.net wrote: >> All personal issues and insults aside, before anyone does anything with >> any of this they would have to have a good feel for how an inductor >> behaves. > >I just asked my dog if she has a good feeling about how an inductor >behaves. She wagged her tail in affirmation. ... Oh no Cecil, not another citation! Owen -- Article: 221950 of rec.radio.amateur.antenna Date: Tue, 07 Mar 2006 20:08:39 -0600 From: Tom Ring Subject: Re: Current through coils References: Message-ID: <440e3ca7$0$7322$39cecf19@news.twtelecom.net> Hey folks, they have a word that's used occasionally that I think might be appropriate here, it is "chill". As in chill out. Things are getting more out of hand than normal. Some of you are adults, please start acting that way. Some people have been trying, possibly poorly, to be funny, forgive them. I could say more, but you get the idea. tom K0TAR Article: 221951 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Current through coils References: <440e3ca7$0$7322$39cecf19@news.twtelecom.net> Message-ID: Date: Wed, 08 Mar 2006 02:43:53 GMT Tom Ring wrote: > Some of you are adults, please start acting that way. Tom, I apologize profusely to everyone for losing my temper. I regret that every time it happens but that time never seems to be the final time. I canceled my posting made in anger. But please note that me losing my temper has absolutely no bearing on objective technical facts and has absolutely no effect at all on the validity of my technical arguments. Galileo probably lost his temper in front of the priests who placed him under house arrest. That made absolutely no difference in the scientific facts that he was asserting at the time. I am presenting my thoughts in front of the internet gurus in much the same manner as Galileo did to the priests. Hopefully, they will listen better than the priests did and not put me under house arrest. (But I have my Colt 45 ready just in case. :-) -- 73, Cecil http://www.qsl.net/w5dxp Article: 221952 of rec.radio.amateur.antenna From: richardharrison@webtv.net (Richard Harrison) Subject: Re: 1n21 diode housing Date: Tue, 7 Mar 2006 21:12:17 -0600 Message-ID: <21271-440E4B91-1080@storefull-3254.bay.webtv.net> References: Chris W., KE5GIX wrote: "Can somone tell me where O can find the housings hor a 1n21 crystal detector so I can hook it to some coax and a directional coipler?" >From the appearance of the crystal, I`d think a fuse clip and a tube socket pin could be used to make connections. Richard Clark had a good idea to look for ancient military surplus. These diodes were also prevalent in commercial microwave sets which are now long pbsolete. It reminded me I have a military TS-1268/U "Crystal Rectifier Test Set" made to test these crystals in 1945. It`s been stowed away for years, but I broke it out and tested a crystal, It uses a 1.5-volt dry-cell to measure forward and reverse currents on a meter (0-1 ma). The battery was still good and the 1n23 tested OK. It is obviously ddurable so I`m going to keep it. Maybe Fair Radio Sales or some such surplus dealer has exactly what you want. My stock of test diodes comes in lead cylinders. Best rehards, Richard Harrison, KB5WZI Article: 221953 of rec.radio.amateur.antenna From: richardharrison@webtv.net (Richard Harrison) Subject: Re: 1n21 diode housing Date: Tue, 7 Mar 2006 22:07:12 -0600 Message-ID: <21272-440E5870-229@storefull-3254.bay.webtv.net> References: <21271-440E4B91-1080@storefull-3254.bay.webtv.net> CORRECTIION The test set is a TS-268/U. Best regards, Richard Harrison, KB5WZI Article: 221954 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Current through coils References: <1141757778.043926.115850@i40g2000cwc.googlegroups.com> <1141772342.715920.287530@z34g2000cwc.googlegroups.com> Message-ID: Date: Wed, 08 Mar 2006 04:34:49 GMT w8ji@akorn.net wrote: > That doesn't sound like Walter gave you permission to me. I have backtracked to try to find out what happened. I asked Walt's permission to post the following: > Walter Maxwell wrote: >> If an inductance is in series with a line that has no reflections, >> the current will be the same at both ends of the inductor. >> >> If an inductance is in series with a line that has reflections, >> the current will NOT be the same at both ends of the inductor. >> >> Consequently, circuit analysis will not work when both forward >> and reflected currents are present in a lumped circuit. He agreed but suggested I also include his fourth statement which followed the above three statements. >> When reflections are present, a current node and a current loop >> can appear at separate points on an inductor simultaneously. When I went back to copy and paste bottom-up from his email in order to include his fourth assertion, I inadvertently copied one too many sentences at the top. It is true that I didn't have Walt's permission to publish that extra first sentence in his email. I regret that accidental mistake and wish I could take it back. And of course, neither Walt nor anyone else in the universe agrees with me 100%. But please note that accidentally including that first sentence doesn't change the technical content of Walt's other four assertions which should be allowed to stand as is until further notice. -- 73, Cecil http://www.qsl.net/w5dxp Article: 221955 of rec.radio.amateur.antenna From: "Sal M. Onella" References: Subject: Re: 3 Monos or a Tribander? Message-ID: Date: Tue, 7 Mar 2006 21:43:22 -0800 "west" wrote in message news:q7pNf.48851$g47.20547@tornado.tampabay.rr.com... > Just purchased a (tri-band 2, 1.25, .7 meters) Kenwood TH-F6A HT and was > wondering what I should use for a base antenna that will be over 60ft high > (bet I'll get tons of intermod). One thought is to purchase the best > tri-bander available or, perhaps there is too much compromise with an > all-in-one. Would you use a dual bander and a mono, which band is the dual & > which the mono or 3 monos? Of course with anything other than a tri-bander, > a triplexer will be needed. Oh what trying decisions a ham must make! Any > comments most welcomed. > > 73s > west > AF4GC > > I like j-poles, made of copper pipe. Their appeal to me is their absolute ruggedness and the freedom from any counterpoise. Just last week, I looked at my oldest one (~12 yrs) and it looked good as new except for a light patina. Aluminum would be nearly dust at that age. In addition, I have developed a method of connectorizing a j-pole that is more secure than just a single pop-rivet. On your tower, you can mount two up and one down, with the two up being the 1.25m and the 70 cm. (I think there will be the least interaction between that pair -- just a hunch.) Putting the 2m j-pole down is unlikely to hurt its pattern much; I did some informal experiments with masts near a j-pole and I had to get to less than a two-inch separation distance to affect either transmit or receive. If I can't get 1:1 as my VSWR low point, adding a cap in series with the feed usually fixes it (100pF, or so). You may not need all three antennas. A 2m j-pole is a reasonably good match at 70 cm, although the major 70 cm. lobe is not aimed at the horizon. There is radiation to the horizon, however, evidenced by the fact that I just raised a repeater on Palomar Mountain, about 42 miles to the north, using 0.5W into that durable 12 year-old copper j-pole, cut for 146 MHz. The antenna is only about 20 feet above the ground but I am clear of obstructions to the north, which helps. (At 60 ft, you will be clear of obstructions, too, you lucky devil.) The up-side of using the 2m j-pole as a dual-bander is that you can dispense with the triplexer and run two cables up the mast. The down-side of reading this far is that you now have additional choices -- not what you wanted, eh? 73, John KD6VKW Article: 221956 of rec.radio.amateur.antenna From: Owen Duffy Subject: Re: 3 Monos or a Tribander? Message-ID: <89ss02dse89v4fqvvkfmcpos8ad6eiclco@4ax.com> References: Date: Wed, 08 Mar 2006 06:11:41 GMT On Wed, 01 Mar 2006 22:21:10 GMT, "west" wrote: >Just purchased a (tri-band 2, 1.25, .7 meters) Kenwood TH-F6A HT and was >wondering what I should use for a base antenna that will be over 60ft high >(bet I'll get tons of intermod). One thought is to purchase the best >tri-bander available or, perhaps there is too much compromise with an >all-in-one. Would you use a dual bander and a mono, which band is the dual & >which the mono or 3 monos? Of course with anything other than a tri-bander, >a triplexer will be needed. Oh what trying decisions a ham must make! Any >comments most welcomed. West, Some thoughts: The economics of feedline(s) might tilt the solution in favour of a single triband antenna with LDF4-50 or better, though you will probably want a very short flylead to the handheld. (Note that the loss in 100' of RG213 at load VSWR=1.5 is 5dB at 70cm, whereas LDF4-50 is 1.5dB, and the loss in a 5' tail of RG58C/U under similar conditions is 0.7dB.) If you only want to work repeaters and your path is good enough, losses might not be an issue. (Remember though that 5W handhelds get really hot on full power.) Is LDF4-50 overkill for a handheld? It might be more appropriate than with a higher powered transmitter. If intermods are an issue (as handhelds have less than adequate front end selectivity), do the repeaters use CTCSS... at least that helps prevent the transceiver breaking mute all day and night. Does the radio have a real rx attenuator that can help with intermods, to you have sufficient rx signal strength to be able to use it? At least you are not intending using a discone. Handhelds rarely work well on external broad antennas (for intermod reasons), and even the multiband antennas can be a challenge for handhelds. Owen -- Article: 221957 of rec.radio.amateur.antenna From: "Jerry Martes" References: <5amq02tq3q0lh1ag7d724jbk55j3fj3t5b@4ax.com> Subject: Re: ferrite balun grades Message-ID: <3EuPf.5356$CT.3859@trnddc04> Date: Wed, 08 Mar 2006 06:15:27 GMT "Mike Newman" wrote in message news:sfis02hfvkc9po1855k2vbjscm0qgosiov@4ax.com... > On Tue, 07 Mar 2006 15:18:33 GMT, "Jerry Martes" > wrote: > >> >>"Mike Newman" wrote in message >>news:5amq02tq3q0lh1ag7d724jbk55j3fj3t5b@4ax.com... >>> Any advice on which grade of ferrite would be most useful for a >>> feeedline balun choke effective at 70 cm? >>> Thanks de miken zl1bnb >> >> Hi Miken >> >> I've been using the tubular, high permeability ferrites designed for RFI >>suppression slipped over the RG-223 coax for a balun for vhf antennas. I >>am >>aware of the high loss with those ferrite tubes. I have been hoping the >>high permeability would present a high reactance to currents along the >>outside of the coax. So far, the tubes are working OK for my needs. >>Your mileage may vary. >> >> Jerry >> > That's exactly what I intended doing, feeding a moxon rectangle in > this case, my win4nec model gives 50+0.1j. > > Given the correct grade of ferrite, it should probably be ok on > UHF. > > But how to to determine the effectiveness? Maybe a small bead with a > couple of turns to pick up voltage nodes on the coax feedline, with > and without the choke balun beads. > > MikeN Hi Mike Since you are acknowledging the existence of 1/10th of an ohm of inductive reactance, at UHF, you are way beyond my level of accuracy in any measurement of effectiveness. But, I once measured the inductance across the ferrite tube by connecting the impedance "meter" to the exposed ends of the coax braid that was threaded thru the center of the ferrite. Then I removed the ferrite and repeated the test with the ferrite removed. Roy Lewallen has an excellant paper written to show how to properly evaluate baluns. I have the paper saved and will be happy to share it with you. It is almost a *must read* since it is so thouough and informative. Jerry Article: 221958 of rec.radio.amateur.antenna From: Big Endian Subject: Re: Q. about height of the ends of a doublet References: <1141779448.549209.64220@j52g2000cwj.googlegroups.com> Message-ID: Date: Wed, 08 Mar 2006 09:18:40 GMT In article <1141779448.549209.64220@j52g2000cwj.googlegroups.com>, nm5k@wt.net wrote: > It will slightly decrease the performance. I'd keep the ends > as high as possible if you want the max performance. > MK I'd like to but I'm a little concerned about next door, if you know what I mean. The poles are on the lot line and in the front yard, but in the summer they are pretty well shielded by trees, in winter they stand out their naked in the wind. Article: 221959 of rec.radio.amateur.antenna From: Ken C Subject: Impedance with T-connector? Message-ID: Date: Wed, 08 Mar 2006 06:48:29 -0500 If I put a T-connector on my feedline and a 50 ohm dummy load on each leg, does the transmitter see 50 ohms, or 25 ohms? If one leg is not being used, what should be put there (if anything) for the transmitter to see 50 ohms if the impedance of the other leg is 50 ohms? Ken KC2JDY Article: 221960 of rec.radio.amateur.antenna From: richardharrison@webtv.net (Richard Harrison) Subject: Re: Bend in xmission line Date: Wed, 8 Mar 2006 06:56:44 -0600 Message-ID: <9127-440ED48C-13@storefull-3253.bay.webtv.net> References: Alfred Lorona wrote: "Conventional wisdom cautions against sharp bends in open wire transmission line." One does not want to create an impedance bump. Ed Laport shows how to make right-angle turns. See page 396 of "Radio Antenna Engineering". It works fine with 100 KW. Best regards, Richard Harrison, KBB5WZI Article: 221961 of rec.radio.amateur.antenna From: "Dale Parfitt" References: <1141820228.146191.318710@j33g2000cwa.googlegroups.com> Subject: Re: Impedance with T-connector? Message-ID: Date: Wed, 08 Mar 2006 13:17:07 GMT "Jim" wrote in message news:1141820228.146191.318710@j33g2000cwa.googlegroups.com... > > Ken C wrote: >> If I put a T-connector on my feedline and a 50 ohm dummy load on each >> leg, does the transmitter see 50 ohms, or 25 ohms? >> >> If one leg is not being used, what should be put there (if anything) >> for the transmitter to see 50 ohms if the impedance of the other leg >> is 50 ohms? >> >> Ken KC2JDY > > Ken; > > 50 ohms. > > Jim > I'd be interested in seeing your thinking on this. Dale W4OP Article: 221962 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Current through coils References: <1141757778.043926.115850@i40g2000cwc.googlegroups.com> <1141778806.352135.21840@j52g2000cwj.googlegroups.com> <1141812993.768076.158930@e56g2000cwe.googlegroups.com> Message-ID: Date: Wed, 08 Mar 2006 13:36:45 GMT w8ji@akorn.net wrote: > Then we can't go further with this Cecil, ... That's simply not true. We can take this discussion to its logical conclusion if you are not afraid to continue it in logical order at a logical starting point. Starting with coils is like looking for your keys under the street light, instead of where you lost them, because that's where the light is better. Coil theory is not the problem. Standing wave current theory is the problem. Let's discuss the problem. > If you refuse to discuss the behavior or electrical characteristics of > the component you are talking about, there really isn't anything we can > talk about. I'm not refusing to discuss anything as long as it is taken in logical order. Our disagreement extends much farther back into fundamental technical principles than just the subject of coil function. We actually may have no technical disagreement about coils. I believe our basic disagreement involves standing wave current, not coils, so standing wave current should be the topic of this initial discussion. For that, we need to first agree on the 1/2WL thin wire model of a dipole. Let's see what we can agree on. Can we agree on the following pertaining to a 1/2 wavelength thin wire dipole? The net current in a standing wave antenna is a standing wave. The net current displayed by EZNEC for a standing wave antenna is a standing wave. The net standing wave current is the phasor sum of the forward current traveling wave and the reflected current traveling wave. The principle of superposition applies to the two component waves. If we superpose the forward current traveling wave and the reflected current traveling wave, we obtain the net standing wave current. Let's take for instance, that 1/2WL thin wire dipole. The standing wave current distribution and phase appears in Figure 14-2 in Kraus and Figures 1.15 and 4.8 in Balanis. If the current at the feedpoint is 1 amp, the net standing wave current equals cosine(x) where 'x' is the distance in degrees away from the feedpoint. This topic of discussion will most likely reveal that our fundamental point of disagreement is standing wave current and not coils at all. So which points above do you agree/disagree with? References to Kraus are from "Antennas for All Applications", Kraus and Marhefka, 3rd edition. References to Balanis are from "Antenna Theory", Balanis, 2nd edition. -- 73, Cecil http://www.qsl.net/w5dxp Article: 221963 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Current through coils References: <1141757778.043926.115850@i40g2000cwc.googlegroups.com> <1141778806.352135.21840@j52g2000cwj.googlegroups.com> <1141812993.768076.158930@e56g2000cwe.googlegroups.com> <6hNpk4NyLsDEFAnW@ifwtech.co.uk> Message-ID: Date: Wed, 08 Mar 2006 13:49:45 GMT Ian White GM3SEK wrote: > And also, if the inductively loaded antenna is designed by the "antenna > as transmission line" method (as used by Boyer and ON4UN for example) it > clearly shows that the loading inductance is simply there to cancel the > net capacitive reactance - in other words, it behaves in exactly the > same way as you would in any other circuit. If that is true, you guys shouldn't have any difficulty proving me wrong and sending me back to the woodshed once and for all. If the above is not entirely true, please don't put me under house arrest until I present the truth as I see it. And certainly, call me on anything that is wrong. If you will keep listening with an open mind, I think I can show you that the words, "clearly", "simply", and "exactly", in your above statement are not entirely correct. -- Ian, no one has explained the antenna currents reported by EZNEC at: http://www.qsl.net/w5dxp/qrzgif35.gif How can 0.1+ amp of current be 'flowing' into the bottom of the coil and 0.7+ amp of current be 'flowing' out of the top of the coil. It's been days now and no one has offered an explanation. -- 73, Cecil http://www.qsl.net/w5dxp Article: 221964 of rec.radio.amateur.antenna From: Michael Coslo Subject: Re: Non-theoretical, practical and probably stupid question Date: Wed, 08 Mar 2006 09:31:44 -0500 Message-ID: References: <54f81$440893e2$42a1bfc2$25389@FUSE.NET> <87u0afnuui.fsf@qmc.ph.msstate.edu> tclay@qmc.ph.msstate.edu wrote: >> It seems necessary to "waste" as much as 60 feet of rope in either >> side. If I support the center insulator, then double that. >> >> Is there a better way? > > I'm not sure what the problem is, yes, it takes a bunch of rope if > you can't climb the tree. > > I usually don't bother with pulleys as I prefer to get the antenna > up as high as possible. You will lose 15-20 feet of height (or more) > using a pulley compared to not. Hi Tor, I don't use pulleys either, but I'm not sure I uunderstand why you would lose height with them. - 73 de Mike KB3EIA - Article: 221965 of rec.radio.amateur.antenna From: Michael Coslo Subject: Re: Vertical vs Horizontal shootout part one Date: Wed, 08 Mar 2006 09:47:18 -0500 Message-ID: References: <081n025fa3l0tk3ftnb464ga44sia7h7gh@4ax.com> <818s029289valqofpmkpvp2qghuedqrd83@4ax.com> Richard Clark wrote: > On Tue, 07 Mar 2006 14:18:47 -0500, Michael Coslo > wrote: > >>> Question, does the magnitude of feedline radiation from the OCF >>> (presumably predominantly vertical) significantly affect qualification >>> of it as a horizontal antenna? >> There shouldn't be any feedline radiationn, this is oan antenna >> running coax to a 4:1 balun at the feedpoint. > > Hi Mike, > > Not all 4:1 BalUns exhibit enough (or sometimes any) common mode Z. Okay. Perhaps I might better characterize my experiment as a comparison of a vertical and an OCF dipole of indeterminate vertical vs horizontal performance. I was under the impression from the designers of this flavor of dipole that they were not radiating from the feedline unless you wanted that "feature". In that case you would feed the antenna with balanced line. Certainly the antenna doesn't seem to be radiating RF >from anywhere but the antenna bits. p.s. forgive the spelling, I am using a beta of Thunderbird for my newsgroups, and it seems to have a few quirks that make it hard to see what I have written!! - 73 de Mike KB3EIA - Article: 221966 of rec.radio.amateur.antenna From: "Reg Edwards" Subject: Re: Current through coils Date: Wed, 8 Mar 2006 15:22:08 +0000 (UTC) Message-ID: References: <440e3ca7$0$7322$39cecf19@news.twtelecom.net> <1141823025.751401.183670@j33g2000cwa.googlegroups.com> Has it ever occurred to you guys that a coil is a coil wherever it is used and always behaves in the same way. Article: 221967 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Current through coils References: <440e3ca7$0$7322$39cecf19@news.twtelecom.net> <1141823025.751401.183670@j33g2000cwa.googlegroups.com> Message-ID: <6PDPf.44803$Jd.43007@newssvr25.news.prodigy.net> Date: Wed, 08 Mar 2006 16:41:38 GMT Cecil Moore wrote: > Reg Edwards wrote: >> Has it ever occurred to you guys that a coil is a coil wherever it is >> used and always behaves in the same way. > > The coil always behaves in the same way. Unfortunately, the models > used to explain the operation of the coil don't work in the same > way. Please see: > > http://www.ttr.com/corum/index.htm Dang Reg, I forgot to post the quote from that web page. Here it is: "Lumped element representations for coils require that the current is uniformly distributed along the coil - no wave interference and no standing waves can be present on lumped elements." Therefore, lumped element representations for coil CANNOT be used to analyze standing wave antennas. I wasn't the first to say that. Using a lumped element representation for a coil in a standing wave environment is "assuming the proof". Here's more information along those same lines. http://www.ttr.com/TELSIKS2001-MASTER-1.pdf -- 73, Cecil http://www.qsl.net/w5dxp Article: 221968 of rec.radio.amateur.antenna From: richardharrison@webtv.net (Richard Harrison) Subject: Re: Current through coils Date: Wed, 8 Mar 2006 11:14:18 -0600 Message-ID: <18782-440F10EA-9@storefull-3252.bay.webtv.net> References: Reg Edwards wrote: "Has it ever occurred to you guys that a coil is a coil however it is used and always behaves in the same way?" Yes! But when it is part of an antenna system, the system imposes energy upon the coil in ways which the coil does not control. "The system is the solution", AT&T used to say. John D. Kraus writes on page 176 of his 1950 edition of "Antennas": "The term transmission mode is used to describe the manner in which an electromagnetic wave is propagated along an infinite helix (that`s a coil, right?) as though the helix constituted an infinite transmission line or wave guide." Wave guides and transmission lines are subject to reflections. These produce the standing wave patterns exhibited in many text books. Kraus uses the helix very generally. To him it can collapse to a single loop or be stretched to a straight wire. When a "normal mode" helix (coil) is used as part of a antenna system, It radiates normal to the axis of the coil, similar to the manner it would were it stretched out to a straight wire. A reflection within the antenna system would return energy toward the generator, similar to the manner it would with straight wires. The same sort of interaction between incident and reflected waves must occur. There is no other way. These produce variatiations in both current and voltage in a periodic manner along the helix as described for transmission lines which should be familiar to all. The whole section of helical antennas in Kraus is interesting. Kraus is the inventor of the Axial mode helical antenna. I think he tells the story in his 3rd edition of how he went home and wound one up and tested it after being told by an expert of the times that such an antenna was impossible. Best regards, Richard Harrison, KB5WZI Article: 221969 of rec.radio.amateur.antenna From: "Reg Edwards" Subject: Re: Current through coils Date: Wed, 8 Mar 2006 18:41:58 +0000 (UTC) Message-ID: References: <440e3ca7$0$7322$39cecf19@news.twtelecom.net> <1141823025.751401.183670@j33g2000cwa.googlegroups.com> "Ian White GM3SEK" wrote > Reg Edwards wrote: > >Has it ever occurred to you guys that a coil is a coil wherever it is > >used and always behaves in the same way. > > > > > That is only true if you say it about pure inductance. > ======================================== Ian, old boy, you are no better than the rest of the gaggle ! There's not one of the clever buggers who can design a coil-loaded whip for a given frequency using a pencil, paper and a pocket calculator. They have to copy an already existing, pre-tested, model after searching through the antenna comics. --- Reg. Article: 221970 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Current through coils References: <1141757778.043926.115850@i40g2000cwc.googlegroups.com> <1141778806.352135.21840@j52g2000cwj.googlegroups.com> <1141812993.768076.158930@e56g2000cwe.googlegroups.com> <6hNpk4NyLsDEFAnW@ifwtech.co.uk> Message-ID: <3CFPf.26960$2O6.9927@newssvr12.news.prodigy.com> Date: Wed, 08 Mar 2006 18:44:15 GMT Ian White GM3SEK wrote: > There is one typo in that statement: I posted it part-way through > changing from "In other words, you use the inductance in exactly the > same way as you would in any other circuit" to "In other words, it [the > inductance] behaves in exactly the same way as it does in any other > circuit". I stand by both of those statements. Too bad you are standing by false statements. :-) Quoting: http://www.ttr.com/corum/index.htm "... one needs transmission line analysis (or Maxwell's equations) to model these electrically distributed structures. Lumped circuit theory fails because it's a theory whose presuppositions are inadequate. Every EE in the world was warned of this in their first sophomore circuits course." Seems you weren't listening that day, Ian. "Lumped element representations for coils require that the current is uniformly distributed along the coil - no wave interference and no standing waves can be present on lumped elements." > It's because you modeled a real-life coil, whose length and diameter are > each a significant fraction of the size of the whole antenna. A 75m bugcatcher coil is a real-life coil, Ian. Contrary to what W8JI asserts, it is a significant fraction of the size of the whole antenna. It uses 42 feet of wire, for goodness sake. > You are hung up on something far more fundamental. You are > misrepresenting the fundamental electrical properties of inductance to > make them fit your theory. I am using distributed network theory known to work in a standing wave environment. You are using lumped element theory known to fail in a standing wave environment. A 75m bugcatcher mobile antenna is a standing wave environment. So exactly who is "misrepresenting the fundamental electrical properties of inductance to make them fit his theory"? -- 73, Cecil http://www.qsl.net/w5dxp Article: 221971 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: OT for Cecil or any other ex RRAPers References: <1141756042.224852.90540@j52g2000cwj.googlegroups.com> <1141837212.960395.167340@j52g2000cwj.googlegroups.com> Message-ID: Date: Wed, 08 Mar 2006 18:45:27 GMT an_old_friend wrote: > well thanks for responding if you ha[en to remmber (after all I might > have just started your memory moving) :-) My memory moved out a few years ago. :-) -- 73, Cecil http://www.qsl.net/w5dxp Article: 221972 of rec.radio.amateur.antenna From: "AAA RF Products" Subject: FS: RF Connectors & Adapters Message-ID: <1QFPf.2813$ld2.2727@fed1read11> Date: Wed, 8 Mar 2006 11:00:28 -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: 221973 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Current through coils References: <1141757778.043926.115850@i40g2000cwc.googlegroups.com> <1141778806.352135.21840@j52g2000cwj.googlegroups.com> <1141812993.768076.158930@e56g2000cwe.googlegroups.com> <6hNpk4NyLsDEFAnW@ifwtech.co.uk> <7aKdnd_JhqWDjpLZnZ2dnUVZ_smdnZ2d@comcast.com> Message-ID: Date: Wed, 08 Mar 2006 19:04:02 GMT Amos Keag wrote: > I agree with Cecil. Good to hear. > Conclusion: the coil, at 75 degrees of the circuit, has to be treated > differently from DC or LF models. Yes, I just ran an experiment that would support that statement. My 75m bugcatcher coil is mounted on a one foot bottom section on my pickup. I'm sorry but I can't fasten the coil directly to the mount for reasons of clearance. But one foot at 75m is only about 1.5 degrees so let's call it negligible. I have one of those 12 foot telescoping whips from MFJ. It's great for portable operation from my pickup. It is adjustable >from 2 feet to 12 feet. The first measurement I made was with no whip at all, just the bugcatcher sitting on top of a one foot bottom section. I used an MFJ-259B for the measurements connected through a two foot W2DU choke. Here are the results. resonant Stinger frequency 0' 6.7 MHz 2' 5.1 MHz 4' 4.3 MHz 6' 3.8 MHz 8' 3.5 MHz 10' 3.2 MHz 12' 3.0 MHz It's more than obvious that with a stinger length of 0', the coil is very close to 1/4WL and is NOT a lumped inductance. The current at the top of the coil is obviously zero. So moving down the frequency in 2' increments, exactly when does a coil made with 42 feet of wire become a lumped inductance in the presence of standing waves? http://www.ttr.com/corum/index.htm says never. When I get my MFJ current meter, I will actually measure the current at the top and bottom of the coil. -- 73, Cecil http://www.qsl.net/w5dxp Article: 221974 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Current through coils References: <440e3ca7$0$7322$39cecf19@news.twtelecom.net> <1141823025.751401.183670@j33g2000cwa.googlegroups.com> Message-ID: <9WFPf.26966$2O6.2887@newssvr12.news.prodigy.com> Date: Wed, 08 Mar 2006 19:05:41 GMT Reg Edwards wrote: > There's not one of the clever buggers who can design a coil-loaded > whip for a given frequency using a pencil, paper and a pocket > calculator. Sure we can, Reg. Just design the coil too big and jumper the un-needed turns. :-) -- 73, Cecil http://www.qsl.net/w5dxp Article: 221975 of rec.radio.amateur.antenna From: "NA" Subject: Military ships fan antenna Message-ID: <_1GPf.17539$992.17494@tornado.socal.rr.com> Date: Wed, 08 Mar 2006 19:14:02 GMT Can anyone tell me about "fan antennas" like those used on the large navy ships. Thanks Jim N6PJQ Article: 221976 of rec.radio.amateur.antenna From: Roy Lewallen Subject: Re: Vertical vs Horizontal shootout part one Date: Wed, 08 Mar 2006 11:18:28 -0800 Message-ID: <120ubgbo1kpf523@corp.supernews.com> References: <081n025fa3l0tk3ftnb464ga44sia7h7gh@4ax.com> <818s029289valqofpmkpvp2qghuedqrd83@4ax.com> Michael Coslo wrote: > Okay. Perhaps I might better characterize my experiment as a > comparison of a vertical and an OCF dipole of indeterminate vertical vs > horizontal performance. I was under the impression from the designers of > this flavor of dipole that they were not radiating from the feedline > unless you wanted that "feature". Unfortunately, even if the designers don't intend the feedline to radiate, it's very difficult to avoid. A single balun at the feedpoint is very likely not enough to prevent it. In that case you would feed the > antenna with balanced line. That would make no difference at all in determining whether or not the line would radiate. Certainly the antenna doesn't seem to be > radiating RF from anywhere but the antenna bits. The amount of feedline common mode current and therefore radiation will vary from band to band, probably a great deal. It's easy enough to make up a simple current probe with a clamp-on core and make quantitative measurements if you're interested. They've been described on this newsgroup several times. Roy Lewallen, W7EL Article: 221977 of rec.radio.amateur.antenna From: Owen Duffy Subject: Re: Impedance with T-connector? Message-ID: References: Date: Wed, 08 Mar 2006 19:35:42 GMT On Wed, 08 Mar 2006 06:48:29 -0500, Ken C wrote: >If I put a T-connector on my feedline and a 50 ohm dummy load on each >leg, does the transmitter see 50 ohms, or 25 ohms? Not necessarily either. The T connects the branches in parallel, so if you have a 50+j0 load and any length of 50 ohm coax connected to each of two branches, the impedance at the T is 25 ohms. If you connect to T to something else (eg a transmitter) with 50 ohm coax, the SWR on that section will result in impedance transformation that depends on the coax (vf), frequency, and length. For example, if you had 3m of RG58C/U at 7MHz, the impedance looking into the cable would be 36+j24. You can solve the transmission line transformation with the calculator at http://www.vk1od.net/tl/tllce.php . >If one leg is not being used, what should be put there (if anything) >for the transmitter to see 50 ohms if the impedance of the other leg >is 50 ohms? You know the answer to that now, the branches of the T are in parallel, leave one branch open circuit. Owen -- Article: 221978 of rec.radio.amateur.antenna From: "Reg Edwards" Subject: Re: Vertical vs Horizontal shootout part one Date: Wed, 8 Mar 2006 21:55:42 +0000 (UTC) Message-ID: References: <081n025fa3l0tk3ftnb464ga44sia7h7gh@4ax.com> <818s029289valqofpmkpvp2qghuedqrd83@4ax.com> <120ubgbo1kpf523@corp.supernews.com> Radiation from feedlines is grossly exaggerated. For many purposes, practically it does not occur. When discussing the importance of such radiation one should always crudely estimate its level relative to transmitter or radiated power. If you don't know what its level is then you don't know what you are waffling about. ---- Reg. Article: 221979 of rec.radio.amateur.antenna From: "Reg Edwards" Subject: Re: Current through coils Date: Wed, 8 Mar 2006 21:55:42 +0000 (UTC) Message-ID: References: <440e3ca7$0$7322$39cecf19@news.twtelecom.net> <1141823025.751401.183670@j33g2000cwa.googlegroups.com> <9WFPf.26966$2O6.2887@newssvr12.news.prodigy.com> "Cecil Moore" wrote > Reg Edwards wrote: > > There's not one of the clever buggers who can design a coil-loaded > > whip for a given frequency using a pencil, paper and a pocket > > calculator. > > Sure we can, Reg. Just design the coil too big and > jumper the un-needed turns. :-) ========================================== Dear Cecil, you know as well as I do, that pruning the coil is not DESIGN. It is a procedure done by people who are floundering about in the dark. Not by supposedly professionally qualified engineers who are participating in this discussion. Anybody, even a CB-er, can make an antenna with the top of the whip a mile long and then severely prune it until the antenna resonates at the pre-determined frequency, following a score of attempts to use coils of different dimensions and numbers of turns. But even the experimenting CB-er has to understand what he is doing. Not so the so-called professionals. It appears from this discussion the university-educated Ph.D professionals are the ones who are floundering about in the dark. Silly old-wives indeed. As I have said before, the standards of education in Western schools and universities are dropping to bits. Chinese, Japanese, Korean, Iraqian, Iranian, Afganistan, Indian, Pakistan, Vietnam and Indianesian school kids, not forgetting the half-starved sewer-rats of Rio-de-Janerio, are better at arithmetic. And, what is more important, what stems from it! If you are interested I am on Spanish, Valencia Red tonight. It is supposed to minimise cholesterol in the blood stream. ---- Your old pal, Reg. Article: 221980 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Current through coils References: <440e3ca7$0$7322$39cecf19@news.twtelecom.net> <1141823025.751401.183670@j33g2000cwa.googlegroups.com> <9WFPf.26966$2O6.2887@newssvr12.news.prodigy.com> Message-ID: <9CIPf.74513$PL5.63379@newssvr11.news.prodigy.com> Date: Wed, 08 Mar 2006 22:09:09 GMT Reg Edwards wrote: > Dear Cecil, you know as well as I do, that pruning the coil is not > DESIGN. I dunno about that, Reg. The Texas Bugcatcher guy made a living off of coils that were designed to require pruning. He even sold a pruning kit. > If you are interested I am on Spanish, Valencia Red tonight. It is > supposed to minimise cholesterol in the blood stream. Muy bueno. California Merlot here. Makes me forget about my cholesterol. :-) -- 73, Cecil http://www.qsl.net/w5dxp Article: 221981 of rec.radio.amateur.antenna From: Skipp sent this Subject: yahoo rf amplifiers group Date: Wed, 8 Mar 2006 22:25:25 +0000 (UTC) Message-ID: Just a 50 cent plug to let you folks know about the Yahoo RF Amplifiers Group, please feel free to join in if you have an interest in rf and audio amplifiers. Building - construction - operation - design - operation, you get the idea. Hope to see you there... http://groups.yahoo.com/group/rfamplifiers/ cheers, skipp Article: 221982 of rec.radio.amateur.antenna Date: Wed, 08 Mar 2006 16:46:51 -0600 From: Tom Ring Subject: Re: Q. about height of the ends of a doublet References: Message-ID: <440f5f05$0$3762$39cecf19@news.twtelecom.net> Dave Oldridge wrote: > This won't make it into a superior DX antenna but it may allow you to hear > things you missed before. Basically, Bob Heinlein was right. There ain't > any such thing as a free lunch. > TANJ! Tom K0TAR Article: 221983 of rec.radio.amateur.antenna From: rocky Subject: Re: Q. about height of the ends of a doublet References: Message-ID: Date: Wed, 08 Mar 2006 23:23:56 GMT In article , Dave Oldridge wrote: > Big Endian wrote in > news:nospam-3801D8.18373207032006@news-rdr-02.rdc-kc.rr.com: > > > > > My center of a 3.8 Mhz doublet is at about 35 feet and am going to > > drop the ends from 30 feet to about 10 to 15 feet. Just wondering if > > it will make all that much difference if any? > > There will be a marked improvement in the low angle performance in the > direction off the ends of the antenna (the flattop is very poor at this). > This will come at the expense of a sight loss (about .8db) off the > pattern's top (where you can most afford it). You will also experience a > slight deterioration in the SWR (based on 50 ohm coax) from about 1.34 to > 2.05, easily managed by any tuner, including those built into many radios. > You will also find that you need to shorten the antenna very slightly to > maintain the same resonant frequency. > > This won't make it into a superior DX antenna but it may allow you to hear > things you missed before. Basically, Bob Heinlein was right. There ain't > any such thing as a free lunch. What I've read is that when the ends are dropped to an inverted Vee configuration the feedpoint impedance drops closer to 50 ohms, but the Vee bandwidth is more restricted. Hard to believe that lowering the ends by 15 feet from 30 would make all that much difference on 75 meters. Tnx Article: 221984 of rec.radio.amateur.antenna From: "west" Subject: SMA Connector Follow up Message-ID: Date: Thu, 09 Mar 2006 00:04:53 GMT Originally I requested a source for various length of cables with SMA Male on one end to plug into a HT (Kenwood TH-F6A) and the other end a PL-259. Lengthy and comprehensive treads soon made me realize that the PL-259 would be ill advised especially at UHF & higher. So I found some ready made cables with SMA and N connectors. The only problem (if it's really a problem) is those skinny cables they come in. Some claim that they are 50 ohms, another RG-174. I don't know the other types. Do you think it will be alright to use those narrow cables from my HT to an amplifier to my monitoring meter and then use regular RG 8 to the base antenna? Will those skinny cables present some kind of mismatch. You know it's almost impossible to solder a SMA connector to an RG 8. Thoughts, please? Thank you. Cordially, west AF4GC Article: 221985 of rec.radio.amateur.antenna From: dplatt@radagast.org (Dave Platt) Subject: Re: SMA Connector Follow up Date: Thu, 09 Mar 2006 00:47:50 -0000 Message-ID: <120uupmt5ovbdb8@corp.supernews.com> References: In article , west wrote: >Originally I requested a source for various length of cables with SMA Male >on one end to plug into a HT (Kenwood TH-F6A) and the other end a PL-259. >Lengthy and comprehensive treads soon made me realize that the PL-259 would >be ill advised especially at UHF & higher. So I found some ready made cables >with SMA and N connectors. The only problem (if it's really a problem) is >those skinny cables they come in. Some claim that they are 50 ohms, another >RG-174. RG-174 is a 50-ohm cable, just over 1/10" in diameter. It's a decent choice for HT-to-whatever pigtails, at long as the length isn't so great that losses become unacceptable. > I don't know the other types. Do you think it will be alright to use >those narrow cables from my HT to an amplifier to my monitoring meter and >then use regular RG 8 to the base antenna? Almost certainly for short lengths. I wouldn't use it for long runs. The attenuation per 100' of RG-174 is around 13 dB at 146 MHz, and about twice that at 440. Thus, at 440, 10' of the cable would lose you around 2.5 dB, or less than 1/2 of an S-unit at the conventional calibration. This loss would occur for both transmission and reception. There are other cables of this size which are less lossy - LMR-100A has approximately half as much signal loss per foot. Both RG-174 and LMR-100A have solid center conductors, and might not stand up to a very large number of flexing cycles. A cable of similar size with a multistrand center conductor might live longer. > Will those skinny cables present >some kind of mismatch. Not unless the manufacture is seriously botched (e.g. cable not soldered to connector correctly). They're the same impedance as RG-8, but are a lot more lossy. > You know it's almost impossible to solder a SMA >connector to an RG 8. Thoughts, please? Thank you. Go for it. A pigtail of anywhere from 18" to a few feet should act as a perfectly acceptable strain-relief for your HT's SMA connector, and even at 440 its loss should be low enough that you'd be unlikely to notice it. -- Dave Platt AE6EO Hosting the Jade Warrior home page: http://www.radagast.org/jade-warrior I do _not_ wish to receive unsolicited commercial email, and I will boycott any company which has the gall to send me such ads! Article: 221986 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Current through coils References: <1141757778.043926.115850@i40g2000cwc.googlegroups.com> <1141778806.352135.21840@j52g2000cwj.googlegroups.com> <1141812993.768076.158930@e56g2000cwe.googlegroups.com> <6hNpk4NyLsDEFAnW@ifwtech.co.uk> <7aKdnd_JhqWDjpLZnZ2dnUVZ_smdnZ2d@comcast.com> <1141864325.153022.145680@p10g2000cwp.googlegroups.com> Message-ID: Date: Thu, 09 Mar 2006 02:32:00 GMT w8ji@akorn.net wrote: > Thinking the inductor or loading coil represents 60 degrees of > electrical length is EXACTLY where the big myth is at, and it can > easily be proven to be a myth! Well then do it, Tom. But you are not allowed to use the lumped circuit model. You must use the distributed network model (or Maxwell's equations). I think the distributed network model proves otherwise. Could be you are the one spreading myths after using an invalid model. There's just no getting around it. The forward current undergoes approximately a 90 degree phase shift from the feedpoint to the end of a 75m mobile bugcatcher antenna. It is reflected there (180 degree phase shift) and becomes reflected current which undergoes approximately a 90 degree phase shift from the tip of the antenna back to the feedpoint. So from the start of the forward current wave to the return of the reflected current wave there is approximately a 360 degree shift in order to put the forward current and reflected current in phase so they can superpose constructively. If the straight element part of the antenna is 12 degrees, we can account for 12 + 180 + 12 = 204 degrees without the coil. The coil is the only other thing in the whole system. Where does the other 78+78=156 degrees of total phase shift come from if not from the coil? I've explained all of this to you many times. Might be a good time to start listening. You can prove this for yourself. Using current probes and your o'scope you can measure the traveling wave phase shift through a loading coil. That figure is approximately the electrical length that is replaced by the coil when it is installed in the antenna. -- 73, Cecil http://www.qsl.net/w5dxp Article: 221987 of rec.radio.amateur.antenna From: richardharrison@webtv.net (Richard Harrison) Subject: Re: Current through coils Date: Wed, 8 Mar 2006 23:37:57 -0600 Message-ID: <18782-440FBF35-53@storefull-3252.bay.webtv.net> References: <1141864325.153022.145680@p10g2000cwp.googlegroups.com> Tom, W8JI wrote: "Thinking the inductor or loading coil represents 60 degrees of electrical length is EXACTLY where the big myth is at and it can easily be proven to be a myth!" A vertical antenna is often driven against a reflecting ground system. It is desirable that it be self resonant at nearly 1/4-wavelength (90-degrees), in many instances, to eliminate reactive impedance to current into the antenna, avoid loading coil loss, and avoid bandwidth limitation which comes with high-Q coils. Even with its drawbacks, a base loading coil is often the practical way to resonate a too-short antenna. Suppose the vertical is only 2/3 the height needed for self resonance, or 60-degrees high. The loading coil must replace about 30-degrees of missing antenna to bring the vertical to resonance. 30-degrees is not an inductance value. An inductor is impure because it has resistance and capacitance in addition to inductance. Also, the inductance needed to replace the missing 30-degrees of antenna depends on where it is sited, high, low, or in-between. Siting affects performance as it determines current distribution along the antenna. Where is the myth? Best regards, Richard Harrison, KB5WZI Article: 221988 of rec.radio.amateur.antenna From: SamSvL Subject: Re: FS: RF Connectors & Adapters Date: 9 Mar 2006 09:03:32 GMT Message-ID: References: <1QFPf.2813$ld2.2727@fed1read11> "AAA RF Products" wrote in news:1QFPf.2813 $ld2.2727@fed1read11: > 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. > > No shipping to Europe? Article: 221989 of rec.radio.amateur.antenna From: SamSvL Subject: Re: SMA Connector Follow up Date: 9 Mar 2006 09:06:13 GMT Message-ID: References: You know it's almost impossible to solder a SMA connector to > an RG 8. Thoughts, please? Thank you. > > Cordially, > west > AF4GC > I found on Ebay reasonable priced SMA to N adapters. Might save you from mounting a small connector on a thick cable! sam Article: 221990 of rec.radio.amateur.antenna From: Owen Duffy Subject: Re: SMA Connector Follow up Message-ID: <2gtv02tb0755vgq9qvr30eaf80pi6cqr91@4ax.com> References: Date: Thu, 09 Mar 2006 09:40:54 GMT On Thu, 09 Mar 2006 00:04:53 GMT, "west" wrote: >Originally I requested a source for various length of cables with SMA Male >on one end to plug into a HT (Kenwood TH-F6A) and the other end a PL-259. >Lengthy and comprehensive treads soon made me realize that the PL-259 would >be ill advised especially at UHF & higher. So I found some ready made cables >with SMA and N connectors. The only problem (if it's really a problem) is >those skinny cables they come in. Some claim that they are 50 ohms, another >RG-174. I don't know the other types. Do you think it will be alright to use >those narrow cables from my HT to an amplifier to my monitoring meter and >then use regular RG 8 to the base antenna? Will those skinny cables present >some kind of mismatch. You know it's almost impossible to solder a SMA >connector to an RG 8. Thoughts, please? Thank you. West, I would be thinking about a tail made from LMR-195. It is a low loss cable, dimesionally compatible with RG58 connectors. One meter of it has a loss of 0.25dB at 440MHz. Nobody solders these things do they? Get a hold of crimp UHF and SMA connectors suitable for RG58 and borrow a crimp tool to make them up. Might be worth buying a couple of strain relief boots as well. Alternatively, get a bit of old cellular cable, but it may have a solid centre conductor... check it out. Keep in mind that a run of 30m of RG8 has a loss close to 5dB at 440MHz, ie only 30% of the transmitter power reaches the feedpoint. Owen -- Article: 221991 of rec.radio.amateur.antenna From: "Reg Edwards" Subject: Re: Vertical vs Horizontal shootout part one Date: Thu, 9 Mar 2006 10:15:23 +0000 (UTC) Message-ID: References: <081n025fa3l0tk3ftnb464ga44sia7h7gh@4ax.com> <818s029289valqofpmkpvp2qghuedqrd83@4ax.com> <120ubgbo1kpf523@corp.supernews.com> "Mike Coslo" wrote > Reg Edwards wrote: > > Radiation from feedlines is grossly exaggerated. > > Hi Reg, I can't see who you are replying to - a line of quote would be > wunnerful. 8^) ========================================= I'm not replying to anyone in particular. Just to anybody who discusses power radiated from feedlines. ========================================= > > > For many purposes, practically it does not occur. > > > > When discussing the importance of such radiation one should always > > crudely estimate its level relative to transmitter or radiated power. > > Is there any way of doing that? ========================================== Mike, you'd better ask that from people who discuss power radiated >from feedlines. They ought to know! ---- Reg. Article: 221992 of rec.radio.amateur.antenna From: "Reg Edwards" Subject: Re: Vertical vs Horizontal shootout part one Date: Thu, 9 Mar 2006 10:15:23 +0000 (UTC) Message-ID: References: <081n025fa3l0tk3ftnb464ga44sia7h7gh@4ax.com> <818s029289valqofpmkpvp2qghuedqrd83@4ax.com> <120ubgbo1kpf523@corp.supernews.com> Danny, Since I am not fluent in Latin, could you please tell me what is a "Factoid"? ---- Reg. Article: 221993 of rec.radio.amateur.antenna From: "Reg Edwards" Subject: Re: Current through coils Date: Thu, 9 Mar 2006 11:03:24 +0000 (UTC) Message-ID: References: <440e3ca7$0$7322$39cecf19@news.twtelecom.net> <1141823025.751401.183670@j33g2000cwa.googlegroups.com> "Cecil Moore" wrote > Reg Edwards wrote: > > Has it ever occurred to you guys that a coil is a coil wherever it is > > used and always behaves in the same way. > > The coil always behaves in the same way. Unfortunately, the models > used to explain the operation of the coil don't work in the same > way. Please see: > > http://www.ttr.com/corum/index.htm ======================================== Cecil, thanks, I speed-read your extensive pointer. The whole thing could be summarised in one short sentence - "Coils are distributed transmission lines." The same general equations apply to coils of all dimensions, for any number of turns, at all frequencies, in all applications. There's no need to unnecessarily complicate things by artificially dividing them into lumped and other varieties. I had to skip over the bit about Smith Charts. As you are aware I don't know how to use one. It seems Tesla, with HIS coils, knew what it was all about and he couldn't use a Smith Chart either. ---- Reg. Article: 221994 of rec.radio.amateur.antenna From: "Richard Fry" References: <9127-440ED48C-13@storefull-3253.bay.webtv.net> Subject: Re: Bend in xmission line Date: Thu, 9 Mar 2006 05:59:17 -0600 Message-ID: <441017d2_2@newsfeed.slurp.net> "Ian White GM3SEK wrote >I don't have any information on sharp bends, but T-joints > and curved bends with say a foot radius cause no noticeable problems. _______________ UHF broadcast transmit antenna systems often use 90 degree coaxial, mitre-joint elbows carrying upwards of 50 kW with negligible SWR (<1.02:1). RF Article: 221995 of rec.radio.amateur.antenna From: wood@itd.nrl.navy.mil (J. B. Wood) Subject: Re: Military ships fan antenna Date: Thu, 09 Mar 2006 07:44:15 -0500 Message-ID: References: <_1GPf.17539$992.17494@tornado.socal.rr.com> In article , Richard Clark wrote: > On Wed, 08 Mar 2006 19:14:02 GMT, "NA" > wrote: > > >Can anyone tell me about "fan antennas" like those used on the large navy > >ships. > > Hi Jim, > > It is an array of co-planar, parallel monopoles driven at the same, > common point. The size of each in the array is different spanning > from short to long such that at least one is resonant within a wide > band of frequencies. > Hello, and the only fan antenna that I have any experience with is the venerable 2-6 MHz twin fan transmitting antenna used on USN combat ships. This antenna consists of two sets (port, starbaord) of three sloping wires strung from a yardarm on the stack to the feedpoint on the deck. A VSWR of 3 or less is typically achieved using a fixed passive LC network. By design, most of the radiation actually comes from RF currents induced on the stack by the fan wires. Sincerely, John Wood (Code 5550) e-mail: wood@itd.nrl.navy.mil Naval Research Laboratory 4555 Overlook Avenue, SW Washington, DC 20375-5337 Article: 221996 of rec.radio.amateur.antenna From: "Richard Fry" References: <1141757778.043926.115850@i40g2000cwc.googlegroups.com> <1141778806.352135.21840@j52g2000cwj.googlegroups.com> <1141812993.768076.158930@e56g2000cwe.googlegroups.com> <6hNpk4NyLsDEFAnW@ifwtech.co.uk> <7aKdnd_JhqWDjpLZnZ2dnUVZ_smdnZ2d@comcast.com> Subject: Re: Current through coils Date: Thu, 9 Mar 2006 07:09:19 -0600 Message-ID: <44102855_5@newsfeed.slurp.net> "Amos Keag" wrote > My 60 meter mobile antenna is 90 degrees long, 1/4 wavelength resonant at > 18 +j0 ohms [MFJ analyzer]. etc _____________ But how much of that resistance term is the true radiation resistance of your short radiator, and how much is contributed by the coil and "ground plane" losses? Resonating an electrically short radiator with a loading coil doesn't change the radiation resistance of the short vertical antenna (whip) itself -- and the r-f current able to flow in that whip is the source of practically all of the useful radiation that system can produce. The loading coil makes it possible for a practical transmitter to deliver r-f power into that short antenna system, but doesn't change the fact that it is only the short radiator itself that provides the useful radiation. The system may have the net reactance of a resonant, 1/4-wave vertical, but it will still have the radiation resistance of the original, short radiator, and that radiation resistance is the primary determinant of system radiation efficiency when using these coil-loaded antennas. RF Article: 221997 of rec.radio.amateur.antenna From: Roy Lewallen Subject: Re: Vertical vs Horizontal shootout part one Date: Thu, 09 Mar 2006 05:13:06 -0800 Message-ID: <1210af3fma68500@corp.supernews.com> References: <081n025fa3l0tk3ftnb464ga44sia7h7gh@4ax.com> <818s029289valqofpmkpvp2qghuedqrd83@4ax.com> <120ubgbo1kpf523@corp.supernews.com> Reg Edwards wrote: > Danny, > > Since I am not fluent in Latin, could you please tell me what is a > "Factoid"? Danny should be able to translate that. He lives at the coast, where they get lots of touroids from points inland. Roy Lewallen, W7EL Article: 221998 of rec.radio.amateur.antenna From: Roy Lewallen Subject: Re: Current through coils Date: Thu, 09 Mar 2006 05:17:58 -0800 Message-ID: <1210ao82ba5ij56@corp.supernews.com> References: <1141757778.043926.115850@i40g2000cwc.googlegroups.com> <1141778806.352135.21840@j52g2000cwj.googlegroups.com> <1141812993.768076.158930@e56g2000cwe.googlegroups.com> <6hNpk4NyLsDEFAnW@ifwtech.co.uk> Ian White GM3SEK wrote: > . . . > It is true that we agree on a lot of things, but there's only one reason > for that: because physical reality is the same in Oregon, England and > Scotland as it is in Georgia. There is a very high probability that it's > the same in Texas too. No, I really think there's some kind of reality vortex in Texas. Adding to the already overwhelming evidence is the recent news that Tom DeLay overwhelmingly won the primary election so is well on the way to re-election. Reality is quite obviously different there. Roy Lewallen, W7EL Article: 221999 of rec.radio.amateur.antenna From: "Reg Edwards" Subject: Re: Vertical vs Horizontal shootout part one Date: Thu, 9 Mar 2006 13:50:07 +0000 (UTC) Message-ID: References: <081n025fa3l0tk3ftnb464ga44sia7h7gh@4ax.com> <818s029289valqofpmkpvp2qghuedqrd83@4ax.com> <120ubgbo1kpf523@corp.supernews.com> "Dan Richardson adelphia net>" wrote in message news:dj9012dr7outr7koq2701kgmpgg892ijbk@4ax.com... > On Thu, 9 Mar 2006 10:15:23 +0000 (UTC), "Reg Edwards" > wrote: > > >Danny, > > > >Since I am not fluent in Latin, could you please tell me what is a > >"Factoid"? > >---- > >Reg. > > > How about English? Surely your English dictionary has it listed? > > http://encarta.msn.com/dictionary_/factoid.html\\ (definition #1) ========================================= It's not in MY dictionary. I have the Concise Oxford English Dictionary, 1951 edition. But you've got it wrong. "Factoid" doesn't apply to me anyway. ---- Reg. Article: 222000 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Current through coils References: <1141864325.153022.145680@p10g2000cwp.googlegroups.com> <18782-440FBF35-53@storefull-3252.bay.webtv.net> Message-ID: <2rWPf.43827$F_3.22431@newssvr29.news.prodigy.net> Date: Thu, 09 Mar 2006 13:53:02 GMT Richard Harrison wrote: > Suppose the vertical is only 2/3 the height needed for self resonance, > or 60-degrees high. The loading coil must replace about 30-degrees of > missing antenna to bring the vertical to resonance. Here's the reason why. In a standing wave antenna, like a mobile antenna, the forward current and the reflected current are 180 degrees out of phase at the tip of the antenna and their phasor sum is zero. That is one of the laws of reflection physics. Their phasors are rotating in opposite directions so they must each rotate 90 degrees to be in phase and additive at the feedpoint. That's simple geometry. Your above antenna loading coil must contribute ~60 deg to the rotation of the forward and reflected currents. There is nothing else existing in the antenna that can accomplish that absolutely necessary function. > Where is the myth? The lumped circuit model is generating a logical blunder. That model presupposes no phase shift through an inductance. Therefore, there is no phase shift through an inductance. (Circular Logic) Fortunately, the coil ignores our mis-applied man-made model and performs the phase shift anyway. The actual myth is that there is no phase shift through a 75m bugcatcher coil. That myth is rampant on ham radio web pages. The lumped circuit model assumes the proof before a solution to the problem is even attempted. It is a common mistake, known as 'petitio principii', in the solution of logic problems (also known as 'begging the question'). Some folks have simply forgotten that the lumped circuit model presupposes that no reflections exist. It cannot be used in a standing wave antenna environment. Now that these folk have been reminded of the technical facts, it will be interesting to observe the results. Will the erroneous web page information be corrected? -- 73, Cecil http://www.qsl.net/w5dxp Article: 222001 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Current through coils References: <440e3ca7$0$7322$39cecf19@news.twtelecom.net> <1141823025.751401.183670@j33g2000cwa.googlegroups.com> Message-ID: Date: Thu, 09 Mar 2006 13:56:02 GMT Reg Edwards wrote: > I had to skip over the bit about Smith Charts. As you are aware I > don't know how to use one. The basics are really easy. Do you want to learn? -- 73, Cecil http://www.qsl.net/w5dxp Article: 222002 of rec.radio.amateur.antenna From: Michael Coslo Subject: Re: Vertical vs Horizontal shootout part one Date: Thu, 09 Mar 2006 09:17:44 -0500 Message-ID: References: <081n025fa3l0tk3ftnb464ga44sia7h7gh@4ax.com> <818s029289valqofpmkpvp2qghuedqrd83@4ax.com> <120ubgbo1kpf523@corp.supernews.com> Reg Edwards wrote: > "Mike Coslo" wrote >> Reg Edwards wrote: >>> Radiation from feedlines is grossly exaggerated. >> Hi Reg, I can't see who you are replying to - a line of quote would > be >> wunnerful. 8^) > ========================================= > > I'm not replying to anyone in particular. Just to anybody who > discusses power radiated from feedlines. > ========================================= >>> For many purposes, practically it does not occur. >>> >>> When discussing the importance of such radiation one should always >>> crudely estimate its level relative to transmitter or radiated > power. >> Is there any way of doing that? > ========================================== > > Mike, you'd better ask that from people who discuss power radiated > from feedlines. They ought to know! I suspect that the method is to go out and actually try to measure the antenna in question, and perhaps you are being a bit tongue in cheek here? It appears that while there are some general reasons for feedline radiation, the actual situation is so dependent upon the individual antenna setup as to defy any calculation. Assumptions are part of any experiment, and I'm going to go under the assumption that there isn't a *significant* amount of vertical radiation coming from my antenna. Measurement of that could be grist for a later experiment.... - 73 de Mike KB3EIA - Article: 222003 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Current through coils References: <1141864325.153022.145680@p10g2000cwp.googlegroups.com> <18782-440FBF35-53@storefull-3252.bay.webtv.net> <1141907306.333725.215160@i40g2000cwc.googlegroups.com> Message-ID: <4_WPf.52074$Jd.41823@newssvr25.news.prodigy.net> Date: Thu, 09 Mar 2006 14:30:24 GMT w8ji@akorn.net wrote: >>Suppose the vertical is only 2/3 the height needed for self resonance, >>or 60-degrees high. The loading coil must replace about 30-degrees of >>missing antenna to bring the vertical to resonance. > > The myth is in thinking your 60-degree vertical is 90 degree resonant > by virtue of an inductor "replaces about 30-degrees of missing > antenna". I'm sure Richard doesn't believe that since that would be circular logic. It is a law of reflection physics that the forward current and reflected current are equal magnitude and 180 degrees out of phase at the tip of a standing wave antenna. It is a fact of physics that those two currents are back in phase at the feedpoint. Since their phasors are rotating in opposite directions, they both must undergo 90 degrees of rotation between the tip of the antenna and the feedpoint. So what you have to do is explain where 90 degrees of phasor rotation comes from if not partly from the coil. If the coil doesn't rotate the phasors, then the whip must cause that rotation. So, Tom, explain to us how 12 degrees of whip causes 90 degrees of phasor rotation. That explanation should be very interesting. I, and probably Richard H., don't see any other way for the component currents to undergo a 90 degree phase shift. If you do, please enlighten us. > It does not do that. Not in every way, of course. A 30 degree coil certainly doesn't replace the radiating ability of 30 degrees of wire. Is that the point you are trying to make? > Every real-world inductor behave to some extent as a transmission line, > but unless the inductor is spatially large in terms of wavelength or > unless the inductor has a termination impedance significantly higher > than the shunting impedance caused by its own self-capacitance to the > outside world the "transmission line" or radiation mode effects are > negligible. What you don't seem to realize is that a coil can be assumed to be completely lossless, including zero radiation, and essentially the same thing still happens. You obviously do not understand standing waves. Have you ever taken pencil in hand and sketched out the phasor sum of two nearly equal phasors rotating in opposite directions. If you ever did that, you wouldn't keep making that same silly mental blunder over and over. > The ultimate in misunderstanding is when people think the loading > inductor replaces a missing electrical degree length, rather than > understanding a reasonably compact inductor primarily inserts a > reactance that compensates for the capacitive reactance of the antenna > system. Cling to that lumped inductance model for as long as you choose to delude yourself, Tom. It has been proven not to work in a standing wave environment. What is it about, "... one needs transmission line analysis (or Maxwell's equations) to model these electrically distributed structures. Lumped circuit theory fails because it's a theory whose presuppositions are inadequate. Every EE in the world was warned of this in their first sophomore circuits course", that you don't understand? http://www.ttr.com/corum/index.htm > If I have a 10 degree tall base loaded antenna it is a ten degree tall > antenna. It is NOT 90 degree resonant antenna with "80 degrees of > missing length" in the inductor, nor with that 80 degree long inductor > behave like 80 degrees of antenna length would. It is physically 10 degrees tall. The physical height is what determines the radiation pattern. It is electrically 90 degrees long. The electrical length is what determines the feedpoint impedance. Where does that 90 degrees of electrical length come from if not partially from the coil? > The very incorrect concept that an inductor and loaded antenna acts as > a "80 degree coil and ten degree antenna" (substitute the numbers you > want) is what kicked this whole thing off several years ago. Yes, and it is essentially correct. Your mistake in using a lumped circuit model in a standing wave environment has been going on for years. You are not alone in needing to correct your conceptual mistakes. -- 73, Cecil http://www.qsl.net/w5dxp Article: 222004 of rec.radio.amateur.antenna From: richardharrison@webtv.net (Richard Harrison) Subject: Re: Current through coils Date: Thu, 9 Mar 2006 08:37:08 -0600 Message-ID: <18781-44103D94-206@storefull-3252.bay.webtv.net> References: <1141907306.333725.215160@i40g2000cwc.googlegroups.com> Tom, W8JI wrote: "The very incorrect concept that an inductor and loaded antenna acts as an "80 degree coil and 10 degree antenna" (substitute the numbers you want) is what kicked this whole thing off several years ago." I infer the "myth" is that the 80-degree coil might radiate as if it had a physical length of 80-degrees. I had no idea that anyone would conclude that! Radiators in most cases depend upon their physical lengths, which may include the length of an exposed coil, for their radiation characteristics. Glad everyone who responded gave sensible answers. I agree with W7EL too. Best regards, Richard Harrison, KB5WZI Article: 222005 of rec.radio.amateur.antenna From: "Richard Fry" References: <1141864325.153022.145680@p10g2000cwp.googlegroups.com> <18782-440FBF35-53@storefull-3252.bay.webtv.net> <1141907306.333725.215160@i40g2000cwc.googlegroups.com> <4_WPf.52074$Jd.41823@newssvr25.news.prodigy.net> Subject: Re: Current through coils Date: Thu, 9 Mar 2006 08:56:22 -0600 Message-ID: <44104156_2@newsfeed.slurp.net> "Cecil Moore" wrote > It is physically 10 degrees tall. The physical height is what determines > the radiation pattern. It is electrically 90 degrees long. The electrical > length is what determines the feedpoint impedance. Where does that 90 > degrees of electrical length come from if not partially from the coil? ________________ The intrinsic impedance of the radiator consists of its radiation resistance and its reactance. The proper loading coil can provide a net reactance at the feedpoint of the antenna system of ~ zero ohms, but that hasn't changed the radiation resistance of that short radiator. So the coil-loaded, short radiator is not really "electrically" ~90 degrees long -- it just has the reactance of an antenna that is ~90 degrees long. The coil-loaded, short radiator itself still doesn't have the radiation resistance of linear, 1/4-wave antenna. That remains a function of the electrical length of the whip, itself, apart from the effects of the coil. RF From @arrl.net> Newsgroups: rec.radio.amateur.antenna References: <1141864325.153022.145680@p10g2000cwp.googlegroups.com> <18782-440FBF35-53@storefull-3252.bay.webtv.net> <1141907306.333725.215160@i40g2000cwc.googlegroups.com> <4_WPf.52074$Jd.41823@newssvr25.news.prodigy.net> <44104156_2@newsfeed.slurp.net> Subject: Re: Current through coils Lines: 13 X-Priority: 3 X-MSMail-Priority: Normal X-Newsreader: Microsoft Outlook Express 6.00.2800.1409 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1409 Message-ID: NNTP-Posting-Host: 65.69.27.7 X-Complaints-To: abuse@prodigy.net X-Trace: newssvr14.news.prodigy.com 1141917659 ST000 65.69.27.7 (Thu, 09 Mar 2006 10:20:59 EST) NNTP-Posting-Date: Thu, 09 Mar 2006 10:20:59 EST Organization: SBC http://yahoo.sbc.com X-UserInfo1: T[O]STVEMBRSP_@YMZJ\_Q\@TJ_ZTB\MV@BNMRQIMASJETAANVW[AKWZE\]^XQWIGNE_[EBL@^_\^JOCQ^RSNVLGTFTKHTXHHP[NB\_C@\SD@EP_[KCXX__AGDDEKGFNB\ZOKLRNCY_CGG[RHT_UN@C_BSY\G__IJIX_PLSA[CCFAULEY\FL\VLGANTQQ]FN Date: Thu, 09 Mar 2006 15:20:59 GMT Path: news0.isis.unc.edu!news1.isis.unc.edu!arclight.uoregon.edu!hammer.uoregon.edu!news.glorb.com!newscon02.news.prodigy.com!prodigy.net!newsmst01b.news.prodigy.com!prodigy.com!postmaster.news.prodigy.com!newssvr14.news.prodigy.com.POSTED!00eff025!not-for-mail Xref: news0.isis.unc.edu rec.radio.amateur.antenna:222006 "Richard Fry" wrote in message news:44104156_2@newsfeed.slurp.net... > So the coil-loaded, short radiator is not really "electrically" ~90 degrees > long -- it just has the reactance of an antenna that is ~90 degrees long. But Richard, that is what is meant by "electrical" length, that it has the same phase shift as a ~90 degree antenna. -- 73, Cecil, W5DXP Article: 222007 of rec.radio.amateur.antenna From: "Richard Fry" References: <1141864325.153022.145680@p10g2000cwp.googlegroups.com> <18782-440FBF35-53@storefull-3252.bay.webtv.net> <1141907306.333725.215160@i40g2000cwc.googlegroups.com> <4_WPf.52074$Jd.41823@newssvr25.news.prodigy.net> <44104156_2@newsfeed.slurp.net> Subject: Re: Current through coils Date: Thu, 9 Mar 2006 09:42:35 -0600 Message-ID: <44104c28_2@newsfeed.slurp.net> Cecil Moore: >> So the coil-loaded, short radiator is not really "electrically" ~90 >> degrees long -- it just has the reactance of an antenna that is >> ~90 degrees long. (R. Fry quote) > > But Richard, that is what is meant by "electrical" length, that it has > the same phase shift as a ~90 degree antenna. _______________ So the definition of electrical length you use excludes radiation resistance? That resistance is the only parameter giving any antenna the ability produce useful EM radiation in a practical antenna system. And that resistance is a function of the physical properties and configuration of the radiator with respect to the operating frequency. Model a short vertical radiator in NEC, and check its impedance. If short enough, it could be something like 0.1 -j2500 ohms. Now add an inductive reactance to the system to reach resonance. NEC then will show 0.1 +/-0 ohms. Note that the radiation resistance term did not change. That short system is resonant, but it certainly won't have the practical radiation efficiency of a full, 1/4-wave, linear radiator, even though they both have the same "electrical length" by your definition. RF Article: 222008 of rec.radio.amateur.antenna From: "JM" References: <1141922578.317968.87630@u72g2000cwu.googlegroups.com> Subject: Re: Concord,ca Police Department gives people tickets that have 820lbs. in a 1 ton pu truck Message-ID: Date: Thu, 09 Mar 2006 16:55:55 GMT 207.200.116.71 Reported to ISP for breaching T&C. OrgName: Netscape Communications Corp. OrgID: NSCP Address: 501 E. Middlefield City: Mountain View StateProv: CA PostalCode: 94043 Country: US NetRange: 207.200.64.0 - 207.200.127.255 CIDR: 207.200.64.0/18 NetName: NETSCAPE-CIDR NetHandle: NET-207-200-64-0-1 Parent: NET-207-0-0-0-0 NetType: Direct Allocation NameServer: NS.NETSCAPE.COM NameServer: NS2.NETSCAPE.COM Comment: ADDRESSES WITHIN THIS BLOCK ARE NON-PORTABLE RegDate: 1996-09-06 Updated: 2001-03-28 RTechHandle: AOL-NOC-ARIN RTechName: America Online, Inc. RTechPhone: +1-703-265-4670 RTechEmail: domains@aol.net Have a nice day. Article: 222009 of rec.radio.amateur.antenna From: "Cecil Moore" References: <1141864325.153022.145680@p10g2000cwp.googlegroups.com> <18782-440FBF35-53@storefull-3252.bay.webtv.net> <1141907306.333725.215160@i40g2000cwc.googlegroups.com> <4_WPf.52074$Jd.41823@newssvr25.news.prodigy.net> <44104156_2@newsfeed.slurp.net> <44104c28_2@newsfeed.slurp.net> Subject: Re: Current through coils Message-ID: Date: Thu, 09 Mar 2006 17:14:32 GMT "Richard Fry" wrote in message news:44104c28_2@newsfeed.slurp.net... > So the definition of electrical length you use excludes radiation > resistance? Yes, of course a 60 degree coil obviously doesn't radiate like a 60 degree piece of wire. The 60 degrees is merely the phase shift that a traveling wave current undergoes while traveling through the coil. I hope this is not just a semantic problem. When someone says a coil replaces 60 degrees of an antenna, he certainly doesn't mean for radiation purposes (unless he is an absolute dummy). He simply means the coil causes a 60 degree phase shift in the forward current, much like a 60 degree length of wire. And that's all it means. > Model a short vertical radiator in NEC, and check its impedance. If short > enough, it could be something like 0.1 -j2500 ohms. Now add an inductive > reactance to the system to reach resonance. NEC then will show 0.1 +/-0 > ohms. Note that the radiation resistance term did not change. Of course not! Nobody is arguing otherwise. You are obviously confused about what I, and others, are saying. > That short system is resonant, but it certainly won't have the practical > radiation efficiency of a full, 1/4-wave, linear radiator, even though they > both have the same "electrical length" by your definition. Is this a straw man? Nobody has said anything remotely resembling any argument otherwise. Electrical length doesn't have much to do with radiation. The radiation resistance and therefore efficiency, is closely associated with the physical length. Electrical length mainly has to do with phasor rotation. If a traveling wave current phasor rotates 90 degrees while flowing through a coil, the coil's electrical length is 90 degrees. That's a pretty simple concept. The coil can even be considered to be lossless and non- radiating in some relatively efficient antenna systems without introducing much of an error. -- 73, Cecil, W5DXP Article: 222010 of rec.radio.amateur.antenna From: "Cecil Moore" References: <1141864325.153022.145680@p10g2000cwp.googlegroups.com> <18782-440FBF35-53@storefull-3252.bay.webtv.net> <1141907306.333725.215160@i40g2000cwc.googlegroups.com> <4nh012l7ogdc07e4vcciuj0l21usbbtpnp@4ax.com> Subject: Re: Current through coils Message-ID: Date: Thu, 09 Mar 2006 17:51:48 GMT "Wes Stewart" wrote > if you go here: > > http://www.k6mhe.com/n7ws > > and look at either Note 1 or 2 and then look at figures 1 and 2 this > might change your mind about the current distribution. Nobody is disputing the current rise through a coil. In fact, I have been pointing it out. The coil does distort the current away from the nice cosine envelope of a 1/2WL thin wire dipole. Your graphs show standing wave current which doesn't flow. (Its phase angle doesn't rotate.) Therefore, the magnitude of the standing wave current can be any value depending upon where it is located in the system. Wes, please take a look at http://www.qsl.net/qrzgif35.gif to find out why standing wave current can have any value and is thus unimportant. EZNEC plots the current in much the same way that you have. So are the EZNEC results wrong and yours right? The fact is that a standing wave current plot is close to meaningless. Why are we continuing to discuss standing wave current? What we need to plot is the forward traveling wave current and the reflected traveling wave current which are the two components of your standing wave current graphs. Do you have any simulation software that will plot the forward current and reflected current? Nobody is going to understand what is really happening until we get a plot of those two component waves or at least an estimated graph of the underlying superposed currents. In fact, how about your best estimate of a graph of forward and reflected currents through the coil including phase shifts? Only then are you likely to understand what we are talking about.. -- 73, Cecil, W5DXP Article: 222011 of rec.radio.amateur.antenna From: Roy Lewallen Subject: Re: Current through coils Date: Thu, 09 Mar 2006 10:20:08 -0800 Message-ID: <1210ser332cpg35@corp.supernews.com> References: <1141864325.153022.145680@p10g2000cwp.googlegroups.com> <18782-440FBF35-53@storefull-3252.bay.webtv.net> <1141907306.333725.215160@i40g2000cwc.googlegroups.com> David Shrader wrote: > w8ji@akorn.net wrote: > > SNIPPED > >> > >> If I have a 10 degree tall base loaded antenna it is a ten degree tall >> antenna. It is NOT 90 degree resonant antenna with "80 degrees of >> missing length" in the inductor, nor with that 80 degree long inductor >> behave like 80 degrees of antenna length would. >> > > I beg to differ. > > If I have a 15 degree long physical antenna, center loaded at 10 > degrees, with 5 degrees above the coil I do have a 15 degree physical > antenna. That does not mean the antenna is NOT 90 degrees elctrically > long! Resonance requires that the reactive components cancel both in > amplitude and phase! Each reactive component introduces phase shift into > the system. The antenna, without a loading coil, is composed of three > terms: resistance [radiation and loss], self capacitance, and self > inductance. In a shortened antenna the self capacitance dominates and > the resultant phase shift is NOT zero. It is required to add inductance > to achieve resonance [phase shift = 0]. If an antenna is electrically 15 > degrees long and the self inducance does not reduce the reactive phase > shift to zero PHASE SHIFT MUST BE ADDED TO THE ANTENNA for resonance. > This phase shift is accomplished by the loading coil. > > Now, when that antenna is fed with 1 ampere [Imax] at the base of the > antenna and the feed current follows a cosine distribution to the base > of the coil [I = Imax*cos(theta)][theta=10], you claim that the current > exiting the coil is also Imax*cos(theta), or 98.5% of max value. > > However, if we start with zero current at the tip, a valid initial > condition, and let current increase by a sine function then I = > Imax*sin(theta1][theta1 = 5 degrees] The result is simply 9% of max > value. There seems to be a disconnect here. 98.5% = 9% ????????? > > If you claim Imax @ 98.5% exits the coil and has a value of 96.6% [I2] > at the tip then boundary conditions require total reflection. That > requires a 180 degree phase reversal at the I2 amplitude to satisfy the > boundary condition. Now the reflected current into the top of the coil > is -I3 = 99.6% of -I2. The reflected current exiting the bottom of the > coil is, by your reasoning -I3. The reflected current at the base is > 96.6% of -I2, or 93% of Imax. > > If I understand you correctly, then the measured value at the base of > the 15 degree antenna is NOT 1 ampere but only 0.07 amperes. > > Obviously, the coil is acting as something more than a simple L. It is > adding and inductive phase shift. The vertical has capacitance to the > local ground. The vertical also has a self inductance!! That self > inducatance is insufficient to complete the 90 phase shift required for > resonance. Therefore, I offer that the loading coil provides the > required additional inductance for resonance. You can replace the antenna with a box containing a series resistor and capacitor, and except for the field there's no steady state way to tell it from an antenna. A physically small inductor such as a toroid will function exactly the same in both cases. (I limited it to being physically small, since a larger inductor will interact with the antenna's field.) So your explanation should work just as well when the inductor is in series with a simple RC as when it's in series with an antenna. I can easily write the equations describing the voltage and current at every part of the resulting RLC circuit, using circuit analysis techniques which have been around for over a century. You're saying either that they're wrong, or that you can tell by looking at the terminals of a black box whether it contains an antenna or a simple RC. Can you describe the method you'd use, restricting yourself to steady state measurements, how you'd tell the difference? Roy Lewallen, W7EL Article: 222012 of rec.radio.amateur.antenna From: Butch Magee Subject: Re: OT for Cecil or any other ex RRAPers Date: Thu, 09 Mar 2006 12:33:45 -0600 Message-ID: <1210t89q0dl50b5@corp.supernews.com> References: <1141756042.224852.90540@j52g2000cwj.googlegroups.com> <1141837212.960395.167340@j52g2000cwj.googlegroups.com> Cecil Moore wrote: > an_old_friend wrote: > >> well thanks for responding if you ha[en to remmber (after all I might >> have just started your memory moving) > > > :-) My memory moved out a few years ago. :-) Memory does move out on us, mine did years ago. You still have a hog though Cecil, my wife won't let me have one! Butch Article: 222013 of rec.radio.amateur.antenna From: "Cecil Moore" References: <1141864325.153022.145680@p10g2000cwp.googlegroups.com> <18782-440FBF35-53@storefull-3252.bay.webtv.net> Subject: Re: Current through coils Message-ID: Date: Thu, 09 Mar 2006 18:41:43 GMT "Wes Stewart" wrote : > Maybe part of the myth is that the antenna must be resonant to work. > Nothing could be further from the truth. Can we agree that if the feedpoint impedance is purely resistive, then the antenna is resonant? > How about this thought experiment: Assume a too short for resonance > monopole, that has its feedpoint impedance made non-reactive by the > insertion of a "base loading coil." All kinds of arguments, including > this one, arise about what the role of the coil is, what its current > distribution is, how it affects efficiency and so forth. > > To minimize these arguments, let's stop calling the inductor a "base > loading coil" and call it part of an "L-network feedpoint matching > network." Now the radiator isn't resonant and the resulting feedpoint > reactance (and resistance) is matched separately with the external > network. > > Has the radiator current distribution changed? No. Does the inductor > in the L-network "make up" some number of electrical degrees in the > radiator? Not from my viewpoint. This can be easily addressed by looking at a G5RV on 40m. On 40m, the feedpoint impedance at the dipole is about 500+j100 ohms. The parallel twinlead matching section is about 110 degrees long. The resonant impedance looking into the matching section is about 27+j0 ohms. So the G5RV matching section has indeed made up about 110 degrees needed by the antenna *system*. The tuned matching section has increased the electrical length of the antenna *system* by 110 degrees so its a pretty good match for coax.. The same goes for an antenna loading coil no matter where it is located. If the short whip antenna system needs 60 degrees to be matched (resonated) the coil provides 60 degrees of phase shift. That's all we are saying when we say the coil replaces 60 of degrees of an antenna system. And the basic argument is whether a lumped circuit analysis can be used on a coil when reflections are present. The answer is NO! If an antenna system needs 60 degrees to be resonant, it can be done in any number of ways. You can give it 60 degrees of transmission line or you can give it 60 degrees of coil. But please note that the 60 degrees of phase shift in the loading coil has no effect on the phase of the standing wave current. The phase of the standing wave current essentially doesn't change all up and down a 1/2WL dipole. Why would you expect it to change in a shortened monopole. The fact that it doesn't changing is essentially meaningless. It doesn't change whether a coil is present or not. -- 73, Cecil, W5DXP Article: 222014 of rec.radio.amateur.antenna From: Roy Lewallen Subject: Re: Current through coils Date: Thu, 09 Mar 2006 11:09:23 -0800 Message-ID: <1210vb5rp7eguad@corp.supernews.com> References: <1141864325.153022.145680@p10g2000cwp.googlegroups.com> <18782-440FBF35-53@storefull-3252.bay.webtv.net> <1141907306.333725.215160@i40g2000cwc.googlegroups.com> For what it's worth -- I've avoided this discussion for two primary reasons. One is that it saddens me to see this "controversial" topic being brought up yet again after having been discussed at great length a number of times before. There's no reason I can see for it other than Cecil's religious zeal and dogged determination. The second reason is that I hate to be reminded how easily some people can be manipulated to wholly ignore well known physics and embrace alternate theories which are devoid of the ability to produce predictions or numerical results to demonstrate their validity. We live with it every day in our ordinary lives, seeing the astrology column in the newspaper (and learning that it's been a driving force behind top level government decisions), homeopathic remedies at the drug store, and so forth. It's hard to see it keep surfacing here also. Fortunately, some very good, honest, and knowledgeable people have been doing a very good job of presenting the facts. These include Tom, W8JI; Ian, G3SEK; Wes Stewart, N7WS; and Gene Fuller, W4SZ. Anyone who is truly interested in understanding the topic (which is fundamentally very simple) would do well to read what those folks have written and are writing. Because they're dealing with facts and well known phenomena, they can back up what they say with numbers and the ability to explain the phenomena you see. I'd like to add one note to particularly pay attention to Ian's postings on March 6 and 8 explaining the difference between an inductor and inductance. When I and others have spoken of a "physically small coil" we're talking about something resembling a pure inductance. As Ian and others have said, the first step in understanding this topic is to understand how the idealized component works. Only after that can you add the effects of coupling to external fields, which explain the current difference you typically do see between the ends of a real inductor loading an antenna. The red herring in this discussion is the attempt to attribute this effect to something fundamental about inductances, rather than the effect of external fields interacting with a real inductor of significant physical size. Part of this is understandable, because an inductor can be surprisingly small and still exhibit substantial current difference from one end to the other when in the field of a short antenna, because the field from the antenna is very intense. The field from the inductor is also quite large, making noticeable capacitive coupling nearly always present, which also provides a path for displacement current. So it's somewhat natural to assume that the current difference between ends is more fundamental than it really is. But the argument has been taken well beyond reason by the zeal to explain every phenomenon by means of reflecting waves and packets of average power. It's not necessary at all, and all that does is to provide a confounding factor to obscure the simplicity of what's really happening. Since the basis for this approach is largely contrived and devoid of the ability to produce quantitative results, it's easy to make pronouncements which can't be verified. It's pretty obvious that objects in motion come to rest naturally without any external force. You reach this conclusion by failing to separate the external force of friction from the inherent inertia of the object. The problem here is exactly the same -- people are failing to separate the phenomenon of external coupling from the inherent properties of inductance, and concluding that observed current differences between the ends of loading inductors are caused by some inherent property of inductance. I can imagine people arguing about the basic property of objects to spontaneously come to rest long after Newton proved it otherwise. Actually, I wouldn't even be surprised if there's some Newtonian Cecil who's still arguing about it. Roy Lewallen, W7EL Article: 222015 of rec.radio.amateur.antenna From: "Cecil Moore" References: <1141864325.153022.145680@p10g2000cwp.googlegroups.com> <18782-440FBF35-53@storefull-3252.bay.webtv.net> <1141907306.333725.215160@i40g2000cwc.googlegroups.com> <1210ser332cpg35@corp.supernews.com> Subject: Re: Current through coils Message-ID: Date: Thu, 09 Mar 2006 19:12:30 GMT "Roy Lewallen" wrote: >A physically small inductor such as a toroid will > function exactly the same in both cases. (I limited it to being > physically small, since a larger inductor will interact with the > antenna's field.) You're missing the point, Roy. It indeed does function the same way in both cases but if there are reflections present, your lumped circuit analysis rules are known to fail.Your analysis of both cases may be equally wrong in both cases. What is the traveling wave current delay through the coil in degrees? That's easy to measure. That current delay is the degrees that the coil supplies to the antenna. You can ignore any measurements involving standing wave current as being essentially meaningless. What is important is the traveling- wave current delay through the coil. Please measure it and report what it is for your 'physically small toroid'. Your lumped circuit analysis pre-assumes a zero delay through the coil. That delay is certainly not zero in the real world. -- 73, Cecil, W5DXP Article: 222016 of rec.radio.amateur.antenna From: richardharrison@webtv.net (Richard Harrison) Subject: Re: Bend in xmission line Date: Thu, 9 Mar 2006 13:11:25 -0600 Message-ID: <24187-44107DDD-279@storefull-3251.bay.webtv.net> References: Ian, GM3SEK wrote: "Can you describe that please?" Gladly. For low loss at 100 KW, you use large cable and wide spacings at 600 ohms. It may have been more economical to use more conductors but for simplicity we stuck with a 2-wire balanced feed system. We had at that particular time and location the largest congregation of high-powered shortwave transmitters and directional antennas in the world. We installed a crossbar switching system so that almost any transmitter could access any antenna. We were on the air with most transmitters operating nearly 24 hours a day, but switching antennas several times a day according to our announced program schedule to accommodate anticipated propagations to the target areas served. Ed Laport as Chief Engineer of RCA International had as much experience as anyone with commercial shortwave radio, so we relied upon him for information and weren`t disappointed. On page 396 of "Radio Antenna Engineering", Ed illustrates a corner made using two transmission lines. He shows a single pole with two crossarms, one above the other and making the horizontal angle required for the intersection. He terminates the lines one on each crossarm. Jumpers are used to interconnect the two lines. Our line cables were akin to welding cable. We joined them with sleeves and fittings attached with a hydraulic press (Nicropress). With wide spacing the lines are tolerant of bumps and don`t tend to flashover. Ed gives a graph of the value of the ratio of line spacing to cable radius versus Zo. For 600 ohms the ratio is about 150. Best regards, Richard Harrison, KB5WZI Article: 222017 of rec.radio.amateur.antenna From: "Cecil Moore" References: <1141864325.153022.145680@p10g2000cwp.googlegroups.com> <18782-440FBF35-53@storefull-3252.bay.webtv.net> <1141929188.910581.171220@p10g2000cwp.googlegroups.com> Subject: Re: Current through coils Message-ID: Date: Thu, 09 Mar 2006 20:21:42 GMT wrote: > 1.) Cecil wants everyone to start using reflection wave models to > analyze every antenna system in the world. No, I simply want you and others to stop using a known invalid model for every standing wave antenna system in the world. This is a quote from the first web page below: The capital letters are where the author used bold italics for emphasis. "... - no wave interferrence and no standing waves can be present on lumped elements. The problem has been that many experimenters working with self-resonant helices have PURSUED THE CONCEPT OF COIL SELF- CAPACITANCE WITHOUT REALLY UNDERSTANDING WHERE THE NOTION COMES FROM OR WHY IT WAS EVER INVOKED BY ENGINEERS. For that, they will have to go read R.W.P. King's wonderful old book, "Electromagnetic Engineering, McGraw-Hill, 1945. ... On page 465, the Harvard Professor points out that, for coils whose *wire length* exceeds 1/6 wavelength, ...'an adequate representation of the reactance of a coil with a nonuniformly distributed currentr is NOT POSSIBLE in terms of a coil with a uniform current [a lumped element inductance] ...' Period. Resonant FIELDS present surprises to engineers with limited training." Certainly sounds like he is talking about you, Tom. "Electronic Engineering" was written before you were born. Why are you ignorant of the technical facts presented in it? http://www.ttr.com/corum/index.htm http://www.ttr.com/TELSIKS2001-MASTER-1.pdf The .pdf paper is a pier-reviewed publication by the IEEE. Here's what it says about the model you have chosen to use. "Of course, the uniform current assumption has no validity for coils operating anywhere near self-resonance!" "The failure of any limped element circuit model to describe the real world lies at its core inherent *presupposition*: the speed of light is presumed to be infinite in the wave equation. ... Consequently, lumped element circuit theory does not (and cannot) accurately embody a world of second order partial differential equations in space and time." "The concept of coil "self-capacitance" is an attempt to circumvent transmission line effects on small coils when the current distribution begins to depart from its DC behavior." "There are a great number of formulae for coil self-capacitance. None are of particular value for quarter-wave helical resonators anywhere near the 90 degree point." "The delusion is that the short coil is then made to operate in the lumped element regime ...". That you refuse to give up on an invalid method in the face of overwhelming evidence is amazing. > What he wants me or others to do is a moot point. Afraid of what you will find? The first web page above says: "Lumped circuit theory isn't absolute truth, it's only an analytical theory - and in these resonators we have the case where this sophmore theory fails experimentally." Do the experiment, Tom, and discover exactly how sophmorish you are being. > I am concerned about the commonly held but very incorrect view that > current travels through an inductor turn-by-turn, and that a loading > inductor somehow shifts the phase of and/or level of current to "make > up for missing degrees". Tom, that's what any matching network does. Loading coils are no exception. > My only concern is people not understanding how an inductor and short > antenna actually behaves. I am concerned about you not understanding, Tom. Don't you believe the information posted on those web pages above. Don't you think a peer-reviewed IEEE publication that disagrees with you is worth a second thought from you. Don't you think ignoring the knowledge published by experts in the field is a little naive? -- 73, Cecil, W5DXP Article: 222018 of rec.radio.amateur.antenna From: ISRAEL FAGBEMI Subject: BECOME A DOT.COM MILLIONAIRE WITH ONLY $5.99Cents or $1K. Message-ID: Date: Thu, 9 Mar 2006 15:50:19 -0500 Article: 222019 of rec.radio.amateur.antenna From: "Cecil Moore" References: <1141864325.153022.145680@p10g2000cwp.googlegroups.com> <18782-440FBF35-53@storefull-3252.bay.webtv.net> <1141907306.333725.215160@i40g2000cwc.googlegroups.com> <1210vb5rp7eguad@corp.supernews.com> Subject: Re: Current through coils Message-ID: Date: Thu, 09 Mar 2006 21:01:13 GMT "Roy Lewallen" wrote: >> I've avoided this discussion for two primary reasons. One is that it > saddens me to see this "controversial" topic being brought up yet again > after having been discussed at great length a number of times before. > There's no reason I can see for it other than Cecil's religious zeal and > dogged determination. The reason is that you are wrong and I have provided expert testimony that you are wrong. I'm trying to stop you from speading false information so don't fault me for that. The fact that you refuse to have a technical discussion with me in spite of the numerous expert postings that prove you are using an invalid model, speaks volumes. The results of the spreading of lumped-circuit analysis myths is that you are hoodwinking the uninitiated. > Fortunately, some very good, honest, and knowledgeable people have been > doing a very good job of presenting the facts. These include Tom, W8JI; > Ian, G3SEK; Wes Stewart, N7WS; and Gene Fuller, W4SZ. This is an argumentum ad verecundiam, a well known logical diversion and not a technical argument. I have quoted just as many experts and you have ignored them. In particular, R.W.P. King is quoted from "Electromagnetic Engineering": ... for coils whose *wire length* exceeds 1/6 wavelength, an adequate representation of the reactance of a coil is *NOT POSSIBLE* in terms of a coil with a uniform current [a lumped-element inductance]..." Roy, my 75m bugcatcher coil, made from 44 feet of wire, is more than 1/6 wavelength of wire. R.W.P. King says your lumped-circuit analysis is *NOT POSSIBLE*. He used bold print and underlined the words, *NOT POSSIBLE*. Ignoring the quotations from the true experts is just going to leave you ignorantly spreading old wives' tales. Is that really how you want to be remembered here? Why are all of you alleged "experts" unwilling to discuss technical quotes like R.W.P. King's above? Are you afraid that readers will discover your common mistake which Dr. Corum calls "sophomoric"? As Dr. Corum says: "There are no standing waves on a lumped element circuit component. (In fact, lumped-element circuit theory inherently employs the cosmological presupposition that the speed of light is infinite, as every EE sophomore should know." Why do you choose to absolutely ignore that technical knowledge? -- 73, Cecil, W5DXP Article: 222020 of rec.radio.amateur.antenna From: "Reg Edwards" Subject: Re: Current through coils Date: Thu, 9 Mar 2006 21:29:11 +0000 (UTC) Message-ID: References: <1141864325.153022.145680@p10g2000cwp.googlegroups.com> <18782-440FBF35-53@storefull-3252.bay.webtv.net> <1141907306.333725.215160@i40g2000cwc.googlegroups.com> <4_WPf.52074$Jd.41823@newssvr25.news.prodigy.net> <44104156_2@newsfeed.slurp.net> <44104c28_2@newsfeed.slurp.net> Summary of design of a short loaded vertical antenna. There is a 90-degree phase shift between the feedpoint and the tip of the antenna. With a short antenna most of the 90 degree phase shift is due to the loading coil which is, in effect, a transmission line. The transmission line has Zo, velocity, phase-shift and some attenuation due to radiation resistance plus wire loss resistance. Radiation resistance and phase-shift are directly proportion to coil length, as are L and C and wire resistance. Q = Omega*Total Inductance / Total R as is usual. Bandwidth = Resonant Freq / Q. Radiating efficiency takes into account wire resistance below the coil, coil resistance, resistance of the wire above the coil, plus ground loss resistance, plus the sum of the three radiation resistances. All resistances are referred to the antenna feedpoint. With short coils, radiation resistance of the coil is usually much less than that due to the length of the wires above and below it. With a helical antenna, wire loss resistance is always greater than its radiation resistance. At low HF, with a good set of ground radials, the loss resistance of coil wire usually predominates. At high HF, the ground loss usually predominates but the radiation resistance becomes important. The whole business is calculable. There are few rules of thumb. The only thing which is missing is the radiation pattern. If you don't already know what the radiation pattern is in the vertical plane then Eznec will attend to that. Actually, in the vertical plane, radiation is approximately proportional to the cosine of the elevation angle. The horizontal groundwave is stongest. Some of the parameters need not be explicitly calculated. EXAMPLE: Starting data: Height of antenna below coil = 2 metres = 79 inches. Diameter of antenna below coil = 25mm = 1 inch. Length of antenna above coil = 1 metre = 39 inches. Diameter of antenna above coil = 10mm = 0.4 inches. Length of coil = 152mm = 6 inches. Diameter of coil = 76mm = 3 inches. Overall antenna height = 3.152 metres = 124 inches = 10.3 feet. Ground electrode loss resistance = 5 ohms. Frequency = 3.8 MHz. Calculated data: Number of turns on coil = 53 Wire gauge = 13 or 14 awg. Radiating efficiency = 10 percent. Loss relative to full-size 1/4-wave vertical = 9.4 dB. Self-resonant frequency of the coil = 8.2 MHz. For maximum efficiency the coil is located at 50% of the overall antenna height. But there's not much extra loss by using base loading. For other calculated data use program LOADCOIL which is about 6 years old and I think I have lost the source code. ---- ........................................................... Regards from Reg, G4FGQ For Free Radio Design Software go to http://www.btinternet.com/~g4fgq.regp ........................................................... Article: 222021 of rec.radio.amateur.antenna From: richardharrison@webtv.net (Richard Harrison) Subject: Re: Current through coils Date: Thu, 9 Mar 2006 15:21:37 -0600 Message-ID: <23728-44109C61-216@storefull-3254.bay.webtv.net> References: <1141936980.983089.217740@v46g2000cwv.googlegroups.com> Roy, W7EL wrote: "It`s pretty obvious that objects in motion come to rest naturally without any external force." I`d want to switch topics from coils to inertia and Newton had I insisted a coil must have the same current at both ends in an r-f environment. Like squid they try to get away in a flood of ink. Best regards, Richard Harrison, KB5WZI Article: 222022 of rec.radio.amateur.antenna From: "Cecil Moore" References: <1141864325.153022.145680@p10g2000cwp.googlegroups.com> <18782-440FBF35-53@storefull-3252.bay.webtv.net> <1141907306.333725.215160@i40g2000cwc.googlegroups.com> <1210ser332cpg35@corp.supernews.com> <1141936980.983089.217740@v46g2000cwv.googlegroups.com> Subject: Re: Current through coils Message-ID: Date: Thu, 09 Mar 2006 21:40:40 GMT wrote in message news:1141936980.983089.217740@v46g2000cwv.googlegroups.com... > > Cecil Moore wrote: > > > What is the traveling wave current delay through the coil in > > degrees? That's easy to measure. That current delay is the > > degrees that the coil supplies to the antenna. You can ignore > > any measurements involving standing wave current as being > > essentially meaningless. What is important is the traveling- > > wave current delay through the coil. Please measure it and > > report what it is for your 'physically small toroid'. > > > > Your lumped circuit analysis pre-assumes a zero delay > > through the coil. That delay is certainly not zero in the real > > world. > > The problem with people doing work to verify this is even if several > people measure something, Cecil will ignore results. I will accept what you find as long as long as the method to obtain the results is valid.. Roy's earlier measurements are virtually meaningless since he was measuring standing wave current which doesn't even flow (phase is constant and fixed around zero degrees). You guys always seem to make measurements that support your preconceived notions and avoid measurements that don't But you have already started what I am asking, Tom. You measured a voltage phase shift of 60 degrees through a 100uH coil at 1 MHz. The current is known to lag the voltage through a coil so the current phase delay is more than 60 degrees. I wouldn't be surprised to see it at 120+ degree lag in the current. So your own experiment proves you are wrong. How do you get away with such behavior without anyone noticing?. (Hint: there are a handful of knowledgeable lurkers who have noticed.) When you measured S12, was the load side of the coil looking into 50 ohms? In the web pages I previously posted, R.W.P. King, in "Electromagnetic Engineering", asserts that you cannot use a lumped circuit analysis on a coil containing 1/6 wavelength of wire. Your 100uH coil above exhibits 60 degrees of phase shift even for the voltage and that's 1/6 wavelength for voltage - even more for current. The lumped-circuit model assumes that the voltage is traveling at an infinite speed, faster than light. Since you believe so strongly in the lumped-circuit model, wonder why your measurement didn't reflect that fact? :-) -- 73, Cecil, W5DXP Article: 222023 of rec.radio.amateur.antenna From: "Cecil Moore" References: <1141936980.983089.217740@v46g2000cwv.googlegroups.com> <23728-44109C61-216@storefull-3254.bay.webtv.net> Subject: Re: Current through coils Message-ID: Date: Thu, 09 Mar 2006 21:53:55 GMT "Richard Harrison" wrote: > I`d want to switch topics from coils to inertia and Newton had I > insisted a coil must have the same current at both ends in an r-f > environment. Richard, lest you get nit-picked to death again, let's be clear that you are talking about a standing-wave r-f environment. If a coil is installed in a traveling-wave r-f environment, with no standing waves, the magnitude of the current through the coil will be the same at both ends, minus losses. It's the phasor sum of the forward and reflected current phasors that causes such a large variation in coil current in a standing- wave r-f environment illustrated by the graphic at: http://www.qsl.net/w5dxp/qrzgif35.gif Wonder why none of those resident gurus have bothered to explain the current distribution in that coil? Have you noticed my questions about the technical references that I have provided just keeps piling up with no responses? -- 73, Cecil, W5DXP Article: 222024 of rec.radio.amateur.antenna From: "Cecil Moore" References: <1141864325.153022.145680@p10g2000cwp.googlegroups.com> <18782-440FBF35-53@storefull-3252.bay.webtv.net> <1141907306.333725.215160@i40g2000cwc.googlegroups.com> <1210ser332cpg35@corp.supernews.com> <1141936980.983089.217740@v46g2000cwv.googlegroups.com> <1141941856.152044.56800@u72g2000cwu.googlegroups.com> Subject: Re: Current through coils Message-ID: Date: Thu, 09 Mar 2006 22:38:28 GMT wrote in message news:1141941856.152044.56800@u72g2000cwu.googlegroups.com... > Cecil Moore wrote: > > I will accept what you find as long as long as the method to > > obtain the results is valid.. Roy's earlier measurements are > > virtually meaningless since he was measuring standing wave > > current which doesn't even flow (phase is constant and > > fixed around zero degrees). > > Shame on you for measuring current that doesn't flow through a current > transformer. Standing wave net current doesn't flow back and forth along the wire. That's why they call it a *standing* wave. Why don't you know that already? At any point on the wire, the H-fields and E-fields are exchanging energy at the frequency of operation. That's certainly enough reason for an inductive pickup to respond. Why is that a surprise to you or Roy? Because you two mistakenly thought net standing wave current flows and ignorantly measured it? All you measured was the orthogonal exchange of energy between the two fields. Nothing was moving except the underlying forward and reflected currents. Isn't this stuff taught anymore? What have you guys done - gotten together and elected yourselves into a club of omniscient gurus? Please take a look at the laws of reflection physics. It appears that you are ignorant of most of them. -- 73, Cecil, W5DXP Article: 222025 of rec.radio.amateur.antenna From: Roy Lewallen Subject: Re: Current through coils Date: Thu, 09 Mar 2006 15:28:42 -0800 Message-ID: <1211ehep8b9i647@corp.supernews.com> References: <1141864325.153022.145680@p10g2000cwp.googlegroups.com> <18782-440FBF35-53@storefull-3252.bay.webtv.net> <1141907306.333725.215160@i40g2000cwc.googlegroups.com> <1210ser332cpg35@corp.supernews.com> <1141936980.983089.217740@v46g2000cwv.googlegroups.com> w8ji@akorn.net wrote: > Cecil Moore wrote: > >> What is the traveling wave current delay through the coil in >> degrees? That's easy to measure. That current delay is the >> degrees that the coil supplies to the antenna. You can ignore >> any measurements involving standing wave current as being >> essentially meaningless. What is important is the traveling- >> wave current delay through the coil. Please measure it and >> report what it is for your 'physically small toroid'. >> >> Your lumped circuit analysis pre-assumes a zero delay >> through the coil. That delay is certainly not zero in the real >> world. > > The problem with people doing work to verify this is even if several > people measure something, Cecil will ignore results. > > 73 Tom Indeed. Or alter his interpretation to fit the data. Anyone interested in seeing the results of careful measurements should see the "Current in antenna loading coils controversy (long)" in November 2003, where I made and reported just such measurements. Pay careful attention to Cecil's various predictions of what the results would be using his method of explanation. Roy Lewallen, W7EL Article: 222026 of rec.radio.amateur.antenna From: Gene Fuller Subject: Re: Current through coils References: <1141864325.153022.145680@p10g2000cwp.googlegroups.com> <18782-440FBF35-53@storefull-3252.bay.webtv.net> <1141929188.910581.171220@p10g2000cwp.googlegroups.com> Message-ID: Date: Thu, 09 Mar 2006 23:40:05 GMT Cecil, A few random comments: * I have done a number of "peer reviews" for IEEE and AIP publications as well as other publications. I have seen comments from the other reviewers. In general peer review is better than nothing, but in many cases it doesn't mean diddly. * The Tesla coil crowd seems to contain an unusually large fringe. I know nothing of the authors of your latest bible, but in any case I was not particularly impressed with their credentials or their paper. I love the part, "Lumped circuit theory isn't absolute truth, it's only an analytical theory about lumped models". As if their work is somehow absolute truth. (Back to the previous bullet: I have never seen any serious peer-reviewed paper that would contain such a statement.) * No one is his right mind would think that a Tesla coil with a gazillion closely spaced turns is equivalent to a bugcatcher coil. No one should think that an axial mode helical antenna is equivalent to an ordinary loading coil either. * You are waaaay too hung up on the subject of standing waves vs. traveling waves. You may have noticed that the standard treatments of antennas in texts and other references barely mention the terms. They merely discuss the actual current in the antenna. The fundamentally important entity in radiation is accelerated charge, just as Tom noted. At any point in an antenna, such as the loaded monopole discussed here, there is simply a current, not a traveling wave or a standing wave. If you could examine the antenna microscopically at a single point you would find electrons sloshing back and forth. You could not tell if the current was represented by a standing wave or a traveling wave. The standing wave description relates to the overall amplitude characteristic of the current when you look at the entire antenna. This amplitude characteristic is certainly important in calculation of details of the radiation field, but it does not change the fundamental property of radiation or the physical processes ongoing in the antenna. It is just plain silly to argue that a standing wave is totally inert and does not flow back and forth. * Distributed or network models are mathematically convenient for treating complex problems. However, they add precisely zero new information to the underlying physical reality described by Maxwell's equations. They offer no new physics beyond lumped models. They can be misapplied just the same as lumped models can be misapplied. It is generally best to drive a nail with a hammer, but a monkey wrench will also do the job. It is best to choose the most efficient tool, but that does not mean others won't work. 73, Gene W4SZ Cecil Moore wrote: > wrote: > >>1.) Cecil wants everyone to start using reflection wave models to >>analyze every antenna system in the world. > > > No, I simply want you and others to stop using a known invalid > model for every standing wave antenna system in the world. > This is a quote from the first web page below: The capital > letters are where the author used bold italics for emphasis. > > "... - no wave interferrence and no standing waves can be > present on lumped elements. The problem has been that many > experimenters working with self-resonant helices have > PURSUED THE CONCEPT OF COIL SELF- > CAPACITANCE WITHOUT REALLY UNDERSTANDING > WHERE THE NOTION COMES FROM OR WHY IT WAS > EVER INVOKED BY ENGINEERS. For that, they will have > to go read R.W.P. King's wonderful old book, "Electromagnetic > Engineering, McGraw-Hill, 1945. ... On page 465, the Harvard > Professor points out that, for coils whose *wire length* exceeds > 1/6 wavelength, ...'an adequate representation of the reactance > of a coil with a nonuniformly distributed currentr is NOT > POSSIBLE in terms of a coil with a uniform current [a lumped > element inductance] ...' Period. Resonant FIELDS present > surprises to engineers with limited training." > > Certainly sounds like he is talking about you, Tom. "Electronic > Engineering" was written before you were born. Why are you > ignorant of the technical facts presented in it? > > http://www.ttr.com/corum/index.htm > > http://www.ttr.com/TELSIKS2001-MASTER-1.pdf > > The .pdf paper is a pier-reviewed publication by the IEEE. Here's > what it says about the model you have chosen to use. > > "Of course, the uniform current assumption has no validity for coils > operating anywhere near self-resonance!" > > "The failure of any limped element circuit model to describe the > real world lies at its core inherent *presupposition*: the speed of > light is presumed to be infinite in the wave equation. ... Consequently, > lumped element circuit theory does not (and cannot) accurately > embody a world of second order partial differential equations in > space and time." > > "The concept of coil "self-capacitance" is an attempt to circumvent > transmission line effects on small coils when the current distribution > begins to depart from its DC behavior." > > "There are a great number of formulae for coil self-capacitance. > None are of particular value for quarter-wave helical resonators > anywhere near the 90 degree point." > > "The delusion is that the short coil is then made to operate in the > lumped element regime ...". > > That you refuse to give up on an invalid method in the face of > overwhelming evidence is amazing. > > >>What he wants me or others to do is a moot point. > > > Afraid of what you will find? The first web page above says: > "Lumped circuit theory isn't absolute truth, it's only an analytical > theory - and in these resonators we have the case where this > sophmore theory fails experimentally." Do the experiment, Tom, > and discover exactly how sophmorish you are being. > > >>I am concerned about the commonly held but very incorrect view that >>current travels through an inductor turn-by-turn, and that a loading >>inductor somehow shifts the phase of and/or level of current to "make >>up for missing degrees". > > > Tom, that's what any matching network does. Loading coils are no > exception. > > >>My only concern is people not understanding how an inductor and short >>antenna actually behaves. > > > I am concerned about you not understanding, Tom. Don't > you believe the information posted on those web pages above. Don't > you think a peer-reviewed IEEE publication that disagrees with you > is worth a second thought from you. Don't you think ignoring the > knowledge published by experts in the field is a little naive? > -- > 73, Cecil, W5DXP > > Article: 222027 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Current through coils References: <1141864325.153022.145680@p10g2000cwp.googlegroups.com> <18782-440FBF35-53@storefull-3252.bay.webtv.net> <1141907306.333725.215160@i40g2000cwc.googlegroups.com> <1210ser332cpg35@corp.supernews.com> <1141936980.983089.217740@v46g2000cwv.googlegroups.com> <1141944950.194014.62210@j33g2000cwa.googlegroups.com> Message-ID: Date: Fri, 10 Mar 2006 00:02:44 GMT w8ji@akorn.net wrote: > Cecil Moore wrote: >>But you have already started what I am asking, Tom. You >>measured a voltage phase shift of 60 degrees through a >>100uH coil at 1 MHz. The current is known to lag the voltage >>through a coil so the current phase delay is more than 60 >>degrees. I wouldn't be surprised to see it at 120+ degree >>lag in the current. So your own experiment proves you are >>wrong. How do you get away with such behavior without >>anyone noticing?. > > The only thing worth noticing is you are misrepresenting facts. > I measured current with a small current transformer, and current at > each end of the inductance was, as close as my two-channel vector > voltmeter will resolve, equal in phase and equal in level. Here are your words cut and pasted from qrz.com. > "By the way, I swept S12 phase with my network analyzer on a > 100uH inductor a few hours ago while working on a phasing > system. The phase shift through that series inductor was about > -60 or -70 degrees on 1 MHz, ... S12 is a voltage parameter. So did the coil show a "-60 or -70 degrees" voltage phase shift or not? Where does it say anything about "current with a small current transformer" in your posting? Last time I looked, a 100uH inductor was not a small current transformer. I assumed a current phase shift at first and you jumped on me about that. Now you say it was a current phase shift after all. If you want to be quoted correctly, you need to stop fibbing. Here's what I think happened in context. You were trying to prove Kraus wrong with his assertion that a 180 degree phasing coil can be thought of as 1/2WL of wire wound into a coil. You failed to realize that your posting was supporting my other point about phase shifts through coils. So you accidentally posted results that supported my side of the argument. Your lumped-circuit model predicts zero phase shift. My distributed network model predicts considerable phase shift. Your experiment yielded considerable phase shift and now you seek to deny it. However, it is there in all its glory on qrz.com for all to see. So feel free to deny it. > The only thing worth noticing is you are misrepresenting facts. I never misrepresent facts as I understand them to exist. The fact that you absolutely refuse to engage me in a technical discussion speaks volumes. If I were wrong, you would simply engage me and prove me wrong with a technical argument as you have so many others. But If I am right, I fully understand your reluctance to engage me in a technical discussion. You can start the technical discussion by explaining the EZNEC results on my web page: http://www.qsl.net/qrzgif35.gif Why are all you gurus so reluctant to discuss that topic? I have asked you guys to respond to that graphic at least half a dozen times and got only one weak reply. Why the silence? -- 73, Cecil http://www.qsl.net/w5dxp Article: 222028 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Current through coils References: <1141864325.153022.145680@p10g2000cwp.googlegroups.com> <18782-440FBF35-53@storefull-3252.bay.webtv.net> <1141907306.333725.215160@i40g2000cwc.googlegroups.com> <1210ser332cpg35@corp.supernews.com> <1141936980.983089.217740@v46g2000cwv.googlegroups.com> <1211ehep8b9i647@corp.supernews.com> Message-ID: Date: Fri, 10 Mar 2006 00:07:07 GMT Roy Lewallen wrote: > w8ji@akorn.net wrote: >> The problem with people doing work to verify this is even if several >> people measure something, Cecil will ignore results. > > Indeed. Or alter his interpretation to fit the data. I can't help but point out that you guys are refusing to engage me in any technical discussion and refusing to respond to my technical quotes. All you do is engage in desperate ad hominem attacks hoping that your guru status will prevail. That's a pretty good indication that you have already lost the technical argument and know it. -- 73, Cecil http://www.qsl.net/w5dxp Article: 222029 of rec.radio.amateur.antenna From: "Steve Nosko" Subject: Re: Impedance with T-connector? Date: Thu, 9 Mar 2006 17:49:43 -0600 Message-ID: References: <1141835066.693220.100190@j33g2000cwa.googlegroups.com> wrote in message news:1141835066.693220.100190@j33g2000cwa.googlegroups.com... > Ken, > > I guess that you are using the T-connector simply as an elbow? If this > is the case, and you put a 50 ohm load on one leg, you should leave the > other leg *open* to make the impedance be about 50 ohms. The > T-connector will give you a little bit of capacitance due to the > concentric conductors on the unused leg, but it will make little to no > difference until you hit UHF or so. > > If you put 50 ohms on one leg and a 50 ohm load on the other, Amos's > post will apply. The impedance seen by the transmitter will depend on > the length of transmission line between the T and your transmitter. > This is because the line between the T and your transmitter is no > longer properly terminated at the T end. > > With very short transmission lines, the situation is just like parallel > resistors. This means that the two loads on the T will share the > power. Regardless of the T-line length, it will be a 2:1 mismatch. If the line is 1/4 wave long, then the Tx will "see" 100 ohms. Leaving one end of the "T" open will provide no significant effects up through UHF, but it does represend a very short section of open line in parallel, which, as Dan reports, will show as a small capacitance. This, by the way is a good way to check an SWR meter for accuracy, providing, of course, the loads you use are pretty good as well. You can easily do 2:1 and 4:1 (with two "T"s and four loads) if you have them. P.s. If you needed to, and it was a good 50 ohms, you could use an antenna for one of the loads. 73, Steve, K9DCI > > This is good for things like phased yagis, but you wouldn't want to > hook an antenna to one port and a dummy to another... > > Dan, > N3OX > www.n3ox.net > Article: 222030 of rec.radio.amateur.antenna From: Roy Lewallen Subject: Re: Current through coils Date: Thu, 09 Mar 2006 16:36:17 -0800 Message-ID: <1211ig3hafcm451@corp.supernews.com> References: <1141864325.153022.145680@p10g2000cwp.googlegroups.com> <18782-440FBF35-53@storefull-3252.bay.webtv.net> <1141929188.910581.171220@p10g2000cwp.googlegroups.com> Gene Fuller wrote: > > Cecil Moore wrote: >>. . . >> "... - no wave interferrence and no standing waves can be >> present on lumped elements. The problem has been that many >> experimenters working with self-resonant helices have >> PURSUED THE CONCEPT OF COIL SELF- >> CAPACITANCE WITHOUT REALLY UNDERSTANDING >> WHERE THE NOTION COMES FROM OR WHY IT WAS >> EVER INVOKED BY ENGINEERS. For that, they will have >> to go read R.W.P. King's wonderful old book, "Electromagnetic >> Engineering, McGraw-Hill, 1945. ... On page 465, the Harvard >> Professor points out that, for coils whose *wire length* exceeds >> 1/6 wavelength, ...'an adequate representation of the reactance >> of a coil with a nonuniformly distributed currentr is NOT >> POSSIBLE in terms of a coil with a uniform current [a lumped >> element inductance] ...' Period. Resonant FIELDS present >> surprises to engineers with limited training." >> >> Certainly sounds like he is talking about you, Tom. "Electronic >> Engineering" was written before you were born. Why are you >> ignorant of the technical facts presented in it? I have this book. The condition for the quoted result isn't simply that the length of wire in the coil be adequately long, but also that the coil be wound loosely enough so that the coupling between turns is poor enough to allow a particular nonuniform current distribution. It applies to a "loosely wound helix." The quote is within a section titled "'Lumped' Constants in Near-zone circuits", which contains a detailed analysis of just what conditions can cause an inductor to have unequal input and output currents, but primarily how the currents can be unequal even in the absence of an external field. In particular, the author describes an inductor in which the coupling between turns isn't sufficient to force equal currents at the coil ends. Qualitatively, this should be pretty obvious: If we begin with a long wire (in terms of wavelength), the current will vary along its length. As we wind it into a loose coil, mutual coupling between turns will create inductance and make the current more uniform, but with a distribution still resembling that of the straight wire. It's this situation that the quotation applies to -- an inductor so loosely wound that its current distribution resembles a straight wire more than an inductance. He does go on to say that if the winding is tighter but still not ideal, the resulting non-uniform current, which has a different distribution (greater at the center than at the ends), can be modeled by means of a lumped self capacitance. Only if we have perfect coupling between turns (as a toroid very nearly represents) will we truly have equal currents at input and output, for the reasons Tom recently explained. This is the idealized inductance which some of the contributers to this discussion are having trouble understanding. The mathematical treatment in King is quite complex. But nowhere does he mention any traveling, reflected, or standing current, power, or energy waves, or that an inductance behaves any differently in an antenna than in a lumped circuit. It simply isn't necessary or relevant to explaining the operation of either an ideal or non-ideal inductor. Nor does he dispute the fact that the currents into and out of an ideal inductance are equal. And of course there's no mention of the mysterious "resonant fields" which probably do surprise engineers, as does the metaphysics being promoted here. Roy Lewallen, W7EL Article: 222031 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Current through coils References: <1141864325.153022.145680@p10g2000cwp.googlegroups.com> <18782-440FBF35-53@storefull-3252.bay.webtv.net> <1141929188.910581.171220@p10g2000cwp.googlegroups.com> <1211ig3hafcm451@corp.supernews.com> Message-ID: Date: Fri, 10 Mar 2006 02:12:08 GMT Roy Lewallen wrote: > It applies to a "loosely wound helix." Please define the point at which a "loosely wound helix" with a varying current turns into this lumped-circuit device that forces equal currents through the coil. Is a 75m bugcatcher coil a "loosely wound helix" or a "lumped-circuit"? (My 75m bugcatcher coil is about 1/6 wavelength of wire.) > Only if we have perfect coupling between turns (as a toroid > very nearly represents) will we truly have equal currents at input and > output, for the reasons Tom recently explained. This is the idealized > inductance which some of the contributers to this discussion are having > trouble understanding. Unfortunately, an idealized inductance is like a lossless transmission line - it exists only in the human mind. What I would like to know is what is the real-world phase shift through your toroidal inductor when there is only a traveling wave (no standing wave). We can then use the laws of reflection physics to determine what effect that phase shift has on the amplitude of the standing wave current which is the phasor sum of the forward current and reflected current. I'm actually going to make those measurements as soon as I get off my old lazy ass. Seems to me that although a toroidal current pickup may not have the same magnitude characteristics because of variations in the permeability, the phase would suffer no such effects. Am I correct on that point? I'm somewhat handicapped in having no current probes for my 100 MHz Leader and acquiring them would put a big dent in my Social Security check. :-) What I am toying with is a 6m rhombic. I could run it as a terminated traveling-wave antenna or unterminate it and have a standing-wave antenna. I could move all kinds of coil(s) up and down the the elements to place them at nodes or loops or in-between and take measurements. What do you think? -- 73, Cecil http://www.qsl.net/w5dxp Article: 222032 of rec.radio.amateur.antenna From: "Jerry Martes" References: <1141864325.153022.145680@p10g2000cwp.googlegroups.com> <18782-440FBF35-53@storefull-3252.bay.webtv.net> <1141929188.910581.171220@p10g2000cwp.googlegroups.com> <1211ig3hafcm451@corp.supernews.com> Subject: Re: Current through coils Message-ID: Date: Fri, 10 Mar 2006 03:12:11 GMT Hi Cecil I have a HP8405A Vector Voltmeter I'll give you and even pay the shipping if that is of any help with the measurements. Jerry "Cecil Moore" wrote in message news:Yf5Qf.28277$2O6.3764@newssvr12.news.prodigy.com... > Roy Lewallen wrote: >> It applies to a "loosely wound helix." > > Please define the point at which a "loosely wound helix" with > a varying current turns into this lumped-circuit device that > forces equal currents through the coil. Is a 75m bugcatcher > coil a "loosely wound helix" or a "lumped-circuit"? > (My 75m bugcatcher coil is about 1/6 wavelength of wire.) > >> Only if we have perfect coupling between turns (as a toroid very nearly >> represents) will we truly have equal currents at input and output, for >> the reasons Tom recently explained. This is the idealized inductance >> which some of the contributers to this discussion are having trouble >> understanding. > > Unfortunately, an idealized inductance is like a lossless transmission > line - it exists only in the human mind. What I would like to know is > what is the real-world phase shift through your toroidal inductor when > there is only a traveling wave (no standing wave). We can then use > the laws of reflection physics to determine what effect that phase > shift has on the amplitude of the standing wave current which is the > phasor sum of the forward current and reflected current. I'm actually > going to make those measurements as soon as I get off my old lazy ass. > > Seems to me that although a toroidal current pickup may not have the > same magnitude characteristics because of variations in the permeability, > the phase would suffer no such effects. Am I correct on that point? > I'm somewhat handicapped in having no current probes for my 100 MHz > Leader and acquiring them would put a big dent in my Social Security > check. :-) > > What I am toying with is a 6m rhombic. I could run it as a terminated > traveling-wave antenna or unterminate it and have a standing-wave > antenna. I could move all kinds of coil(s) up and down the the elements > to place them at nodes or loops or in-between and take measurements. > What do you think? > -- > 73, Cecil http://www.qsl.net/w5dxp Article: 222033 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Current through coils References: <1141864325.153022.145680@p10g2000cwp.googlegroups.com> <18782-440FBF35-53@storefull-3252.bay.webtv.net> <1141907306.333725.215160@i40g2000cwc.googlegroups.com> <1210ser332cpg35@corp.supernews.com> <1141936980.983089.217740@v46g2000cwv.googlegroups.com> <1141944950.194014.62210@j33g2000cwa.googlegroups.com> <1141959810.308504.202590@u72g2000cwu.googlegroups.com> Message-ID: <847Qf.74776$PL5.71405@newssvr11.news.prodigy.com> Date: Fri, 10 Mar 2006 04:16:04 GMT w8ji@akorn.net wrote: > Please stop trying to blame your mistakes on me! It's not my fault you > assumed more than you read! I've been telling you all along current at > each end of ANY small inductor has the same phase. Please define "small" in terms of the number of degrees of phase shift measured using a traveling wave signal. > Don't accuse me of lying because you made up a theory and it is dead > wrong! It isn't MY fault you painted yourself in a corner by adjusting > your theories to suit what you thought was said, when it wasn't even > said. Your diversions are comical and obvious, Tom. Thanks for the laugh. > If you stayed away from personal attacks I would converse with you. Pot, Kettle. Kettle, Pot. Tom, your personal attacks are legend throughout the internet and world wide web. I know hams who are too terrified to respond to you even when you are wrong. > 1.) We really can't have a good conversation until you stop the > constant personal attacks, and until we agree on a few basics. Hard to accomplish since you define being proven technically wrong as a personal attack. > 2.) You claim Roy measured current that doesn't flow. That area needs > addressed. Please explain how a net current with a fixed constant non-rotating phase can possibly flow. Please explain how a wire with 1 amp flowing in one direction and 1 amp flowing in the other direction supports a net charge flow. > 3.) You also claim significant current phase shift exists between the > terminals of a compact inductor operated well below self-resonance. Please define "compact" in terms of the number of degrees of phase shift measured using a traveling wave. > It's very simple to measure current and voltage and the phase > relationships in a two terminal device and prove you are wrong. I've got many technical references that disagree. If you can do that, why haven't you done that? > The current flowing into one end and out of the other end of a small > lumped inductor operated far below self-resonance is essentially equal > in both phase and amplitude. Please define "small" as the number of degrees of phase shift measured using a traveling wave. > You say it isn't, I say it is, and I can > prove it beyond any doubt to any open minded person. Here, you are just out and out lying since I never said that. Want to bet $1000 that you can prove I ever said that? I didn't think so. What is with this compulsion you have to lie about what I have said? Can't you win a technical argument without lying? > I say I can easily build a loading coil that acts the same way. I can > replace 40 or 60 degrees of electrical height with an inductor that has > virtually no phase shift in current between the two terminals, and > virtually the same current level. I can prove that also. I seriously doubt that. Please measure the phase shift using a traveling wave through any coil that accomplishes that function. I suspect you are being fooled by the current loop located inside the coil and the fact that you have been ignorantly been measuring the net standing wave current which is essentially irrelevant. > I'm just not sure I can prove anything to someone who thinks a current > transformer measures current that doesn't flow! I explained it to you, Tom, in another posting. If you don't understand it, you need technical help. At a fixed point on a wire (where no net current or net charge is flowing) that is experiencing a constant exchange of H-field energy with E-field energy every cycle, a toroidal pickup coil will certainly report the results of that orthogonal energy exchange between the fields even though there is no lateral flow of net current or net charge. That's why a standing-wave dipole radiates broadside and a traveling-wave dipole is an end-fire. What school did you say you attended? -- 73, Cecil http://www.qsl.net/w5dxp Article: 222034 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Current through coils References: <1141864325.153022.145680@p10g2000cwp.googlegroups.com> <18782-440FBF35-53@storefull-3252.bay.webtv.net> <1141929188.910581.171220@p10g2000cwp.googlegroups.com> <1211ig3hafcm451@corp.supernews.com> Message-ID: Date: Fri, 10 Mar 2006 04:23:03 GMT Jerry Martes wrote: > I have a HP8405A Vector Voltmeter I'll give you and even pay the shipping > if that is of any help with the measurements. Wow, thanks for the offer. That would certainly be more accurate than eyeballing an o'scope. Do you think the use of such would prove me right or wrong? Does the VV compare two signals and report the phase difference? Are the probes differential or coaxial? I've never used a VV. -- 73, Cecil http://www.qsl.net/w5dxp Article: 222035 of rec.radio.amateur.antenna Date: Thu, 09 Mar 2006 23:28:12 -0500 From: jawod Subject: Safety ground versus RF ground for a 2nd Floor shack Message-ID: <26f31$44110069$42a1bfc2$15706@FUSE.NET> I know this has been addressed on the group before but I remain confused. I will string a dipole in the trees. The coax shield will be earth grounded, as well as the balun and lightening arrestor. Now, in the 2nd floor shack, I've read that running a ground line from equipment 15 feet or more (in this case) to an earth ground will bring RF into the shack and be a potent source for TVI, etc. My choice, then, is to use the ground on the mains. Given that the shield is earth grounded on the antenna and the equipment is grounded to the mains, isn't this a good scenario for ground loop? Seems like a catch-22. My own gut says safety first, lower risk of RF issues after-the-fact by ? what ? I remember suggestions of coiling the ground wire in an RF choke, multiple ground lines of various lenghts to mess with harmonics. Ferrite beads? Chicken blood and a black cat? John Article: 222036 of rec.radio.amateur.antenna From: Chris W <1qazse4@cox.net> Subject: Re: 1n21 diode housing References: <1141683523.401360.217420@i40g2000cwc.googlegroups.com> <0c5Pf.29731$2c4.26947@dukeread11> <1141799502.565371.230380@z34g2000cwc.googlegroups.com> Message-ID: <_k7Qf.30551$2c4.20716@dukeread11> Date: Thu, 09 Mar 2006 22:33:59 -0600 Litzendraht wrote: >>Yep, that is exactly what I am looking for, with no luck so far. I have >>some 1.2, 1.6 and 2.4 ghz antennas I want to tune. >>Chris W >>KE5GIX >> >> > > >Chris, > > If it's exactly what you're looking for, I have a hand full of these >things. It's a Sage 1021H adapter and has a front end that looks like a >UG 21 and a BNC on the rear. The BNC unscrews and you install the 1N21 >like a .22 round , and screw it back together. It's not a tiny assembly >and measures 62mm in length (just shy of 2.5 inches). > >I found it listed on line at A-Comm Electronics and they say it's good >to 12.4 kmc. > >If it's something you really could use, I could send you a couple at a >fair price. > >But I'm surprised that anyone nowdays would be using a full sized type >N connector for anything other than moderate powered transmitting. > > I had to do some research to find out that a UG 21 is just and N connector. I'm not sure why you are surprised people are using them. The are about the same size connector as a UHF which is very common in ham radio, and the N is a much better connector. I put N connectors on all of my antennas, especially if they are going to be out side. But yes I would be interested in one of those Sage 1021H adapters. I have a few extra 1N21 diodes if you want to make a trade or I can just send money. Do you take paypal? Let me know what you want for them. -- Chris W KE5GIX Gift Giving Made Easy Get the gifts you want & give the gifts they want One stop wish list for any gift, >from anywhere, for any occasion! http://thewishzone.com Article: 222037 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Current through coils References: <1141864325.153022.145680@p10g2000cwp.googlegroups.com> <18782-440FBF35-53@storefull-3252.bay.webtv.net> <1141929188.910581.171220@p10g2000cwp.googlegroups.com> <1211ig3hafcm451@corp.supernews.com> <6C7Qf.30158$G%2.26187@trnddc07> Message-ID: <4T7Qf.74779$PL5.8875@newssvr11.news.prodigy.com> Date: Fri, 10 Mar 2006 05:10:24 GMT Jerry Martes wrote: > It sure would be worth the effort to ship it to you if you'd like to have > it. I hate to accept it for free. Maybe I could just borrow it for awhile? > I have such a high respect for Roy and Wes that it is not possible for me > to think they'd both be wrong while in agreement. So why are you offering a free VV to someone they both hate? :-) -- 73, Cecil http://www.qsl.net/w5dxp Article: 222038 of rec.radio.amateur.antenna From: "Jerry Martes" References: <1141864325.153022.145680@p10g2000cwp.googlegroups.com> <18782-440FBF35-53@storefull-3252.bay.webtv.net> <1141929188.910581.171220@p10g2000cwp.googlegroups.com> <1211ig3hafcm451@corp.supernews.com> <6C7Qf.30158$G%2.26187@trnddc07> <4T7Qf.74779$PL5.8875@newssvr11.news.prodigy.com> Subject: Re: Current through coils Message-ID: <4U8Qf.22779$eP4.5538@trnddc05> Date: Fri, 10 Mar 2006 06:19:44 GMT "Cecil Moore" wrote in message news:4T7Qf.74779$PL5.8875@newssvr11.news.prodigy.com... > Jerry Martes wrote: >> It sure would be worth the effort to ship it to you if you'd like to have >> it. > > I hate to accept it for free. Maybe I could just borrow it > for awhile? > >> I have such a high respect for Roy and Wes that it is not possible for me >> to think they'd both be wrong while in agreement. > > So why are you offering a free VV to someone they both hate? :-) > -- > 73, Cecil http://www.qsl.net/w5dxp Hi Cecil There is no reason to ever return any of the stuff I send out. I actually enjoy knowing that someone appreciates this stuff. I dont pay $$ for it. It gets surplused by the government. My buddy buys it in bulk. I am able to refurbish alot of the surplus he buys, like 100 KW gen-sets, so he can re-sell the units back to them. Since I enjoy learning how to fix the broken stuff, I dont charge for my time. So, he lets me sort thru his "scrap piles". Everyone wins. But, I dont get to watch much TV because I keep too busy learning how to fix the stuff. Send me your shipping address. The HP 8405A will be in the mail within a day after I get the address. Do you have any use for a HP 8660 signal generator main frame, *no* plug-ins? That would sure be a nice generator to go with a Vector Voltmeter. I have 5 main frames but I havent been able to win an eBay bid for the plug-ins. Jerry Article: 222039 of rec.radio.amateur.antenna From: "Jerry Martes" References: <1141864325.153022.145680@p10g2000cwp.googlegroups.com> <18782-440FBF35-53@storefull-3252.bay.webtv.net> <1141907306.333725.215160@i40g2000cwc.googlegroups.com> <4nh012l7ogdc07e4vcciuj0l21usbbtpnp@4ax.com> Subject: Re: Current through coils Message-ID: Date: Fri, 10 Mar 2006 06:24:48 GMT "Wes Stewart" wrote in message news:el4212hq0bk4592g8j06u5q04ki1n0elhl@4ax.com... > On Fri, 10 Mar 2006 01:14:18 GMT, Cecil Moore wrote: > >>Wes Stewart wrote: >>> Why do you persist at doing this? >>> >>> My post was in response to someone else and you feel it necessary to >>> jump in with the same old bafflegab. >> >>This is a public forum. Why do you not respond to my posting on >>a technical level instead of resorting to an ad hominem attack? >>I have tons of technical references to support my position. >> >>> Clearly, you were too busy trying to frame an argument to actually >>> read what I wrote. >> >>I only respond to portions I disagree with, Wes. Why can't >>you and I have a simple, point by point, technical discussion? > > Which points? You are the master at selective editing. For example > you stated: > > "Your graphs show standing wave current which doesn't flow...blah > blah" > > When I show otherwise, snip, gone without reply. > >> >>> "We" need to plot no such thing. You may have such a need; I do not. >> >>You, nor your cohorts, are likely to understand what's really >>happening until you take a look at the individual underlying >>currents that superpose to form the standing wave current which >>doesn't flow at all since its phase angle is fixed at zero degrees. > > I have no "cohorts" here. This isn't the "Let's get Cecil" gang. > >> >>Isn't a bunch of IEEE PhD's saying that "the lumped-circuit model >>fails in a standing-wave environment", enough evidence for you to >>consider that they know what they are talking about? > > I've worked with lots of PhD's. Hell I even had one working for me > and his was in Nuclear Physics from Trinity College at Oxford. He was > a lovely old guy, the quintessential Einstein type, who couldn't find > his way to the men's room without directions. Another, younger one > was so impressed with himself, it was impossible to have a > conversation with him without him saying, "When I was working on my > thesis..." > > Pass him in the hall and say, "Nice day today." > > He would reply, "Yes, it is but I remember a day back when I was > working on my thesis..." > > Sorry, "A bunch of IEEE PhD's" impresses me less than a handful of the > guys posting here. > Hi Wes The more I read your posts the more I like the way you think. Jerry Article: 222040 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Current through coils References: <1141929188.910581.171220@p10g2000cwp.googlegroups.com> <1211ig3hafcm451@corp.supernews.com> <6C7Qf.30158$G%2.26187@trnddc07> <4T7Qf.74779$PL5.8875@newssvr11.news.prodigy.com> Message-ID: Date: Fri, 10 Mar 2006 11:36:11 GMT Wes Stewart wrote: > Cecil Moore wrote: >>So why are you offering a free VV to someone they both hate? :-) > > I don't hate you. While I shook your hand at Flagstaff once, I don't > know you well enough personally to get all worked about you one way or > another. This is Usenet, not the real world. No sense taking it too > seriously. I wasn't serious, Wes. That's why the smiley face. I apologize if my humor irritates anyone. -- 73, Cecil http://www.qsl.net/w5dxp Article: 222041 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Current through coils References: <18782-440FBF35-53@storefull-3252.bay.webtv.net> <1141929188.910581.171220@p10g2000cwp.googlegroups.com> <1211ig3hafcm451@corp.supernews.com> Message-ID: Date: Fri, 10 Mar 2006 11:51:51 GMT Wes Stewart wrote: > The VVM probes are comprised of a quad diode sampling bridge followed > by an FET amplifier. They are nominally coaxial, although without the > BNC adapters, they have an exposed pin (very delicate) and at lower > frequencies they can be used much as a high impedance scope probe is > used. Thanks, Wes. When you say "lower frequencies", does that include 4 MHz? > The instrument uses a phase-locked oscillator to drive the samplers > with the "A" probe being the reference. One meter can be switched to > display the amplitude of either channel and the second meter reads the > phase difference between them. I was planning to use toroidal pickups and a Lissajous figure for the phase measurement. Did you know "Lissajous figure" is described in my 1957 ARRL Handbook but not in my 2000 ARRL Handbook? My main concern is how to ensure there are no reflections present during the measurement. I need to put the 75m bugcatcher coil in an RF loop where current is flowing in only one direction. That's easy to draw on paper but I'm concerned about it. How would you set it up? -- 73, Cecil http://www.qsl.net/w5dxp Article: 222042 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Current through coils References: <1141864325.153022.145680@p10g2000cwp.googlegroups.com> <18782-440FBF35-53@storefull-3252.bay.webtv.net> <1141907306.333725.215160@i40g2000cwc.googlegroups.com> <4nh012l7ogdc07e4vcciuj0l21usbbtpnp@4ax.com> Message-ID: Date: Fri, 10 Mar 2006 12:16:20 GMT Wes Stewart wrote: > Cecil Moore wrote: > "Your graphs show standing wave current which doesn't flow...blah > blah" > > When I show otherwise, snip, gone without reply. Sorry, I completely missed it. I'll go back and try to find it. > Sorry, "A bunch of IEEE PhD's" impresses me less than a handful of the > guys posting here. Have you looked at the articles on the web pages I posted? Here's a funny quote, not previous quoted from: http://www.ttr.com/corum/index.htm "What frequency did you get in step 5? ... Is the difference within engineering accuracy ... less than 5%? If the answer is yes, then you may confidently use lumped-element modeling. However, if the answer is no, then, from the halls of Valhalla, old Wotan, himself, is thundering out over the battlements, '#*@&%!! ... Thor, you dumdum! You CAN'T use lumped circuit modeling!' ... [The coil has standing waves and is behaving as a distributed resonator.]" In case you missed it, here's what Walter Maxwell had to say about the subject: >> "If an inductance is in series with a line that has >> reflections, the current will NOT be the same at both >> ends of the inductor." >> >> "Consequently, circuit analysis will not work when both >> forward and reflected currents are present in a lumped >> circuit." -- 73, Cecil http://www.qsl.net/w5dxp Article: 222043 of rec.radio.amateur.antenna From: "Dick, AA5VU" Subject: Dipole Extension Message-ID: Date: Fri, 10 Mar 2006 12:55:55 GMT I have an old (but very good) W9INN 40/80 dipole. The only problem is it is cut for the upper phone band (centered at ~7.200) for 40 meters and I now do most operating in the lower portion of the band and would like to move the center to about 7.100 MHz. The 40 meter portion of the antenna is all soldered so I cannot just unwrap and extend it bit. Any suggestions on the best way to add a extension and how much to add? I have been thinking about cutting it and soldering in an X?-inch splice. Does the extension wire have to really match? Dick AA5VU Article: 222044 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Current through coils References: <1141864325.153022.145680@p10g2000cwp.googlegroups.com> <18782-440FBF35-53@storefull-3252.bay.webtv.net> <1141907306.333725.215160@i40g2000cwc.googlegroups.com> <1210ser332cpg35@corp.supernews.com> <1141936980.983089.217740@v46g2000cwv.googlegroups.com> <1141944950.194014.62210@j33g2000cwa.googlegroups.com> <1141959810.308504.202590@u72g2000cwu.googlegroups.com> <847Qf.74776$PL5.71405@newssvr11.news.prodigy.com> <1141983043.843913.310960@u72g2000cwu.googlegroups.com> Message-ID: Date: Fri, 10 Mar 2006 13:35:14 GMT w8ji@akorn.net wrote: > Cecil Moore wrote: >>Please explain how a net current with a fixed constant >>non-rotating phase can possibly flow. Please explain >>how a wire with 1 amp flowing in one direction and 1 amp >>flowing in the other direction supports a net charge flow. > > Once again this indicates you are not familiar or comfortable with > basics, and have gotten ahead of yourself by going off somehwre in a > land of reflected waves. Now you are confused, and can't make sense of > basics. As readers can observe for themselves, you avoided answering the question and you instead turned it into personal insults. > The generator sees a reactive load. When the generator sees a reactive > load, current and voltage are no longer in step. This is true all > through the system from source to load. I didn't ask or say anything about voltage. The fact that you refuse to answer my technical questions speaks volumes. >>Please define "compact" in terms of the number of degrees >>of phase shift measured using a traveling wave. > > Phase shift in what Cecil? The measured phase shift is in a traveling wave through a 75m bugcatcher coil. How long does it take the traveling wave current to flow from one end of the coil to the other? Your lumped-circuit model presupposes instantaneous current flow for traveling waves. Let's measure the current delay in a traveling wave to see if your model is correct. If it is not correct, it is useless. You cannot even begin to understand the problem if you don't know that basic phase shift. I'm willing to bet that my 75m bugcatcher coil has at least a 40 nanosecond delay on 4 MHz which is a 60 degree current phase shift. If that measured delay is in the ballpark of 40 nanoseconds or more, it proves that your lumped-circuit model has failed and your invalid proof is presupposed in the invalid model. You cannot use a model that presupposes instantaneous current flow to prove that the current flow is instantaneous. You cannot use a model that presupposes constant current magnitude to prove that the current has constant magnitude. > You keep trying to define the "inductor" in terms of degrees related to > standing waves ... Not true, Tom, and just shows how confused you are about what I have said. For the Nth time: The phase of the standing wave current doesn't change up and down the entire length of a 1/2WL thin dipole. Why would anyone expect it to change at the ends of a loading coil? As far as I am concerned we can drop any discussion of standing wave current phase. It is meaningless. The phase that Roy measured was standing wave phase. It was already known and is completely irrelevant. I asked Roy to measure the traveling wave phase shift. He didn't. > I have done it and told you how, you ignore it. Roy has done it and > told you how, you ignore it. You guys are measuring standing wave current that doesn't flow and doesn't change phase. Your measurements are completely meaningless and your flawed model has you hoodwinked. > The only way to get confused on that is if someone doesn't understand > behavior of the basic component, gets in over his head and confuses > himself trying to use a tool that doesn't work, and then lashes out at > others and refuses to listen. That's an exact description of you and your lumped circuit analysis in a standing wave environment. Do you disagree with Walter Maxwell? > Walt wrote: >> "If an inductance is in series with a line that has reflections, >> the current will NOT be the same at both ends of the inductor." >> >> "Consequently, circuit analysis will not work when both forward >> and reflected currents are present in a lumped circuit." The component is not the problem, Tom. The problem seems to be your feigning of total ignorance of the laws of reflection physics in order to avoid discussing the real problem. > There you go again! Back to traveling and standing waves. Yes, you are never going to understand what I am saying about standing-wave antennas until you discuss traveling and standing waves on the standing-wave antenna. Your lumped-circuit model is known to fail in the presence of standing waves. > There you go again, back to the lowest form of debate. If you can't > understand something or get trapped, just call the other guy a liar. No, it's a lot simpler than that. When you lie about something I said, I call you a liar. > You very clearly said current in each terminal of the inductor has a > different phase shift several times in your posts. One more time. The standing wave current does NOT change phase at the ends of the coil. The standing wave current essentially does not change phase unless a dipole is longer than 1/2WL. The phase of the standing wave current is totally irrelevant. The forward traveling-wave current experiences a delay through the coil. The reflected traveling-wave current experiences a delay through the coil. This delay can be measured on the bench. If the delay is not negligible, your lumped-circuit model is useless because it presupposes a delay of zero. > I can't understand what you are saying or what your point is, ... Please don't insult my intelligence or yours. Every one of us performed those experiments on the bench in college. Exactly what is it about bench measuring the RF current delay through a coil that you don't understand? > Maybe someone else can help me with your last statement. Do you even know what a standing wave current loop is? > Maybe someone else on this group can explain or understand what you are > trying to say. You must have missed EE203. :-) What is it about a continuous exchange of energy between the E-field and H-field at a fixed point on an antenna wire that you don't understand? That's just a characteristic of standing waves. Roy has used the same argument in the past to try to prove that reflected energy doesn't flow. But's it's the standing wave energy that doesn't flow. -- 73, Cecil http://www.qsl.net/w5dxp Article: 222045 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Current through coils References: <1141864325.153022.145680@p10g2000cwp.googlegroups.com> <18782-440FBF35-53@storefull-3252.bay.webtv.net> <1141907306.333725.215160@i40g2000cwc.googlegroups.com> <4nh012l7ogdc07e4vcciuj0l21usbbtpnp@4ax.com> <1141994153.891695.287240@j33g2000cwa.googlegroups.com> Message-ID: <5TfQf.44145$F_3.10152@newssvr29.news.prodigy.net> Date: Fri, 10 Mar 2006 14:16:33 GMT w8ji@akorn.net wrote: > Cecil Moore wrote: >>In case you missed it, here's what Walter Maxwell had to say >>about the subject: >> >> >> "If an inductance is in series with a line that has >> >> reflections, the current will NOT be the same at both >> >> ends of the inductor." >> >> >> >> "Consequently, circuit analysis will not work when both >> >> forward and reflected currents are present in a lumped >> >> circuit." > > Cecil, I really think you should let Walt speak for himself. Sorry, I don't care what you think. You and I (and Walt) know exactly who distorted the facts. > If anyone really thinks that as a stand-alone statement, it is not > correct. I suspect he didn't get the full story or wasn't following a > discussion closely, or you have snipped something out of context. It's > very easy to take small areas out of context and make it seem like > someone is saying something they are not. Those are Walt's exact words, not mine. If you don't believe me, send him an email and ask him. > The behavior of any small two-terminal component REQUIRES currents to > be essentially equal. It's only when the component has a third > significant path to the outside world that currents can be unequal. Wrong! Wrong! Wrong! Your lumped-circuit model presupposes that the currents are equal so you are begging the question. YOU CANNOT USE YOUR MODEL TO PROVE ITS OWN PRESUPPOSITIONS. I see you haven't yet read what Dr. Corum had to say on that subject. http://www.ttr.com/corum/index.htm > If I have a small capacitor, current flowing in one lead is equal to > current flowing out the other and the phase of each current is exactly > equal. Same for an inductor. Sorry, that's just not true for inductors. In the real world, there is a traveling wave current delay through the coil that can easily be measured on the bench. That delay converts directly to a phase delay. You are simply mistaken, hoodwinked by your lumped-circuit model, which presupposes the proof of what you say above. You are once again, begging the question and assuming the proof without having proved anything. > That's not a guess, that's a rule of how things always behave. BS, Tom. That's a rule from a model known to fail in the presence of standing waves. Models existing in your mind don't dictate reality. It is supposed to be just the opposite. > I'm wondering if the real problem is some people spend too much time > with transmission lines and antenna and not enough time with circuit > components, and become rusty? The real problem is that you are looking for your keys under the streetlight instead of in the dark where you lost them. The real problem is that you are doing the same thing as the naive ham who tries to measure feedpoint impedance with an ohm-meter. The real problem is that you are using a tool known to fail under the conditions in which you are trying to use it. THE LUMPED-CIRCUIT MODEL FAILS IN THE PRESENCE OF STANDING WAVES! I know that. Walt knows that. Dr. Corum knows that. A number of lurkers on this newsgroup know that. Nikola Tesla obviously knew that in his 1897 patent application. > In any event, you do enough damage to people's reputations Cecil. > Please leave Walt alone. He will speak for himself if he likes. Please mind your own business. I have Walt's permission to quote his stuff. If he ever asks me to stop quoting him, I will. One wonders if your attitude would be different if Walt agreed with you? :-) -- 73, Cecil http://www.qsl.net/w5dxp Article: 222046 of rec.radio.amateur.antenna From: Bob Bob Subject: Soil dielectric constand and conductivity for East Texas Message-ID: <6kf8e3-hhc.ln1@p400bob.personal.cox.net> Date: Fri, 10 Mar 2006 08:38:29 -0600 Hi Y'all! (said with a strange Australian accent!) Am doing so NEC work for my QTH and need to get an idea of the ground conditions here. I started with the "Rich soil" of Dallas>Lincoln but was advised that it was more clay and likely to be typical of that in central VA. Any information helpful. Cheers Bob W5/VK2YQA The 4NEC2 manual extract is attached inline below; Pastoral, low hills, rich soil, typical from Dallas, TX, to Lincoln, NE 0.0303 20 Very Good Pastoral, low hills, rich soil, typical of OH and IL 0.01 14 Good Flat country, marshy, densely wooded, typical of LA near the Mississippi River 0.0075 12 Pastoral, medium hills, and forestation, typical of MD, PA, NY (exclusive of mountains and coastline) 0.006 13 Pastoral, medium hills, and forestation, heavy clay soils, typical of central VA 0.005 13 Average Rocky soil, steep hills, typically mountainous 0.002 12-14 Poor Sandy, dry, flat, coastal 0.002 10 Article: 222047 of rec.radio.amateur.antenna From: John Ferrell Subject: Re: Dipole Extension Message-ID: References: Date: Fri, 10 Mar 2006 15:41:30 GMT I am not familiar with your 40/80 dipole, I assume it is a trap arrangement. The 1/2 wave difference on 40M of 7.2 and 7.1mhz is only about a foot. The change in a DIPOLE at 40M would be difficult to measure. I would not change it. Do you have an indication that it needs adjustment? On Fri, 10 Mar 2006 12:55:55 GMT, "Dick, AA5VU" wrote: >I have an old (but very good) W9INN 40/80 dipole. The only problem is >it is cut for the upper phone band (centered at ~7.200) for 40 meters >and I now do most operating in the lower portion of the band and would >like to move the center to about 7.100 MHz. The 40 meter portion of the >antenna is all soldered so I cannot just unwrap and extend it bit. > >Any suggestions on the best way to add a extension and how much to add? > >I have been thinking about cutting it and soldering in an X?-inch >splice. Does the extension wire have to really match? > >Dick AA5VU John Ferrell W8CCW Article: 222048 of rec.radio.amateur.antenna From: Bob Miller Subject: Re: Dipole Extension Message-ID: References: Date: Fri, 10 Mar 2006 15:58:59 GMT On Fri, 10 Mar 2006 12:55:55 GMT, "Dick, AA5VU" wrote: >I have an old (but very good) W9INN 40/80 dipole. The only problem is >it is cut for the upper phone band (centered at ~7.200) for 40 meters >and I now do most operating in the lower portion of the band and would >like to move the center to about 7.100 MHz. The 40 meter portion of the >antenna is all soldered so I cannot just unwrap and extend it bit. > >Any suggestions on the best way to add a extension and how much to add? > >I have been thinking about cutting it and soldering in an X?-inch >splice. Does the extension wire have to really match? > >Dick AA5VU I've added extensions via an alligator clip with a piece of wire attached, and then shorten that wire until you get a good match. bob k5qwg Article: 222049 of rec.radio.amateur.antenna From: "Frank" References: <6kf8e3-hhc.ln1@p400bob.personal.cox.net> Subject: Re: Soil dielectric constand and conductivity for East Texas Message-ID: Date: Fri, 10 Mar 2006 16:08:42 GMT "Bob Bob" wrote in message news:6kf8e3-hhc.ln1@p400bob.personal.cox.net... > Hi Y'all! (said with a strange Australian accent!) > > Am doing so NEC work for my QTH and need to get an idea of the ground > conditions here. > > I started with the "Rich soil" of Dallas>Lincoln but was advised that it > was more clay and likely to be typical of that in central VA. > > Any information helpful. > > Cheers Bob W5/VK2YQA > > > > The 4NEC2 manual extract is attached inline below; > > > Pastoral, low hills, rich soil, typical from > Dallas, TX, to Lincoln, NE 0.0303 20 Very Good > > Pastoral, low hills, rich soil, typical of OH > and IL 0.01 14 Good > > Flat country, marshy, densely wooded, typical > of LA near the Mississippi River 0.0075 12 > > Pastoral, medium hills, and forestation, typical > of MD, PA, NY (exclusive of mountains and > coastline) 0.006 13 > > Pastoral, medium hills, and forestation, heavy > clay soils, typical of central VA 0.005 13 Average > > Rocky soil, steep hills, typically mountainous 0.002 12-14 Poor > > Sandy, dry, flat, coastal 0.002 10 Bob, According to my 1977 edition of "Reference Data for Radio Engineers" Soil conductivity along the south bank of the red river is 30mS/m (Most of the OK side is shown as 15 mS/m). Since the map is not very detailed, and without going to the extent of graphic overlays, it seems that Dallas is in a region of lower conductivity at 15 mS/m. If you are interested I can scan the map for you. I went to the trouble of measuring my soil conductivity; using the "4 rod method", with 60 Hz AC, as per the ARRL handbook (Measured 52 mS/m in Calgary). I believe I have JPEGs of the relevant pages someplace. Also some guys I was working with, a couple of years ago, devised a method of measuring the complex permittivity with a capacitor structure. There were some problems with the method, which they eventually corrected. The information was required to analyze short range VHF transmission underground. 73. Frank, VE6CB Article: 222050 of rec.radio.amateur.antenna From: "NA" References: <_1GPf.17539$992.17494@tornado.socal.rr.com> Subject: Re: Military ships fan antenna Message-ID: Date: Fri, 10 Mar 2006 16:46:42 GMT Thanks for your input. Jim N6PJQ "NA" wrote in message news:_1GPf.17539$992.17494@tornado.socal.rr.com... > Can anyone tell me about "fan antennas" like those used on the large navy > ships. > > Thanks Jim N6PJQ > > > Article: 222051 of rec.radio.amateur.antenna From: "Cecil Moore" References: <1141864325.153022.145680@p10g2000cwp.googlegroups.com> <18782-440FBF35-53@storefull-3252.bay.webtv.net> <1141907306.333725.215160@i40g2000cwc.googlegroups.com> <1210ser332cpg35@corp.supernews.com> <1141936980.983089.217740@v46g2000cwv.googlegroups.com> <1141944950.194014.62210@j33g2000cwa.googlegroups.com> <1141959810.308504.202590@u72g2000cwu.googlegroups.com> <847Qf.74776$PL5.71405@newssvr11.news.prodigy.com> <1141983043.843913.310960@u72g2000cwu.googlegroups.com> <1141999728.847290.48890@i40g2000cwc.googlegroups.com> Subject: Re: Current through coils Message-ID: Date: Fri, 10 Mar 2006 16:48:10 GMT wrote: > The fact you can't understand simple direct answers does the same. I love simple answers, Tom. What I don't like are simple-minded answers based on an invalid model. > When Roy measured current (and I did the same) using inductive coupling > in a current trasformer, a method that requires a time-varying current > to excite the secondary, you dismissed Roy's measurements with some odd > response about him measuring current that doesn't flow. The inductive coupling does NOT require a time-varying current. All it requires is a time-varying H-field. That standing wave H-field is indeed varying but it's not because current is moving laterally up or down the wire. That H-field is fixed at a point on the line exchanging energy with the E-field which is also fixed at the same point. If the H-field is not moving laterally up or down the wire (it isn't) then the current is NOT flowing. You must have missed that day in your fields and waves class. Take a metal rod. Slip a string through a washer and tie it. Loop the string onto the metal rod. Put a grommet on the rod on each side of the string to keep it in one place in the X dimension on the wire. Now, keeping the X dimension fixed, swing the loop in the plane of the Y and Z dimensions and look at it on edge. You are looking at a physical analogy of the standing wave current at a point on a wire. Is the string moving? Not in the X dimension which is constant and fixed by the grommets. At any point on a wire with standing waves, the E-field and H-field are not moving laterally up and down the wire. They are *stationary* at a point on the wire. All that is happening at that point is the E-field and H-field are swapping energy at the RF frequency. The current probe naturally picks up those stationary oscillating fields. You and Roy still don't understand what it was that was being measured.The current that you and Roy measured was not flowing. It was just standing there. That's why they call it a *standing* wave. The currents that are required to be constant through the coil are the traveling-wave currents. A standing wave is not at all a wave in the classic definition of EM waves. It is simply a superposition of two classic EM waves flowing in opposite directions. Here's an optical example of what is happening to you. The yellow light coming from your TV is an interference pattern between red, blue, and green light. You are measuring yellow light thinking that's a primary color. It is not. But you could use your yellow light measurement to estimate the strength of the primary colors. The standing-wave current is an interference pattern caused by superposition of forward and reflected current waves. Like the yellow light you are seeing, it is not primary, and like the yellow light, it is an artifact of interference.. In a wire in which one amp is flowing in one direction and one amp is flowing in the opposite direction, there is no net flow of current. Therefore, standing wave current has no net flow. That is obvious from its constant, fixed phase angle which doesn't change (much). > I already measured the phase of current, and it is nearly zero degrees. The measured phase of the net standing wave current is near zero degrees whether a coil exists or not. All it means is that the net standing wave current is standing still. Basing your conclusions upon measurements of a current that is not even flowing is foolish. > I don't know what others think, but it is starting to look to me like > you either don't understand the basics of measurements or you are just > unwilling to learn. You have been seduced by your model that is known to fail in the presence of standing waves. Why you cling to such a false prophet in the real world is beyond me. > I can measure that. My network analyzer measures time delays. The > problem I see is if I take time from my busy schedule and measure it, > you will either call me a liar or say I measured current that doesn't > flow. If you measure a traveling wave current, you will be measuring a current that is actually flowing. Your S12 phase shift measurement showed a -60 to -70 degree phase shift in a 100uH coil at one MHz. That measurement of yours has already proved that your lumped-circuit model is invalid. Why didn't you just use the zero degrees predicted by the lumped-circuit model instead of measuring it? :-) > Before measuring anything specific I'm going to warn you that I've > measured group delays many times before, and the group delay in an > inductor is significantly less than the group delay in a transmission > line of the same conductor length. I know that from past experience. I know that, Tom. The point is: If there is any appreciable delay through the coil, that fact violates the presuppositions of the lumped- circuit model. Therefore, a lumped-circuit model cannot be used to explain the characteristics of that real-world coil and especially not in a standing wave environment. > But if you promise to control yourself and not dismiss a measurement > with personal attacks or insults, and promise to not do an about-face > like you did with Roy and say "you really didn't measure current that > moves with your thing that only measures changing current", I will do > that. I appreciate that and I would also appreciate it if you didn't pencil whip the results before reporting them. Please just be honest. I assume we are both after the truth. And be sure to measure a coil something of the size of a 75m bugcatcher coil. I think a 75m bugcatcher coil would show more of a delay than a toroidal inductor of the same inductive reactance. > I really wish some of your ideas were correct. If they were correct, I > would not have thousands of feet of coaxial cables coiled under my > bench. I would not be forcing customers to cut long delay lines when > their equipment could just use a simple wound up piece of enameled > wire. Surely, you are familiar with helical transmision lines with a very, very small velocity factor. And Intel does use simple coils as delay lines in some of their PCB designs. > Does ANYONE on this newsgroup understand Cecil? I need help here. They are there, Tom. But they just don't want to tangle with a junk yard dog. Most people don't have a thick enough skin to withstand your onslaughts. I get a couple of emails a week from those guys. One distinguished gentleman and well known ham said that you have never lost an argument, even when you were wrong. I know exactly what he means. > What a silly statement. We are measuring a time-varying current that > doesn't flow or change! It's magnitude changes but it indeed doesn't flow or change phase. It's magnitude changes because the E-field and H-field are continuously exchanging energy at the frequency of operation. If you understood the implications of a constant, fixed, unchanging phase, you would know that. > Yes, if he wrote what you quoted and you didn't lift something out of > context I totally disagree with him. So be it. > > Your lumped-circuit model > > is known to fail in the presence of standing waves. > > Nonsense. YOUR LUMPED-CIRCUIT MODEL IS KNOWN TO FAIL IN THE PRESENCE OF STANDING WAVES! What is it about that statement that you don't understand? Your lumped-circuit model presupposes conditions that don't exist in a standing wave environment. Therefore, it is invalid and another more powerful model must be chosen.Because your chosen model is invalid, the validity of everything you say is questionable. The lumped-circuit model is a subset of the distributed-network model. The distributed-network model is a subset of Maxwell's equations. If you don't understand the limitations of the model, you will choose to use it under the wrong circumstances. That's what you, Roy, and others have done. -- 73, Cecil, W5DXP Article: 222052 of rec.radio.amateur.antenna From: "Cecil Moore" References: <1141929188.910581.171220@p10g2000cwp.googlegroups.com> <1211ig3hafcm451@corp.supernews.com> <1142003771.861185.56110@e56g2000cwe.googlegroups.com> Subject: Re: Current through coils Message-ID: Date: Fri, 10 Mar 2006 17:04:54 GMT wrote: > What Cecil needs to do is bias the coil with a DC bias current that > safely exceeds the peak RF current. > > Then he would have RF current flowing in only one direction. I should have said: have the RF current wave flowing only in the forward direction.Wes knew what I meant. -- 73, Cecil, W5DXP Article: 222053 of rec.radio.amateur.antenna From: "Cecil Moore" References: <1141864325.153022.145680@p10g2000cwp.googlegroups.com> <18782-440FBF35-53@storefull-3252.bay.webtv.net> <1141907306.333725.215160@i40g2000cwc.googlegroups.com> <1210ser332cpg35@corp.supernews.com> <1141936980.983089.217740@v46g2000cwv.googlegroups.com> <1141944950.194014.62210@j33g2000cwa.googlegroups.com> <1141959810.308504.202590@u72g2000cwu.googlegroups.com> <847Qf.74776$PL5.71405@newssvr11.news.prodigy.com> <1141983043.843913.310960@u72g2000cwu.googlegroups.com> <1141999728.847290.48890@i40g2000cwc.googlegroups.com> <1142012371.812551.124120@v46g2000cwv.googlegroups.com> Subject: Re: Current through coils Message-ID: <1ujQf.44208$F_3.30560@newssvr29.news.prodigy.net> Date: Fri, 10 Mar 2006 18:22:53 GMT wrote : > That is incorrect for the conditions we are outlining, and it is > misleading Cecil. It has him lost in a world of reflections. What is causing the misleading part is: THE LUMPED-CIRCUIT MODEL FAILS IN THE PRESENCE OF STANDING WAVES! > There is no virtually no difference in phase delay in current at each > end of a relatively compact inductor. Is a 75m bugcatcher coil a "relatively compact indictor"? If you say yes, you are stuck with its measured delay. If you say no, then we are not discussing the typical amateur radio mobile loading coil. Of course, one turn on a toroid is going to exhibit the characteristics you are presenting. But that is not a typical bugcatcher coil either. > The Tesla coil, by definition of how it works, violates all boundaries > of the examples myself and others are giving Cecil. It does not apply > to the discussion at all. False: A 75m bugcatcher coil used as a 1/4WL resonator on 9-10 MHz meets the minimum requirements for a Tesla coil. It uses 1/6 wavelength of wire on 75m. I'll bet it would certainly arc at a kilowatt. The typical minimum Tesla system is a coil with a top hat sphere. It looks a lot like your 160m mobile antenna. :-) > It is not operated at a fraction of > self-resonance as people SHOULD know a good mobile loading coil is. A 75m bugcatcher coil is operating close enough to its self-resonant frequency that the self-resonant effects are certainly present. A 75m bugcatcher coil can be considered to be a lumped circuit impedance at 60 Hz but certainly not at 4000000 Hz. In fact, that is the whole question. At what frequency can the lumped circuit model be validly used on a 75m bugcatcher coil? I'm willing to bet that frequency is lower than 1000000 Hz. > It has no bearing at all on the discussion, ... Wishful thinking on your part. . > In fact, a Tesla coil has more in common with a cavity resonator > than it does with a conventional inductor." A 75m bugcatcher coil has more in common with a cavity resonator than it does with your lumped circuit inductance. > "at its operating frequency, a Tesla coil is NOT a > lumped-element induction coil". Neither is a 75m bugcatcher coil. > Everyone in the conversation has been very careful to clearly establish > the boundary conditions that the behavior we are talking about is > significantly below self-resonance, an inductor of compact form factor, > and an inductor of good design. A 75m bugcatcher coil used on 4 MHz is NOT significantly below the self-resonant frequency of 9-10 MHz. THE LUMPED-CIRCUIT MODEL FAILS IN A STANDING WAVE ENVIRONMENT! In the face of that simple technical fact, all other discussion is moot. Anyone wishing to validly model a 75m bugcatcher coil used on a mobile antenna is forced to choose a model that does not presuppose faster than light wave travel through a 75m bugcatcher coil. It's as simple as that. Tom, with a straight face, I want you to assert that the RF waves on a 75m bugcatcher mobile antenna are traveling faster than the speed of light. If it takes 125 nanoseconds for the forward current wave to make it from the end of the antenna and back to the feedpoint, then the lumped-circuit model yields invalid results. TDR anyone? -- 73, Cecil, W5DXP Article: 222054 of rec.radio.amateur.antenna From: "Steve Nosko" Subject: Re: Dipole Extension Date: Fri, 10 Mar 2006 11:41:28 -0600 Message-ID: References: It's a shame Bill is gone. Not to worry. It should work just fine as-is. Mine resonates on 7.1 and works just fine on the whole band. However, if you insist...Nothing special about extending. Just about any wire will work. The most important things to use a mechanical technique suitable for the job and it won't hurt to use a wire of similar gauge. Insulation is irrelevant. Use the dipole formula 468/f(Mhz) to figure out the difference. Run the formula for the freq it is cut for, then for the freq you want and subtract (and divide by 2) to get the amount you need to add to each end. (or just use 234/f for the amount to add on each end). As a double check, with Excel I get 5.49295774647888 inches on each end... Cut very carefully! That's about 5 and 31.5492957746483 / 64ths inches. (:-) 73, Steve, K9DCI "Dick, AA5VU" wrote in message news:aa5vuNOSPAM-547450.06555410032006@newsclstr02.news.prodigy.com... > I have an old (but very good) W9INN 40/80 dipole. The only problem is > it is cut for the upper phone band (centered at ~7.200) for 40 meters > and I now do most operating in the lower portion of the band and would > like to move the center to about 7.100 MHz. The 40 meter portion of the > antenna is all soldered so I cannot just unwrap and extend it bit. > > Any suggestions on the best way to add a extension and how much to add? > > I have been thinking about cutting it and soldering in an X?-inch > splice. Does the extension wire have to really match? > > Dick AA5VU Article: 222055 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Current through coils References: <1211ig3hafcm451@corp.supernews.com> <1142003771.861185.56110@e56g2000cwe.googlegroups.com> Message-ID: Date: Fri, 10 Mar 2006 19:29:17 GMT Wes Stewart wrote: > "Cecil Moore" wrote: >> Wes knew what I meant. > > I did? Hopefully anyone with an IQ above 80 knew that. :-) -- 73, Cecil http://www.qsl.net/w5dxp Article: 222056 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Current through coils References: <1141864325.153022.145680@p10g2000cwp.googlegroups.com> <18782-440FBF35-53@storefull-3252.bay.webtv.net> <1141907306.333725.215160@i40g2000cwc.googlegroups.com> <1210ser332cpg35@corp.supernews.com> <1141936980.983089.217740@v46g2000cwv.googlegroups.com> <1141944950.194014.62210@j33g2000cwa.googlegroups.com> <1141959810.308504.202590@u72g2000cwu.googlegroups.com> <847Qf.74776$PL5.71405@newssvr11.news.prodigy.com> <1141983043.843913.310960@u72g2000cwu.googlegroups.com> <1141999728.847290.48890@i40g2000cwc.googlegroups.com> <1142012371.812551.124120@v46g2000cwv.googlegroups.com> Message-ID: Date: Fri, 10 Mar 2006 19:37:45 GMT John Popelish wrote: > Any discussion of inductors and waves needs to either > select an example inductor for discussion, e.g., 75m bugcatcher mobile loading coil. > or remain general enough to > cover anything that might be called an inductor. e.g., Maxwell's equations. Certainly not a lumped-circuit model that presupposes that EM waves travel through anything and everything faster than the speed of light. > Or else, endless and pointless arguments will ensue. Yep, notice how the inductors that Tom is talking keep getting smaller and smaller with time. Pretty soon they will indeed be point-sized inductors. :-) -- 73, Cecil http://www.qsl.net/w5dxp Article: 222057 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Current through coils References: <1141907306.333725.215160@i40g2000cwc.googlegroups.com> <1210ser332cpg35@corp.supernews.com> <1141936980.983089.217740@v46g2000cwv.googlegroups.com> <1141944950.194014.62210@j33g2000cwa.googlegroups.com> <1141959810.308504.202590@u72g2000cwu.googlegroups.com> <847Qf.74776$PL5.71405@newssvr11.news.prodigy.com> <1141983043.843913.310960@u72g2000cwu.googlegroups.com> <1141999728.847290.48890@i40g2000cwc.googlegroups.com> <1142012371.812551.124120@v46g2000cwv.googlegroups.com> <1ujQf.44208$F_3.30560@newssvr29.news.prodigy.net> <1142017244.466593.309060@i40g2000cwc.googlegroups.com> Message-ID: <57lQf.55569$Jd.21377@newssvr25.news.prodigy.net> Date: Fri, 10 Mar 2006 20:14:57 GMT w8ji@akorn.net wrote: > Cecil Moore wrote: >>A 75m bugcatcher coil used on 4 MHz is NOT significantly below >>the self-resonant frequency of 9-10 MHz. > > Yes it is, but not so far as to have perfectly equal currents at each > end an zero phase shift in current. It is in the neither land between a > Tesla coil (which is still nothing like my mobile antenna, but at least > getting closer) and a idealized lumped component. That's about a 99% change in attitude from when we started this discussion a couple of years ago. At that time you were claiming that a 75m bugcatcher coil modeled as a lumped inductance with EZNEC showed zero change in current magnitude and phase and that was that. I'm glad to see the truth winning for a change. I think you are going to have to go a *LOT* lower in frequency than 4000000 Hz before a 75m bugcatcher coil can be treated as a lumped-inductance. >>THE LUMPED-CIRCUIT MODEL FAILS IN A STANDING >>WAVE ENVIRONMENT! In the face of that simple technical fact, >>all other discussion is moot. Anyone wishing to validly model a >>75m bugcatcher coil used on a mobile antenna is forced to choose >>a model that does not presuppose faster than light wave travel >>through a 75m bugcatcher coil. It's as simple as that. > > Nonsense. You are ignoring the coupling mechanisim inside the inductor. That coupling mechanism works, at best, a lot lower than the speed of light and only on the voltage. In a high-Q inductor, the current is known to lag the voltage by a phase angle approaching 90 degrees. Do you have any idea what the velocity factor of a 75m bugcatcher coil is? I'll bet Reg can tell us. If the voltage is indeed traveling at the speed of light, the current is known to lag the voltage by a large number of degrees approaching 90 degrees for an ideal coil. The laws of physics strikes again. How can you bring yourself to ignore them? The voltage cannot travel faster than the speed of light and the current is lagging by, e.g. 60 degrees. It's hard not to suffer a 40 nS current wave delay through the coil on 4 MHz. I've told this to you before but you have avoided the subject like a plague. > What you (and the one or two others who seem to agree with you) > repeatedly ignore or forget is magnetic flux couples one turn to > another. A real inductor is always someplace between the two extremes > of something like a radial mode helice (helically loaded whip) and an > ideal lumped component. You are talking about the E-field, not the H-field. I can agree with the E-field propagating at the speed of light but the H-field is known to lag the E-field by an angle approaching 90 degrees in the limit for an ideal inductor. Or is that another law of physics that you simply choose to ignore? > Everyone is freely admitting there is *some* transmission line effect > going on. There is some distrbuted component (a series of inductors > shunted by capacitors) going on. Are you admitting that a 75m bugcatcher coil can be modeled as a transmission line with a Z0 and a VF? If so, you are giving up on your lumped-constant model. Actually, since the lumped-constant model is a subset of the distributed-network model, the lumped- constant model is very often wrong when the distributed-network model is correct. OTOH, it is impossible for the lumped-constant analysis to be right while the distributed-network analysis is wrong. So much for your choice of models. > Everyone (except you) is being careful to qualify remarks by specifying > the inductor is operating well below self-resonance. A 75m bugcatcher coil is NOT operating "well below" self-resonance. It is operating at 1/2 the self-resonant frequency. If one adds one foot at a time to the stinger above a 75m bugcatcher coil, at exactly what frequency does it cease to act like a "velocity inhibited slow-wave helical" and start acting like a lumped inductance? I propose that frequency is considerably lower than 1000000 Hz. > If you weren't so pig-headed you could look at the measured data at: > http://www.w8ji.com/mobile_antenna_current_measurements_at_w8ji.htm You measured standing wave current, Tom. Your measurements are meaningless! Standing wave current has the same constant phase whether the coil exists or not. Your measurements prove absolutely nothing that is not already known. -- 73, Cecil http://www.qsl.net/w5dxp Article: 222058 of rec.radio.amateur.antenna From: "Dick, AA5VU" Subject: Re: Dipole Extension References: Message-ID: Date: Fri, 10 Mar 2006 20:24:41 GMT In article , John Ferrell wrote: > The 1/2 wave difference on 40M of 7.2 and 7.1mhz is only about a foot. > The change in a DIPOLE at 40M would be difficult to measure. > > I would not change it. > Do you have an indication that it needs adjustment? John, When i trimmed it the first time (years ago) I was working mostly SSB so it is great in phone band and okay in the old Novice portion. I am now working mostly 40 meter RTTY and PSK and these are at 7.070 and 7.035. The current antenna shows SWR of about 1:8 at 7.100 and goes up to 2:0 at 7.050. My TS-570S tuner makes the rig smile but I feel it would be better if I could extend it a bit. The problem is there is no wrapped back wire that I could let out and hate to use a jumper extender at the loading coil. I may have to just bit the bullet and cut some wire per the formulas by Steve, K9DCI, and solder it in the middle some place. Still thinking about it. The WX in South Texas is too nice for antenna work. I will probably put it off until the WX is bad. 73, Dick AA5VU Article: 222059 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Dipole Extension References: Message-ID: Date: Fri, 10 Mar 2006 20:39:17 GMT Dick, AA5VU wrote: > The current antenna shows SWR of about 1:8 at 7.100 and goes up to > 2:0 at 7.050. My TS-570S tuner makes the rig smile but I feel it would > be better if I could extend it a bit. If you enjoy lowering your SWR below 2:1, go for it. If you think it will help the ham on the other end copy you better, you are, as someone has said before, picking fly spots out of black pepper. -- 73, Cecil http://www.qsl.net/w5dxp Article: 222060 of rec.radio.amateur.antenna From: "Dale Parfitt" References: Subject: Re: Dipole Extension Message-ID: Date: Fri, 10 Mar 2006 21:25:07 GMT "Dick, AA5VU" wrote in message news:aa5vuNOSPAM-4A4374.14244010032006@newsclstr02.news.prodigy.com... > In article , > John Ferrell wrote: > >> The 1/2 wave difference on 40M of 7.2 and 7.1mhz is only about a foot. >> The change in a DIPOLE at 40M would be difficult to measure. >> >> I would not change it. >> Do you have an indication that it needs adjustment? > > John, > > When i trimmed it the first time (years ago) I was working mostly SSB so > it is great in phone band and okay in the old Novice portion. I am now > working mostly 40 meter RTTY and PSK and these are at 7.070 and 7.035. > > The current antenna shows SWR of about 1:8 at 7.100 and goes up to > 2:0 at 7.050. My TS-570S tuner makes the rig smile but I feel it would > be better if I could extend it a bit. > > The problem is there is no wrapped back wire that I could let out and > hate to use a jumper extender at the loading coil. > > I may have to just bit the bullet and cut some wire per the formulas by > Steve, K9DCI, and solder it in the middle some place. > > Still thinking about it. The WX in South Texas is too nice for antenna > work. I will probably put it off until the WX is bad. > > 73, Dick AA5VU I am not familair with this antenna, but if it has a choke/trap for 40M, just add a foot of wire on the side of the choke/trap that is closest to the center insulator- let it hang down and dangle. You can clip it on as one poster said- this is a high Z point and contact resistance is a non-issue. But as others have said, the on-air difference is zero. Dale W4OP Article: 222061 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Current through coils References: <1210ser332cpg35@corp.supernews.com> <1141936980.983089.217740@v46g2000cwv.googlegroups.com> <1141944950.194014.62210@j33g2000cwa.googlegroups.com> <1141959810.308504.202590@u72g2000cwu.googlegroups.com> <847Qf.74776$PL5.71405@newssvr11.news.prodigy.com> <1141983043.843913.310960@u72g2000cwu.googlegroups.com> <1141999728.847290.48890@i40g2000cwc.googlegroups.com> <1142012371.812551.124120@v46g2000cwv.googlegroups.com> <1ujQf.44208$F_3.30560@newssvr29.news.prodigy.net> <1142017244.466593.309060@i40g2000cwc.googlegroups.com> <57lQf.55569$Jd.21377@newssvr25.news.prodigy.net> <1142026591.641276.21100@p10g2000cwp.googlegroups.com> Message-ID: Date: Fri, 10 Mar 2006 22:11:37 GMT w8ji@akorn.net wrote: > Please tell us all how you would measure the "traveling current" while > ignoring "standing wave current". Good question. One would ideally do it in a system without reflections. I am struggling with that concept right now. The best thought I have come up with so far is simple: coil +----////----+ | | source --- cap | --- | | +--/\/\/\/\--+ resistor I'm not a measurements guy so I could use some help. What's wrong with just reporting the measured the delay through your test coils? Your measured data already shows the current on one side of the coil to be different from the current on the other side of the coil. All we have to worry about now is the delay through the coils. If I've got your attention, let me repeat something I posted days ago. The forward current through the coil can indeed be assumed to be equal magnitude at both ends of the coil without much error. That should make you happy. The delay through the coil is whatever it is but it is nowhere near zero. I assume that makes you unhappy. The reflected current through the coil can indeed be assumed to be equal magnitude at both ends of the coil without much error. That should make you happy. The delay through the coil is whatever it is but it is nowhere near zero. I assume that makes you unhappy. The standing wave is the phasor sum of the forward wave and reflected wave. Its magnitude can vary from about double the forward current at a current loop to close to zero at a current node. I assume that makes you unhappy. The standing wave phase is close to constant and fixed near zero degrees within 1/4WL of the feedpoint. I assume that makes you happy. So three out of six results should make you happy and that's about all any mere mortal can hope for. :-) -- 73, Cecil http://www.qsl.net/w5dxp Article: 222062 of rec.radio.amateur.antenna From: "Ed Laughery" Subject: ScrewDriver Antenna Article in February Antennex issue Message-ID: Date: Fri, 10 Mar 2006 16:18:17 -0600 Hi I would appreciate a review of the ScrewDriver antenna article in the February 2006 issue of Antennex. 1. Is it a full construction article? 2. If #1 is true, can the antenna as described be built from easily obtainable components and buit with a resonable toolset? 3. any other comments you would care to share Thanks in advance to all for their consideration. 73 de Ed AD5JV Article: 222063 of rec.radio.amateur.antenna From: Gene Fuller Subject: Re: Current through coils References: <1141929188.910581.171220@p10g2000cwp.googlegroups.com> <1211ig3hafcm451@corp.supernews.com> <1142003771.861185.56110@e56g2000cwe.googlegroups.com> Message-ID: Date: Sat, 11 Mar 2006 00:54:07 GMT Cecil Moore wrote: > John Popelish wrote: > >> When you talk about current flowing, you seem to be thinking of >> current waves traveling along a conductor. Others seem to be saying >> "current" and thinking of charge movement. I think that only the >> second is technically correct ... > > > John, many thanks for some rationality from a cool head. > > Conventions aside, that sounds about right. So would you agree > that if there's a forward current of one amp and a reflected > current of one amp, the net charge movement is zero and therefore > the standing wave current is not "going" anywhere? How can something > with a constant fixed phase angle of zero degrees "go" anywhere? > >> Standing waves involve no net wave travel in either direction, though >> anywhere except at the current nodes, charge is certainly moving back >> and forth along the conductor, during a cycle. > > > That's unclear to me. Why can't the E-field and H-field simply be > exchanging energy at a point rather than any net charge moving > laterally? Cecil, I think I said all of that before the fun and games started. In any case I agree 100% with John. Let me try again to answer your question. This is all very basic textbook stuff. I claim not the slightest bit of credit for any of this. First, I hope we can agree that current is defined as the movement of charge. In this case the charge moves only in the direction of the wire, let's call it the z-direction. The generic equation for a forward traveling wave is simply: y = A cos (kz-wt) The generic equation for a reverse traveling wave is: y = B cos (kz+wt) One can add constant phase offsets to the cosine arguments, but it does not make any difference here. It just makes things look messy, especially in ASCII. The parameters k and w are not independent either, but again that does not really matter here. In the case of current we can say: If = Io cos (kz-wt) Ir = Io cos (kz+wt) I have set the "A" and "B" coefficients to the same value, Io, for simplicity. If the currents are not the same the math gets a little messier, but there is no fundamental difference. Keep in mind that the If and Ir refer to the current that moves along the z-direction, i.e., charge moving in the back-and-forth direction along the wire. The "f" refers to the forward "wave", and the "r" refers to the reverse "wave". The current in both cases is not "forward" or "reverse" but simply back-and-forth as in any AC condition. It is essential to separate the concepts of wave and current. They may be connected, but they are not the same, and they are not interchangeable. OK, now lets add these two traveling waves together to make a standing wave. This is a linear system, and superposition applies. We can simply add the components. The basic equation is: Isw = If + Ir = Io { cos (kz-wt) + cos (kz+wt) } Through the use of a standard trigonometric identity this can be reduced to: Isw = 2Io cos (kz) cos (wt) What can be seen immediately is that the standing wave current still has exactly the same time dependence that the traveling waves had. The magnitude of the current is now a function of z, unlike the constant magnitude in the traveling waves. The "current" is still defined as above, namely the charge that moves back-and-forth in the z-direction. The current oscillation factor (wt) is now decoupled from "z", unlike the traveling wave case. The "wave" is stationary. The current itself, however, behaves exactly the same as in the case of the traveling waves. Of course there are important differences in radiation patterns for traveling waves and standing waves. The magnitude of the current is different along the wire. However, except at the standing wave nodes, the standing wave current is very real and non-zero. I am almost embarrassed to write this, since surely you and most readers know all of this quite thoroughly. However, it appears you may have overlooked something. I hope this helps. 73, Gene W4SZ Article: 222064 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Current through coils References: <1141929188.910581.171220@p10g2000cwp.googlegroups.com> <1211ig3hafcm451@corp.supernews.com> <1142003771.861185.56110@e56g2000cwe.googlegroups.com> Message-ID: Date: Sat, 11 Mar 2006 03:16:26 GMT Gene Fuller wrote: > Isw = 2Io cos (kz) cos (wt) > > What can be seen immediately is that the standing wave current still has > exactly the same time dependence that the traveling waves had. The > magnitude of the current is now a function of z, unlike the constant > magnitude in the traveling waves. The "current" is still defined as > above, namely the charge that moves back-and-forth in the z-direction. On the contrary, when kz is not linked by a plus or minus sign to wt, the wave doesn't move anymore. Maybe you need a review? Gene, you are a genius. Why didn't I think of that? I recognize that equation from "Optics", by Hecht. Pick any point, 'z', and see what you get. Hecht says, "It doesn't rotate at all, and the resultant wave it represents *DOESN'T PROGRESS THROUGH SPACE* - it's a standing wave." The RF equivalent of a standing wave of light that doesn't progress through space is an RF standing wave that doesn't progress through a wire. That's what I have been telling you guys. Standing waves don't move. Standing wave current doesn't flow! Even in empty space, a light standing wave doesn't progress through space, i.e. IT DOESN'T MOVE! That is on page 289 of "Optics", by Hecht, 4th edition. From "Fields and Waves ...", by Ramo & Whinnery, in describing the standing wave situation: "The total energy in any length of line a multiple of a quarter wavelength long is constant, *merely interchanging between energy in the electric field of the voltages and energy in the magnetic field of the currents*." Again, proof that standing wave energy doesn't flow. It just stands there being exchanged between the E-fields and the H-fields. That is from page 40 of "Fields and Waves in Communications Electronics", by Ramo, Whinnery, and Van Duzer. Now I did make a mistake in what I said earlier and I apologize for that. I said the energy in the E-field and H-field exchanges at a "point" on the line. Obviously, since a current maximum occurs at a voltage zero, that can't be true so I mis-spoke. Since the voltage maximum is 1/4 wavelength away from the current maximum, as Ramo & Whinnery say, one has to consider 1/4WL of line, and not a point as I said. Consider a 1/4WL section of line with a voltage maximum at Z and a current maximum at Z+(1/4WL). The current at Z is zero and the voltage at Z+(1/4WL) is zero. The net energy in that 1/4WL of line is constant. No net energy is flowing into or out of that 1/4WL of line. At some point the E-field energy is strongest toward the Z end and 1/4 cycle later, it is strongest toward the Z+(1/4WL) end. Since there is no net energy flow into or out of the line, there is no net current flow into or out of the line. > The current oscillation factor (wt) is now decoupled from "z", unlike > the traveling wave case. The "wave" is stationary. The current itself, > however, behaves exactly the same as in the case of the traveling waves. Sorry, you are wrong there, Gene. On that same page, Hecht says, "The standing wave does not move through space: it is clearly not of the form f(x +/- vt). For your equations that statement would be: The standing wave current does not move through the wire: it is clearly not of the form f(z +/- wt). When you separate the 'z' function from the 'wt' function, the wave doesn't move anymore. It, well, it just stands there, like a good little standing wave. > Of course there are important differences in radiation patterns for > traveling waves and standing waves. The magnitude of the current is > different along the wire. However, except at the standing wave nodes, > the standing wave current is very real and non-zero. And stationary as Hecht says. Your own equation indicates that it is stationary, i.e. not moving. > I am almost embarrassed to write this, ... As you should be for not realizing that [Isw = 2Io cos (kz) cos (wt)] is "clearly not of the form f(z +/- wt)", i.e. of the form of a current traveling wave that moves. Time to refresh you memory on that subject. -- 73, Cecil http://www.qsl.net/w5dxp Article: 222065 of rec.radio.amateur.antenna From: Gene Fuller Subject: Re: Current through coils References: <1141929188.910581.171220@p10g2000cwp.googlegroups.com> <1211ig3hafcm451@corp.supernews.com> <1142003771.861185.56110@e56g2000cwe.googlegroups.com> Message-ID: <%yrQf.8704$8w2.3002@bgtnsc04-news.ops.worldnet.att.net> Date: Sat, 11 Mar 2006 03:34:19 GMT Cecil, Good grief!!!! I said several times that the standing wave does not move. I also said the "wave" is not the same thing as the "current". The current is nonzero even though the wave is stationary. At this point it is obvious that you are just interested in causing a fuss, and not the slightest bit interested in reaching any sort of resolution of this item. Bye. 73, Gene W4SZ Cecil Moore wrote: > Gene Fuller wrote: > >> Isw = 2Io cos (kz) cos (wt) >> >> What can be seen immediately is that the standing wave current still >> has exactly the same time dependence that the traveling waves had. The >> magnitude of the current is now a function of z, unlike the constant >> magnitude in the traveling waves. The "current" is still defined as >> above, namely the charge that moves back-and-forth in the z-direction. > > > On the contrary, when kz is not linked by a plus or minus sign > to wt, the wave doesn't move anymore. Maybe you need a review? > > Gene, you are a genius. Why didn't I think of that? I recognize > that equation from "Optics", by Hecht. Pick any point, 'z', and > see what you get. Hecht says, "It doesn't rotate at all, and the > resultant wave it represents *DOESN'T PROGRESS THROUGH SPACE* - it's > a standing wave." The RF equivalent of a standing wave of light that > doesn't progress through space is an RF standing wave that doesn't > progress through a wire. That's what I have been telling you guys. > Standing waves don't move. Standing wave current doesn't flow! > Even in empty space, a light standing wave doesn't progress > through space, i.e. IT DOESN'T MOVE! > That is on page 289 of "Optics", by Hecht, 4th edition. > > From "Fields and Waves ...", by Ramo & Whinnery, in describing the > standing wave situation: "The total energy in any length of line > a multiple of a quarter wavelength long is constant, *merely > interchanging between energy in the electric field of the voltages > and energy in the magnetic field of the currents*." Again, proof > that standing wave energy doesn't flow. It just stands there > being exchanged between the E-fields and the H-fields. > That is from page 40 of "Fields and Waves in Communications > Electronics", by Ramo, Whinnery, and Van Duzer. > > Now I did make a mistake in what I said earlier and I apologize for > that. I said the energy in the E-field and H-field exchanges at a > "point" on the line. Obviously, since a current maximum occurs at > a voltage zero, that can't be true so I mis-spoke. Since the voltage > maximum is 1/4 wavelength away from the current maximum, as Ramo & > Whinnery say, one has to consider 1/4WL of line, and not a point as > I said. > > Consider a 1/4WL section of line with a voltage maximum at Z and > a current maximum at Z+(1/4WL). The current at Z is zero and the > voltage at Z+(1/4WL) is zero. The net energy in that 1/4WL of line > is constant. No net energy is flowing into or out of that 1/4WL > of line. At some point the E-field energy is strongest toward > the Z end and 1/4 cycle later, it is strongest toward the Z+(1/4WL) > end. Since there is no net energy flow into or out of the line, > there is no net current flow into or out of the line. > >> The current oscillation factor (wt) is now decoupled from "z", unlike >> the traveling wave case. The "wave" is stationary. The current itself, >> however, behaves exactly the same as in the case of the traveling waves. > > > Sorry, you are wrong there, Gene. On that same page, Hecht says, "The > standing wave does not move through space: it is clearly not of the > form f(x +/- vt). For your equations that statement would be: The > standing wave current does not move through the wire: it is clearly > not of the form f(z +/- wt). When you separate the 'z' function from > the 'wt' function, the wave doesn't move anymore. It, well, it just > stands there, like a good little standing wave. > >> Of course there are important differences in radiation patterns for >> traveling waves and standing waves. The magnitude of the current is >> different along the wire. However, except at the standing wave nodes, >> the standing wave current is very real and non-zero. > > > And stationary as Hecht says. Your own equation indicates that it > is stationary, i.e. not moving. > >> I am almost embarrassed to write this, ... > > > As you should be for not realizing that [Isw = 2Io cos (kz) cos (wt)] > is "clearly not of the form f(z +/- wt)", i.e. of the form of a current > traveling wave that moves. Time to refresh you memory on that subject. Article: 222066 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Current through coils References: <1141929188.910581.171220@p10g2000cwp.googlegroups.com> <1211ig3hafcm451@corp.supernews.com> <1142003771.861185.56110@e56g2000cwe.googlegroups.com> Message-ID: Date: Sat, 11 Mar 2006 03:34:10 GMT John Popelish wrote: >> the net charge movement is zero and therefore >> the standing wave current is not "going" anywhere? > > Sorry, no. Gene just posted the equation for standing wave current. Isw = 2Io cos (kz) cos (wt) This is definitely not in the form of a traveling wave. Hecht, in "Optics" says the standing wave does not move through space. Presumably, for the same reason, a standing wave does not move through a wire. > Looking > just at just current, and at only a single point, a traveling current > wave and a standing current wave are indistinguishable. True but if you know the equation above, then they are distinguishable. > The only way to understand a standing wave having a phase of zero > degrees, that makes sense to me, is that it applies to all points > between one current node and the next. Yes, the subject in context is 1/4WL monopoles or 1/2WL dipoles. >> That's unclear to me. Why can't the E-field and H-field simply be >> exchanging energy at a point rather than any net charge moving >> laterally? > > In an isolated EM plane wave, I think this is the case, and displacement > charge in space takes the place of conductor current. But when a wave is > guided by a conductor, we can measure the charge sloshing back and forth > in the conductor in response to those fields. Yes, I was confused about that. If the question is changed to: "Why can't the E-field and H-field simply be exchanging energy within each 1/4WL rather than any net charge moving out of that 1/4WL?", it would make sense. Thanks John, for the refresher course. -- 73, Cecil http://www.qsl.net/w5dxp Article: 222067 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Current through coils References: <1141929188.910581.171220@p10g2000cwp.googlegroups.com> <1211ig3hafcm451@corp.supernews.com> <1142003771.861185.56110@e56g2000cwe.googlegroups.com> <1142040868.926875.4670@j33g2000cwa.googlegroups.com> Message-ID: Date: Sat, 11 Mar 2006 04:02:22 GMT w8ji@akorn.net wrote: > I have a 100 turn 2" diameter #18 gauge wire air core inductor. There > are 100 turns, so there is about 630 inches or 32 feet of wire in the > coil. > > I have a Network Analyzer with port to port time delay measurement > capability. It measures coaxial cables very well, and even clip leads. > > Cecil, please predict or guess the group delay of this inductor at 3.8 > MHz. Tell us all what that group delay means for your wave theory. Tom, I have no idea since you chose not to post the length of the coil or the inductance of the coil or the Q of the coil or even the turns/inch of the coil. Is your Network Analyzer equipped with current probes? If not, you are wasting your time. -- 73, Cecil http://www.qsl.net/w5dxp Article: 222068 of rec.radio.amateur.antenna From: richardharrison@webtv.net (Richard Harrison) Subject: Re: Current through coils Date: Fri, 10 Mar 2006 22:27:08 -0600 Message-ID: <28826-4412519C-544@storefull-3255.bay.webtv.net> References: <1142043207.752336.206250@j52g2000cwj.googlegroups.com> Cecil warned me that if I posted, the posting would be nit picked to pieces. I`ve read correct postings describing the incident and reflected waves on a transmission line, and Maxwell`s secret of radiation (displacement current produces a magnetic field same as conduction current). All this may be relevant or not to some extent, but they don`t seem to resolve the current through a coil. Tom, W8JI wrote: "You have consistently disagreed with me when I said the time delay through an inductor with tight mutual coupling from turn to turn is somewhat close to light speed over the physical length of the inductor, rather than the time it rakes to wind its way around the copper." That contradicts established experience. The property of reactance is to limit current flow. Inductive reactance limits by means of counter-emf which depends upon the rate at which current is changing in the coil. A-C current changes most rapidly at zero time (the axis crossings of the sine waveform). Lenz`s law says the counter-emf must oppose the growth of current in this case. Opposotion of the counter-emf causes the current to reach its maximum 1/4-cycle after the emf applied to the coil reaches its maximum. As almost everyone knows, the current lags by 90-degrees in a pure inductor. Make the turns coupling as tight as you can, the current is still delayed by 90-degrees. Now, it surely is possible to bypass a perfect inductor with a capacitor to mitigate a delay. I can`t repeat without retyping text on my screen, so the fact that I don`t retype everything only means I`m lazy. Right or wrong, W8JI may never lose an argument, but when he is clearly wrong it should be pointed out. Best regards, Richard Harrison, KB5WZI Article: 222069 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Current through coils References: <1141929188.910581.171220@p10g2000cwp.googlegroups.com> <1211ig3hafcm451@corp.supernews.com> <1142003771.861185.56110@e56g2000cwe.googlegroups.com> <1142043207.752336.206250@j52g2000cwj.googlegroups.com> Message-ID: <%qsQf.49691$H71.30038@newssvr13.news.prodigy.com> Date: Sat, 11 Mar 2006 04:34:03 GMT w8ji@akorn.net wrote: > Cecil, > You have consistently disagreed with me when I said time delay through > an inductor with tight mutual coupling from turn-to-turn is somewhat > close to light speed over the physical length of the inductor, No, I haven't, Tom. What you are describing is the voltage delay. I have never argued with you about the voltage delay through a coil. It occurs at the speed of light adjusted for VF. In EE101 everybody learns that the voltage leads the current through a coil. The question is by how much in a 75m bugcatcher coil? Have you ever seen a graph of the voltage vs current at the output of a series coil? It shows the current lagging the voltage by 90 degrees. It takes a series resonant capacitor to align the current with the voltage again. > rather > than the time it takes current to wind its way around through the > copper. If you can find a posting of mine like that, I'll give you $100. If you can't find it, please admit you are fibbing again about what I have said. > You didn't like my measurement of a small 100uH choke, I didn't say I didn't like it. You posted some results and then described those same results differently as time passed. At the moment, I have no idea what those results were. Was the -60 to -70 degree delay a voltage delay or a current delay? > and said > a large inductor like a bug catcher coil is different. You predicted > standing waves in that inductor. Now we are getting to the truth. A 75m bugcatcher is closer to being a Tesla coil than it is to being a lumped-inductor. It satisfies R.W.P. King's advice that if the wire length used to make the coil exceeds 1/6 wavelength then, "an adequate representation of the reactance of a coil with a nonuniformly distributed current is NOT POSSIBLE in terms of a coil with a uniform current". The 75m bugcatcher uses very close to 1/6 wavelength of wire. And yes, standing wave antennas have standing waves so a 75m bugcatcher coil is emersed in a standing wave environment. Quoting Dr. Corum: "Lumped element representations for coils REQUIRE that the current is uniformly distributed along the coil - no wave interference and no standing waves can be present on lumped elements." > I have a 100 turn 2 inch diameter air wound inductor of pretty good > quality. It is 10 inches long. What is the inductance? What is the Q? > Please tell all of us the time delay you expect in that inductor on 3.8 > MHz. Please tell all of us what that delay means for your various > changing theories about waves standing in that coil. First please describe the circuit used to drive the coil, what other components are in the loop, and how you are picking off the two currents at the ends of the coil. Is your Network Analyzer equipped with current probes? If not, you are wasting your time. We already know the delay for the voltage will approximate the speed of light adjusted for VF. -- 73, Cecil http://www.qsl.net/w5dxp Article: 222070 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Current through coils References: <1141929188.910581.171220@p10g2000cwp.googlegroups.com> <1211ig3hafcm451@corp.supernews.com> <1142003771.861185.56110@e56g2000cwe.googlegroups.com> <%yrQf.8704$8w2.3002@bgtnsc04-news.ops.worldnet.att.net> Message-ID: Date: Sat, 11 Mar 2006 04:37:45 GMT Gene Fuller wrote: > Good grief!!!! Good grief!!! I've already posted in another posting that I was mistaken about that. There is standing wave charge migrating from end to end in a 1/4WL monopole. Next time I have spaghetti, I'll give myself 20 licks with a wet noodle. -- 73, Cecil http://www.qsl.net/w5dxp Article: 222071 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Current through coils References: <1142043207.752336.206250@j52g2000cwj.googlegroups.com> <28826-4412519C-544@storefull-3255.bay.webtv.net> Message-ID: Date: Sat, 11 Mar 2006 04:52:48 GMT Richard Harrison wrote: > Tom, W8JI wrote: > "You have consistently disagreed with me when I said the time delay > through an inductor with tight mutual coupling from turn to turn is > somewhat close to light speed over the physical length of the inductor, > rather than the time it rakes to wind its way around the copper." > > That contradicts established experience. Tom seems to be confusing the effects of the E-field with the effects of the H-field. The E-field propagates at the speed of light through a coil. The H-field propagates at the speed of light through a capacitor. > Make > the turns coupling as tight as you can, the current is still delayed by > 90-degrees. Can the actual current phase delay be estimated knowing the Q of the coil? I don't recall a formula for that. > Now, it surely is possible to bypass a perfect inductor with a capacitor > to mitigate a delay. Dang Richard, now you've told Tom how to run his experiment in order to obtain the results he predicts. :-) -- 73, Cecil http://www.qsl.net/w5dxp Article: 222073 of rec.radio.amateur.antenna Subject: Re: Q. about height of the ends of a doublet From: Dave Oldridge References: Message-ID: Date: Sat, 11 Mar 2006 08:02:08 GMT rocky wrote in news:mar.sv-A1022D.17240808032006@news-rdr-02.rdc-kc.rr.com: > In article , > Dave Oldridge wrote: > >> Big Endian wrote in >> news:nospam-3801D8.18373207032006@news-rdr-02.rdc-kc.rr.com: >> >> > >> > My center of a 3.8 Mhz doublet is at about 35 feet and am going to >> > drop the ends from 30 feet to about 10 to 15 feet. Just wondering >> > if it will make all that much difference if any? >> >> There will be a marked improvement in the low angle performance in >> the direction off the ends of the antenna (the flattop is very poor >> at this). This will come at the expense of a sight loss (about .8db) >> off the pattern's top (where you can most afford it). You will also >> experience a slight deterioration in the SWR (based on 50 ohm coax) >> from about 1.34 to 2.05, easily managed by any tuner, including those >> built into many radios. You will also find that you need to shorten >> the antenna very slightly to maintain the same resonant frequency. >> >> This won't make it into a superior DX antenna but it may allow you to >> hear things you missed before. Basically, Bob Heinlein was right. >> There ain't any such thing as a free lunch. > > What I've read is that when the ends are dropped to an inverted Vee > configuration the feedpoint impedance drops closer to 50 ohms, but the > Vee bandwidth is more restricted. Hard to believe that lowering the > ends by 15 feet from 30 would make all that much difference on 75 > meters. It's only really noticeable on low-angle (about 30 degrees or so) signals >from the direction off the ends. -- Dave Oldridge+ ICQ 1800667 Article: 222074 of rec.radio.amateur.antenna From: "Dick, AA5VU" Subject: Re: Dipole Extension References: Message-ID: Date: Sat, 11 Mar 2006 10:24:13 GMT In article , "Dale Parfitt" wrote: > I am not familair with this antenna, but if it has a choke/trap for 40M, > just add a foot of wire on the side of the choke/trap that is closest to the > center insulator- let it hang down and dangle. You can clip it on as one > poster said- this is a high Z point and contact resistance is a non-issue. > But as others have said, the on-air difference is zero. > > Dale W4OP Late yesterday afternoon I decided to try the two alligator clips and some wire to run a test to see what would happen. Sounds easy but I made it very hard. To make a long shaggy-dog story short I added the wire and the SWR went out of sight. It acted like a dead short. I then lowered he antenna and cut the wire in half and it was still terrible. I then trashed he alligator clips and wire to and it was still terrible. After two hours of screwing around, I found some dummy (me) had the coax switch on the old Ringo Ranger rather than the W9INN antenna. By this time it was too dark to mess with anything. Going to start over when the sun comes up but this time I plan to ditch the alligator clips and attach a one foot wire using the connection nuts on the coil/trap or whatever w9inn used to call that thing between the 40 and 80 wires and will have the coax switch on the right antenna this time. Dick AA5VU (red-faced) Article: 222075 of rec.radio.amateur.antenna From: aRKay Subject: Re: Dipole Extension References: Message-ID: Date: Sat, 11 Mar 2006 10:31:09 GMT In article , Cecil Moore wrote: > Dick, AA5VU wrote: > > The current antenna shows SWR of about 1:8 at 7.100 and goes up to > > 2:0 at 7.050. My TS-570S tuner makes the rig smile but I feel it would > > be better if I could extend it a bit. > > If you enjoy lowering your SWR below 2:1, go for it. If you > think it will help the ham on the other end copy you better, > you are, as someone has said before, picking fly spots out > of black pepper. Cecil, You are correct but many of us tend to get obsessive about SWR. The enemy of good is better and many of us have wasted hours trying to make a good antenna better. It is part of being a ham. Dick AA5VU Article: 222076 of rec.radio.amateur.antenna From: Roy Lewallen Subject: Re: Current through coils Date: Sat, 11 Mar 2006 02:56:22 -0800 Message-ID: <1215b6onoaoke41@corp.supernews.com> References: <1142043207.752336.206250@j52g2000cwj.googlegroups.com> <28826-4412519C-544@storefull-3255.bay.webtv.net> <1142073802.408256.64360@i40g2000cwc.googlegroups.com> w8ji@akorn.net wrote: > Cecil Moore wrote: >>> Now, it surely is possible to bypass a perfect inductor with a capacitor >>> to mitigate a delay. >> Dang Richard, now you've told Tom how to run his experiment >> in order to obtain the results he predicts. :-) > > You say you will accept something, you ask for something to be done, > and when it is offered you back up and stall, preparing advance excuses > why it won't be done correctly and refusing to make a prediction. > > You've eaten up hours of my time and the only thing I've learned is you > don't want to learn, and you are so unsure of yourself you'll avoid any > prediction of how something will work any way you can. > > I'm just amazed you have to fall back on name calling, mubo-jumbo, and > inuendo when someone offers to help you understand something. I'm all > done with this too. That's exactly what he did back in November 2003. I see he hasn't changed any. Wonder who the next person will be to get sucked in, jerked around, and disgusted. Roy Lewallen, W7EL Article: 222077 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Current through coils References: <1142043207.752336.206250@j52g2000cwj.googlegroups.com> <28826-4412519C-544@storefull-3255.bay.webtv.net> <1142073802.408256.64360@i40g2000cwc.googlegroups.com> Message-ID: <7oyQf.128$tN3.39@newssvr27.news.prodigy.net> Date: Sat, 11 Mar 2006 11:20:35 GMT w8ji@akorn.net wrote: > Cecil Moore wrote: >>Dang Richard, now you've told Tom how to run his experiment >>in order to obtain the results he predicts. :-) > > You say you will accept something, you ask for something to be done, > and when it is offered you back up and stall, preparing advance excuses > why it won't be done correctly and refusing to make a prediction. It was a joke, Tom. I am still trying to work out the measurement details in my mind. It certainly won't do any good to measure a parameter other than the one we want to measure. -- 73, Cecil http://www.qsl.net/w5dxp Article: 222078 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Current through coils References: <1211ig3hafcm451@corp.supernews.com> <1142003771.861185.56110@e56g2000cwe.googlegroups.com> <%yrQf.8704$8w2.3002@bgtnsc04-news.ops.worldnet.att.net> <1142074328.192282.159350@j52g2000cwj.googlegroups.com> Message-ID: Date: Sat, 11 Mar 2006 11:29:57 GMT w8ji@akorn.net wrote: > Cecil also said he wanted a measurement. When I asked him to make a > prediction, he made excuses why any result would be wrong and avoided > any prediction. The concept is easy. The measurement it tricky. It won't do a bit of good to measure the voltage delay and call it the current delay. I asked you pointed questions about your coil and measurement setup. Instead of responding with answers to my questions, you respond with more ad hominem attacks. One wonders what your motive really is. Did your measurements support my side of the argument and now you are ashamed to report those results? If you refuse to make the measurements, I'll just find someone else willing to do it or do it myself. -- 73, Cecil http://www.qsl.net/w5dxp Article: 222079 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Current through coils References: <1142043207.752336.206250@j52g2000cwj.googlegroups.com> <28826-4412519C-544@storefull-3255.bay.webtv.net> <1142073802.408256.64360@i40g2000cwc.googlegroups.com> <1215b6onoaoke41@corp.supernews.com> Message-ID: <3AyQf.130$tN3.83@newssvr27.news.prodigy.net> Date: Sat, 11 Mar 2006 11:33:19 GMT Roy Lewallen wrote: > That's exactly what he did back in November 2003. I see he hasn't > changed any. Wonder who the next person will be to get sucked in, jerked > around, and disgusted. Here comes the junk yard dog guru gang. Tom has refused to give me the necessary needed information about his coil and his measurement configuration and you are blaming me for that? With the information that he has provided so far, I might as well be trying to guess how much loose change he has in his pocket. -- 73, Cecil http://www.qsl.net/w5dxp Article: 222080 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Current through coils References: <1142043207.752336.206250@j52g2000cwj.googlegroups.com> <28826-4412519C-544@storefull-3255.bay.webtv.net> <1142073802.408256.64360@i40g2000cwc.googlegroups.com> <7oyQf.128$tN3.39@newssvr27.news.prodigy.net> Message-ID: <3QyQf.131$tN3.120@newssvr27.news.prodigy.net> Date: Sat, 11 Mar 2006 11:50:23 GMT Cecil Moore wrote: > w8ji@akorn.net wrote: >> You say you will accept something, you ask for something to be done, >> and when it is offered you back up and stall, preparing advance excuses >> why it won't be done correctly and refusing to make a prediction. I'm not stalling, Tom, I'm waiting for you to provide the information I requested. Why are you avoiding providing that information? It's pretty simple stuff that anyone would need to make a prediction. 1. What is the inductance of the coil? What is the Q of the coil? 2. What kind of current probes are you using with your Network Analyzer? What are the characteristics of the driving source signal? 3. What is the schematic configuration of your test setup? How can I possibly make a prediction without that schematic? That is certainly a reasonable request. Without that information, a prediction is impossible, not just for me but for anyone else. -- 73, Cecil http://www.qsl.net/w5dxp Article: 222081 of rec.radio.amateur.antenna From: The BeNevolent dbu Subject: Re: Q. about height of the ends of a doublet References: Message-ID: Date: Sat, 11 Mar 2006 11:53:22 GMT In article , Dave Oldridge wrote: > rocky wrote in > news:mar.sv-A1022D.17240808032006@news-rdr-02.rdc-kc.rr.com: > > > In article , > > Dave Oldridge wrote: > > > >> Big Endian wrote in > >> news:nospam-3801D8.18373207032006@news-rdr-02.rdc-kc.rr.com: > >> > >> > > >> > My center of a 3.8 Mhz doublet is at about 35 feet and am going to > >> > drop the ends from 30 feet to about 10 to 15 feet. Just wondering > >> > if it will make all that much difference if any? > >> > >> There will be a marked improvement in the low angle performance in > >> the direction off the ends of the antenna (the flattop is very poor > >> at this). This will come at the expense of a sight loss (about .8db) > >> off the pattern's top (where you can most afford it). You will also > >> experience a slight deterioration in the SWR (based on 50 ohm coax) > >> from about 1.34 to 2.05, easily managed by any tuner, including those > >> built into many radios. You will also find that you need to shorten > >> the antenna very slightly to maintain the same resonant frequency. > >> > >> This won't make it into a superior DX antenna but it may allow you to > >> hear things you missed before. Basically, Bob Heinlein was right. > >> There ain't any such thing as a free lunch. > > > > What I've read is that when the ends are dropped to an inverted Vee > > configuration the feedpoint impedance drops closer to 50 ohms, but the > > Vee bandwidth is more restricted. Hard to believe that lowering the > > ends by 15 feet from 30 would make all that much difference on 75 > > meters. > > It's only really noticeable on low-angle (about 30 degrees or so) signals > from the direction off the ends. I am going to have both antennas up at the same time. I'll switch between the two and see if there is any difference on close in (100-300 miles) stations hearing me. The antennas will only be a few feet apart, one will be a dipole cut for around 3.8 and fed with 52 ohm coax, the other is a 130 ft. center fed doublet using 450 ladder line. This may take a while because we're still in winter. -- "Welcome to President Clinton, Mrs. Clinton, and my fellow astronauts." Al Gore Article: 222082 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Current through coils References: <1211ig3hafcm451@corp.supernews.com> <1142003771.861185.56110@e56g2000cwe.googlegroups.com> <1142040868.926875.4670@j33g2000cwa.googlegroups.com> <1142078065.701187.54500@i40g2000cwc.googlegroups.com> Message-ID: <0NzQf.132$tN3.62@newssvr27.news.prodigy.net> Date: Sat, 11 Mar 2006 12:55:24 GMT w8ji@akorn.net wrote: > I wrote and all can read: Everyone please take a close look at the lengths to which Tom will go to to deceive the readers. He has falsified the following postings. He mixed and matched, cut and pasted, from multiple postings made at different times for the sole purpose of deceiving. That cannot happen accidentally. That is a deliberately unethical act, a lie about what I posted, and is probably criminal. Please observe to what lengths Tom is willing to go to divert the technical issues and hide the technical truth in order to protect his lumped-circuit myths. Here's is the entire posting: Where did Tom give the coil length? ****************************************************************** w8ji@akorn.net wrote: > I have a 100 turn 2" diameter #18 gauge wire air core inductor. There > are 100 turns, so there is about 630 inches or 32 feet of wire in the > coil. > > I have a Network Analyzer with port to port time delay measurement > capability. It measures coaxial cables very well, and even clip leads. > > Cecil, please predict or guess the group delay of this inductor at 3.8 > MHz. Tell us all what that group delay means for your wave theory. Tom, I have no idea since you chose not to post the length of the coil or the inductance of the coil or the Q of the coil or even the turns/inch of the coil. Is your Network Analyzer equipped with current probes? If not, you are wasting your time. -- 73, Cecil http://www.qsl.net/w5dxp **************************************************************************** > > To which Cecil Moore replied: >>Tom, I have no idea since you chose not to post the length of >>the coil or the inductance of the coil or the Q of the coil >>or even the turns/inch of the coil. That quote is my reply to Tom's *first* posting. I had not read your *second* posting yet. Everything I said was absolutely true about his first posting. How unethical can one get? Tom cut and pasted multiple postings >from different times to try to deceive the readers. Not only is it unethical but it is probably also illegal. -- 73, Cecil http://www.qsl.net/w5dxp Article: 222083 of rec.radio.amateur.antenna From: "Reg Edwards" Subject: Re: Current through coils Date: Sat, 11 Mar 2006 14:37:58 +0000 (UTC) Message-ID: References: <1211ig3hafcm451@corp.supernews.com> <1142003771.861185.56110@e56g2000cwe.googlegroups.com> <1142040868.926875.4670@j33g2000cwa.googlegroups.com> <1142078065.701187.54500@i40g2000cwc.googlegroups.com> <0NzQf.132$tN3.62@newssvr27.news.prodigy.net> Now, now, gentlemen, there's no need to re-start the Civil War. Put away your literary weapons. The slaves have all been freed and we now have computers. A 100 turn coil, 10 inches long, 2 inches in diameter, has an inductance of 102 microhenrys, a Q of aproximately 380 at F = 1.9 MHz, and the self-resonant frequency is 12.0 MHz. Its radiation resistance at 1.9 MHz is negligible. It is near enough to being exactly 100 microhenrys to justify it being called an Inductance Standard. ---- Reg. Article: 222084 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Current through coils References: <1211ig3hafcm451@corp.supernews.com> <1142003771.861185.56110@e56g2000cwe.googlegroups.com> <1142040868.926875.4670@j33g2000cwa.googlegroups.com> <1142078065.701187.54500@i40g2000cwc.googlegroups.com> <0NzQf.132$tN3.62@newssvr27.news.prodigy.net> Message-ID: Date: Sat, 11 Mar 2006 15:04:54 GMT Reg Edwards wrote: > A 100 turn coil, 10 inches long, 2 inches in diameter, has an > inductance of 102 microhenrys, a Q of aproximately 380 at F = 1.9 MHz, > and the self-resonant frequency is 12.0 MHz. Its radiation resistance > at 1.9 MHz is negligible. Good stuff Reg. Modeling it as a transmission line, what would be its Z0 and VF? -- 73, Cecil http://www.qsl.net/w5dxp Article: 222085 of rec.radio.amateur.antenna Subject: Re: Q. about height of the ends of a doublet From: Dave Oldridge References: Message-ID: Date: Sat, 11 Mar 2006 15:57:43 GMT The BeNevolent dbu wrote in news:relaxa.n.d-EE6116.05533211032006@news-rdr-02.rdc-kc.rr.com: > In article , > Dave Oldridge wrote: > >> rocky wrote in >> news:mar.sv-A1022D.17240808032006@news-rdr-02.rdc-kc.rr.com: >> >> > In article , >> > Dave Oldridge wrote: >> > >> >> Big Endian wrote in >> >> news:nospam-3801D8.18373207032006@news-rdr-02.rdc-kc.rr.com: >> >> >> >> > >> >> > My center of a 3.8 Mhz doublet is at about 35 feet and am going >> >> > to drop the ends from 30 feet to about 10 to 15 feet. Just >> >> > wondering if it will make all that much difference if any? >> >> >> >> There will be a marked improvement in the low angle performance in >> >> the direction off the ends of the antenna (the flattop is very >> >> poor at this). This will come at the expense of a sight loss >> >> (about .8db) off the pattern's top (where you can most afford it). >> >> You will also experience a slight deterioration in the SWR (based >> >> on 50 ohm coax) from about 1.34 to 2.05, easily managed by any >> >> tuner, including those built into many radios. You will also find >> >> that you need to shorten the antenna very slightly to maintain the >> >> same resonant frequency. >> >> >> >> This won't make it into a superior DX antenna but it may allow you >> >> to hear things you missed before. Basically, Bob Heinlein was >> >> right. There ain't any such thing as a free lunch. >> > >> > What I've read is that when the ends are dropped to an inverted Vee >> > configuration the feedpoint impedance drops closer to 50 ohms, but >> > the Vee bandwidth is more restricted. Hard to believe that >> > lowering the ends by 15 feet from 30 would make all that much >> > difference on 75 meters. >> >> It's only really noticeable on low-angle (about 30 degrees or so) >> signals from the direction off the ends. > > I am going to have both antennas up at the same time. I'll switch > between the two and see if there is any difference on close in > (100-300 miles) stations hearing me. The antennas will only be a few > feet apart, one will be a dipole cut for around 3.8 and fed with 52 > ohm coax, the other is a 130 ft. center fed doublet using 450 ladder > line. This may take a while because we're still in winter. Assuming the mean RF CURRENT heights are the same and the two antennas are not violently interacting, you shouldn't see much difference. There will, of course always be some phasing differences between two different antennas, even if they are otherwise equal. This cannot be avoided where signals are being reflected off the ionosphere and the ground. -- Dave Oldridge+ ICQ 1800667 Article: 222086 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Current through coils References: <1211ig3hafcm451@corp.supernews.com> <1142003771.861185.56110@e56g2000cwe.googlegroups.com> <1142040868.926875.4670@j33g2000cwa.googlegroups.com> <1142078065.701187.54500@i40g2000cwc.googlegroups.com> <0NzQf.132$tN3.62@newssvr27.news.prodigy.net> Message-ID: Date: Sat, 11 Mar 2006 16:21:26 GMT Reg Edwards wrote: > A 100 turn coil, 10 inches long, 2 inches in diameter, has an > inductance of 102 microhenrys, a Q of aproximately 380 at F = 1.9 MHz, > and the self-resonant frequency is 12.0 MHz. I'll bet the measured self-resonant frequency would be lower if mounted as a base-loading coil on my pickup. Seems the VF of the coil is 0.041 based on 10" being 1/4WL at 12 MHz. Assuming that VF holds down to 1.9 MHz we can calculate the electrical length of the coil on 1.9 MHz which will be the same as the phase shift through the coil. So I get about ~14 degrees of phase shift through that coil at 1.9 MHz assuming the self-resonant frequency really is 12 MHz at the spot where the coil is mounted. If the coil were used on 3.8 MHz, the phase shift would be ~28 degrees. But my 75m bugcatcher coil shows to be self-resonant at 6.6 MHz while sitting there on my pickup being driven by an MFJ-259B. It is 6.5" long. When 6.5" is 1/4WL at 6.6 MHz, the VF = 0.0145, considerably lower than the coil above and operating much closer to its self- resonant frequency. A length of 6.5" coil with a VF of 0.145 on 4 MHz is ~55 degrees of phase shift. And indeed the net current at the top of the coil drops to about 2/3 of what it is at the bottom. -- 73, Cecil http://www.qsl.net/w5dxp Article: 222087 of rec.radio.amateur.antenna From: richardharrison@webtv.net (Richard Harrison) Subject: Re: Current through coils Date: Sat, 11 Mar 2006 10:15:07 -0600 Message-ID: <23728-4412F78B-491@storefull-3254.bay.webtv.net> References: <1211ig3hafcm451@corp.supernews.com> Roy Lewallen, W7EL wrote: "The mathematical treatment in King is quite complex. But nowhere does he mention any traveling, reflected, or standing current, power, or energy waves, or that inductance behaves any differently in an antenna than in a lumped circuit.." Maybe something was overlooked. The above is just more squid ink. Kraus characterizes inductors as helices. At one extreme they are stretched into straifht wires. At the other they collapse into single loops. After years of wrangling it is time to admit that the old authors are right. King and Wing were associates at Harvard. Alexander H. Wing wrote on page 3 of "Transmission Lines, Antennas, and Wave Guides": "5. Distributed constants - The Transmission line cannot be analyzed as a simple series circuit, because the current in the wires is not everywhere the same." J.D. Kraus wrote on page 185 of his 1950 edition of "Antennas": "Thus, a helix with circumference too small for the axial mode of radiation (circumferennce less than 2/3 wavelength) has a nearly sinusoidal current distribution, caused by alternate reinforcement and cancellation of two oppositely directed traveling waves on the helix of nearly equal amplitude Izero as suggested in Fig. 7-13c. Both traveling waves are of the Tzero transmission mode type." I expedct no one will throw in the towel, but do expect more squirts of squid ink. Best regards, Richard Harrison, KB5WZI Article: 222088 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Current through coils References: <1142043207.752336.206250@j52g2000cwj.googlegroups.com> <28826-4412519C-544@storefull-3255.bay.webtv.net> <1142073802.408256.64360@i40g2000cwc.googlegroups.com> Message-ID: <8_CQf.55899$Jd.1369@newssvr25.news.prodigy.net> Date: Sat, 11 Mar 2006 16:34:12 GMT John Popelish wrote: > Dang! I was looking forward to your test results, and a description of > your test method. I think your 2" diameter coil is a good example of an > inductor that is neither a perfect "lump" nor a pure transmission line. That's what my back of the napkin calculations would indicate. I get ~14 degrees at 1.9 MHz or ~28 degrees at 3.8 MHz based on 90 degrees at 12 MHz. But based on what these guys measured before, anyone would be a fool to predict the results without knowing what the test setup looks like. In fact, the prediction challenge was a blatently obvious attempt to lead the unsuspecting down a primrose path without a roadmap. Do you think W7EL would ever make a prediction based on the meager amount of information provided? :-) A few years ago he provided some information but kept changing parameters daily until I got tired and withdrew my estimate. But it turned out in the end that I was pretty close. -- 73, Cecil http://www.qsl.net/w5dxp Article: 222089 of rec.radio.amateur.antenna From: richardharrison@webtv.net (Richard Harrison) Subject: Re: Current through coils Date: Sat, 11 Mar 2006 10:39:21 -0600 Message-ID: <23728-4412FD39-495@storefull-3254.bay.webtv.net> References: Reg wrote: "Now, now gentlemen, there is no need to re-start the Civil War." In Texas we call it the War Between the States! The following is from my daughter Linda Edwards (not related to Reg) who lives in London: The scene is on a mexican golf course and the "Federales" are investigating an apparent homicide. Investigator asks: "What was the murder weapon?" Reply is: "A golf gun." Investigator asks "What`s a golf gun?" Reply is: "Don`t know but it sure made a hole in Juan!" best regards, Richard Harrison, KB5WZI Article: 222090 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Current through coils References: <1211ig3hafcm451@corp.supernews.com> <23728-4412F78B-491@storefull-3254.bay.webtv.net> Message-ID: Date: Sat, 11 Mar 2006 16:52:26 GMT Richard Harrison wrote: > J.D. Kraus wrote on page 185 of his 1950 edition of "Antennas": > "Thus, a helix with circumference too small for the axial mode of > radiation (circumferennce less than 2/3 wavelength) has a nearly > sinusoidal current distribution, caused by alternate reinforcement and > cancellation of two oppositely directed traveling waves on the helix of > nearly equal amplitude Izero as suggested in Fig. 7-13c. Both traveling > waves are of the Tzero transmission mode type." Over on qrz.com, Tom was trying to prove Kraus wrong when he said in "Antennas for All Applications", 3rd edition: "A coil (or trap) can also act as a 180 degree phase shifter as in the collinear array of 4 in-phase 1/2WL elements in Fig. 23-21B. Here the elements present a high impedance to the coil which may be resonated without an external capacitor due to its distributed capacitance. The coil may also be thought of as a coiled-up 1/2WL element." In trying to prove one could not obtain Kraus' 180 degree phase shift with a coil [because everyone knows the phase shift is always zero], Tom accidentally let slip the following - quoted from qrz.com: > W8JI wrote: >> "By the way, I swept S12 phase with my network analyzer on a >> 100uH inductor a few hours ago while working on a phasing >> system. The phase shift through that series inductor was about >> -60 or -70 degrees on 1 MHz, ... " Say what? Tom reporting a phase shift through an inductor? Will miracles never cease? -- 73, Cecil http://www.qsl.net/w5dxp Article: 222091 of rec.radio.amateur.antenna From: "Frank's" References: <6kf8e3-hhc.ln1@p400bob.personal.cox.net> <1142045725.211081.71000@u72g2000cwu.googlegroups.com> Subject: Re: Soil dielectric constand and conductivity for East Texas Message-ID: Date: Sat, 11 Mar 2006 16:57:22 GMT > The measurement method in the Handbook is seriously flawed. You will > almost always measure something many times better than the soil really > is at radio frequencies. > > Since soil conductivity varies widely over small distances, and since > it also has seasonal variations, a rough guess from a book is about as > good as anything. > > Myself, I don't worry about it. I just use average soil in models. > > 73 Tom Thanks for your comments Tom, and you raise some valid points. Jerry Sevick "The Short Vertical Antenna and Ground Radial", pp 25, 26, does state that the procedure is accurate to within 25%, but does not provide any independant verification of these claims. The method was developed by M. C. Waltz at Bell Labs, but, again, nothing was ever published. It would be interesting to develop a more accurate method. While my measurement of 52 mS/m may not be very realistic it is evident that this region does have a very high soil conductivity. Ground-wave daylight reception of AM broadcast stations, with strong signals, at well over 300 miles is possible. 73, Frank Article: 222092 of rec.radio.amateur.antenna From: "Reg Edwards" Subject: Re: Current through coils Date: Sat, 11 Mar 2006 17:39:42 +0000 (UTC) Message-ID: References: <1211ig3hafcm451@corp.supernews.com> <23728-4412F78B-491@storefull-3254.bay.webtv.net> "Richard Harrison" wrote > Kraus characterizes inductors as helices. At one extreme they are > stretched into straifht wires. At the other they collapse into single > loops. ===================================== See program SOLNOID3 which calculates inductance of 1-turn loops, via multi-turn solenoids, to straight wires. With many other parameters of interest such as temperature rise for a given applied voltage, as in tank circuits and antenna loading coils. So far as the author is aware there are no bugs in it. It's been around and much used for a few years. ---- ........................................................... Regards from Reg, G4FGQ For Free Radio Design Software go to http://www.btinternet.com/~g4fgq.regp ........................................................... Article: 222093 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Current through coils References: <1142043207.752336.206250@j52g2000cwj.googlegroups.com> <28826-4412519C-544@storefull-3255.bay.webtv.net> <1142073802.408256.64360@i40g2000cwc.googlegroups.com> <8_CQf.55899$Jd.1369@newssvr25.news.prodigy.net> Message-ID: Date: Sat, 11 Mar 2006 18:00:04 GMT John Popelish wrote: > Predictions are little more than an ego trip, unless they are a test of > a specific calculation method used for the prediction. But I was > willing to wait for the test result and an after the fact description of > the test method, to see what understanding might be teased out that > combination of facts. The discussion might also have lead to a better > way to perform such a test. Still might. But I suspect the test results are already available and just being withheld because someone doesn't like the results. I'm a skeptical, suspicious type. I'm sure Tom wishes he had not published his "-60 to -70 degree phase shift" results. -- 73, Cecil http://www.qsl.net/w5dxp Article: 222094 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Current through coils References: <1211ig3hafcm451@corp.supernews.com> <23728-4412F78B-491@storefull-3254.bay.webtv.net> Message-ID: Date: Sat, 11 Mar 2006 18:18:21 GMT Reg Edwards wrote: > See program SOLNOID3 which calculates inductance of 1-turn loops, via > multi-turn solenoids, to straight wires. Reg, at http://www.ttr.com/TELSIKS2001-MASTER-1.pdf equation (43) gives the helical wave guide effective characteristic impedance. Unfortunately, that web site is not responding at the moment (probably because all the gurus here are accessing it wondering what they did wrong.) :-) But, when the page becomes available would you take a look at that equation? It goes something like this: Zc = 60/Vf[I0(tau*alpha)*K0(tau*alpha)] Is tau the transmission coefficient and alpha the attenuation constant? Are I0 and K0 functions? Have you ever seen this equation before? Also, Fig. 1 is a graph of velocity factor vs the diameter of the helix divided by the wavelength for 10k, 5k, 2.5k, 1k, 500, 250, 100, and 50 turns per wavelength. It says: "Tightly wound coils are slow wave structures." My 75m bugcatcher coil appears to fall nicely into the catagory of a "tightly wound slow wave structure". -- 73, Cecil http://www.qsl.net/w5dxp Article: 222095 of rec.radio.amateur.antenna Message-ID: <44131BE0.B02A5333@shaw.ca> From: Irv Finkleman Subject: Re: Dipole Extension References: Date: Sat, 11 Mar 2006 18:49:56 GMT "Dick, AA5VU" wrote: > > Late yesterday afternoon I decided to try the two alligator clips and > some wire to run a test to see what would happen. Sounds easy but I > made it very hard. > > Dick AA5VU (red-faced) Atta Ham! :-) I'm pretty sure we've all done things like that! At least I have -- more than once too! 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: 222096 of rec.radio.amateur.antenna From: "Reg Edwards" Subject: Re: Current through coils Date: Sat, 11 Mar 2006 18:55:02 +0000 (UTC) Message-ID: References: <1211ig3hafcm451@corp.supernews.com> <1142003771.861185.56110@e56g2000cwe.googlegroups.com> <1142040868.926875.4670@j33g2000cwa.googlegroups.com> <1142078065.701187.54500@i40g2000cwc.googlegroups.com> <0NzQf.132$tN3.62@newssvr27.news.prodigy.net> <1142098219.644998.299540@j52g2000cwj.googlegroups.com> The phase shift along a coil, an inductor, considered as a transmission line, obviously depends on what it is terminated with. It much depends on frequency. In the present context, the termination of the coil is the input impedance of another transmission line consisting of a rod or length of wire, or a capacitance hat, forming the remainder of the antenna. To the participants to this discussion, just think about it. The behaviour of the coil depends on the behaviour of the rest of the system. On the other hand, a coil has certain fixed parameters which are independent of the rest of the system. It is a good idea to restrict analysis to the resonant frequency of the system. It assists with simpification and understanding of it. Tonight, I've switched to Western Austalian dry white. ---- Reg. Article: 222097 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Current through coils References: <1141929188.910581.171220@p10g2000cwp.googlegroups.com> <1211ig3hafcm451@corp.supernews.com> <1142003771.861185.56110@e56g2000cwe.googlegroups.com> <1142043207.752336.206250@j52g2000cwj.googlegroups.com> Message-ID: Date: Sat, 11 Mar 2006 19:14:37 GMT w8ji@akorn.net wrote: > Cecil, > You have consistently disagreed with me when I said time delay through > an inductor with tight mutual coupling from turn-to-turn is somewhat > close to light speed over the physical length of the inductor, rather > than the time it takes current to wind its way around through the > copper. I think I have figured out your misunderstanding here, Tom. I *never* said the current winds its way around through the copper. That was just another one of your strawmen that I don't believe and have never believed. I have offered you $100 if you can find where I ever said that. Would it make any difference if I offered you $1000? The effect of a velocity factor of 0.015 may seem to you to be the same as "current winds its way around through the copper" but I assure you, if you understood the wave model of distributed network analysis, you would understand why that is not the case. I can fully understand why someone so emotionally attached to the lumped-circuit model would assume "current winding its way around through the copper" but that is simply a misconception of yours. Distributed networks are not nearly as simple-minded as your lumped-circuits. A helical coil structure with a VF of 0.015 *is what it is*. Waves propagate at 0.015 the speed of light and that's quite a delay through a relatively physically short coil. If the coil is 6.5 inches long, as is my 75m bugcatcher coil, it occupies an electrical length of 6.5"/.015 = 433" = 36 feet. The fact that it consumes 42 feet of wire is just a coincidence. The 6.5" coil replaces aabout 36' of straight wire. From those facts, you can calculate the number of degrees or percentage of a wavelength. Shirley, you understand that 1/4WL of a transmission line with a 0.9 velocity factor is longer than 1/4WL of line with a 0.66 velocity factor. That's why coax stubs are shorter than 450 ohm ladder-line stubs. (I feel like I'm doing a EE323 tutorial here). What is it about a VF of 0.015 that you don't understand? All it means is that RF through the coil is traveling at 1/67 the speed of light. If you understand that RF through RG-8 is traveling at 2/3 the speed of light, why can't you understand "slow wave coils"? -- 73, Cecil http://www.qsl.net/w5dxp Article: 222098 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Current through coils References: <1211ig3hafcm451@corp.supernews.com> <1142003771.861185.56110@e56g2000cwe.googlegroups.com> <1142040868.926875.4670@j33g2000cwa.googlegroups.com> <1142078065.701187.54500@i40g2000cwc.googlegroups.com> <0NzQf.132$tN3.62@newssvr27.news.prodigy.net> <1142098219.644998.299540@j52g2000cwj.googlegroups.com> Message-ID: Date: Sat, 11 Mar 2006 19:21:24 GMT Reg Edwards wrote: > To the participants to this discussion, just think about it. The > behaviour of the coil depends on the behaviour of the rest of the > system. i.e. the behavior of the coil depends upon the reflected energy in the system delivered back to the coil by other elements in the system. That's basically why the lumped- constant model fails. > Tonight, I've switched to Western Austalian dry white. "Austalian"? You've got two choices, Reg. Sober up or have another. I would have another. :-) But please note, you have given up a lot of antioxidants from the reds. -- 73, Cecil http://www.qsl.net/w5dxp Article: 222099 of rec.radio.amateur.antenna From: "Reg Edwards" Subject: Re: Dipole Extension Date: Sat, 11 Mar 2006 19:27:38 +0000 (UTC) Message-ID: References: "aRKay" wrote > You are correct but many of us tend to get obsessive about SWR. ===================================== Quite right too! Extremely few SWR meters indicate SWR on the transmission line from transmitter to the antenna where it really might matter but seldom doesn't. All that is indicated is whether or not the transmitter is loaded with its correct impedance. Admittedly, a useful indication. The learned discussions on the subject of interpretting SWR meter redings are usually so much baffle-gab. ---- Reg. Article: 222100 of rec.radio.amateur.antenna From: Roy Lewallen Subject: Re: Current through coils Date: Sat, 11 Mar 2006 12:51:54 -0800 Message-ID: <1216e3dskf72sa3@corp.supernews.com> References: <1142043207.752336.206250@j52g2000cwj.googlegroups.com> <28826-4412519C-544@storefull-3255.bay.webtv.net> <1142073802.408256.64360@i40g2000cwc.googlegroups.com> <8_CQf.55899$Jd.1369@newssvr25.news.prodigy.net> John Popelish wrote: > Cecil Moore wrote: >> >> . . . Do you think W7EL would >> ever make a prediction based on the meager amount of >> information provided? :-) A few years ago he provided some >> information but kept changing parameters daily until I got >> tired and withdrew my estimate. But it turned out in the >> end that I was pretty close. That's entirely untrue. The record is readily available via groups.google.com for anyone interested in seeing what really happened. The thread was "Current in antenna loading coils controversy (long)", in November 2003. > . . . Roy Lewallen, W7EL Article: 222101 of rec.radio.amateur.antenna From: "Dick, AA5VU" Subject: Re: Dipole Extension (done) References: Message-ID: Date: Sat, 11 Mar 2006 21:00:00 GMT In article , "Dick, AA5VU" wrote: > In article , > "Dale Parfitt" wrote: > > > I am not familair with this antenna, but if it has a choke/trap for 40M, > > just add a foot of wire on the side of the choke/trap that is closest to > > the > > center insulator- let it hang down and dangle. You can clip it on as one > > poster said- this is a high Z point and contact resistance is a non-issue. > > But as others have said, the on-air difference is zero. > > > > Dale W4OP > > Late yesterday afternoon I decided to try the two alligator clips and > some wire to run a test to see what would happen. Sounds easy but I > made it very hard. To make a long shaggy-dog story short I added the > wire and the SWR went out of sight. It acted like a dead short. I then > lowered he antenna and cut the wire in half and it was still terrible. > I then trashed he alligator clips and wire to and it was still > terrible. After two hours of screwing around, I found some dummy (me) > had the coax switch on the old Ringo Ranger rather than the W9INN > antenna. By this time it was too dark to mess with anything. > > Going to start over when the sun comes up but this time I plan to ditch > the alligator clips and attach a one foot wire using the connection nuts > on the coil/trap or whatever w9inn used to call that thing between the > 40 and 80 wires and will have the coax switch on the right antenna this > time. > > Dick AA5VU (red-faced) The antenna now lives! This morning I added a 14-inch wire to each leg by attaching it to nut on the 40 meter side of coil/trap thing. The experiment worked so I know how much I need to cut and solder in on he 40 meter dipole. I may run with the 14-inch wire whips for a week or so and see what happens. The following is a list of the before and after SWR readings. The 14" addition did just what the book said it would do. I now have the 40 meter resonant point pretty close to where I want it for PSK and RTTY but can still use the phone band as well. 7.600 1.8 7.500 1.4 2.0 7.400 1.1 1.8 7.300 1.1 1.3 7.200 1.4 1.1 7.100 1.7 1.1 7.050 1.8 1.3 7.000 1.8 1.4 6.900 2.0 1.6 6.800 - 2.0 The 50 MHz, 18 MHz, 24 MHz and 3.9 MHz readings did not change and they are all 1.1 or very close. Bill, W9INN, will be missed. He was a great guy and his antennas were excellent. Too bad nobody picked up the ball from him. My old 40/80 W9INN has been modified to add WARC bands but still works great after 20 years of use and abuse. The traps are still in good shape. TNX for reading 73, Dick AA5VU Article: 222102 of rec.radio.amateur.antenna From: Roy Lewallen Subject: Re: Soil dielectric constand and conductivity for East Texas Date: Sat, 11 Mar 2006 13:06:32 -0800 Message-ID: <1216ev1fa39ak9a@corp.supernews.com> References: <6kf8e3-hhc.ln1@p400bob.personal.cox.net> <1142045725.211081.71000@u72g2000cwu.googlegroups.com> Frank's wrote: > > Thanks for your comments Tom, and you raise some valid points. Jerry Sevick > "The Short Vertical Antenna and Ground Radial", pp 25, 26, does state that > the procedure is accurate to within 25%, but does not provide any > independant verification of these claims. The method was developed by M. C. > Waltz at Bell Labs, but, again, nothing was ever published. > > It would be interesting to develop a more accurate method. While my > measurement of 52 mS/m may not be very realistic it is evident that this > region does have a very high soil conductivity. Ground-wave daylight > reception of AM broadcast stations, with strong signals, at well over 300 > miles is possible. There are more accurate methods to calculate ground conductivity, but what's the point? The skin depth in soil is on the order of 10 or 20 feet, depending on the frequency and soil quality. This means that substantial current is flowing down to a few times this depth. Certainly where I live, and I'd bet that in most locations, the conductivity is far from uniform. So in order to know the conductivity of the soil which is carrying current, you'd need to measure it down to several tens of feet. Once you had that data, what would you do with it? Currently available modeling programs assume homogeneous ground to an infinite depth. So you'd have to choose some single value from among your measurements if your objective is to get better accuracy from a program. But there's no evidence that a homogeneous ground with any single value of conductivity will behave the same as a stratified ground. So having even an extremely accurate measure of surface conductivity at a particular radio frequency (and it does vary with frequency) still gives you much too little information to build even a crudely accurate model of the actual ground in which the current is flowing. Roy Lewallen, W7EL Article: 222103 of rec.radio.amateur.antenna From: Win Subject: KLM C-3 Date: Sat, 11 Mar 2006 15:16:11 -0600 Message-ID: I have a freind, a new ham, that was given a 2 meter vetically and horixontally polorized antenna from an estate. The antenna is marked KLM C-3. It had two 300 ohm driven elements. It also has a switching circuit that apparently attaches to the feed points. Can anyone that is familure with this antenna give me information on how to use this circuit to feed tha antenna. Win, w0lz Article: 222104 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Current through coils References: <1142043207.752336.206250@j52g2000cwj.googlegroups.com> <28826-4412519C-544@storefull-3255.bay.webtv.net> <1142073802.408256.64360@i40g2000cwc.googlegroups.com> <8_CQf.55899$Jd.1369@newssvr25.news.prodigy.net> <1216e3dskf72sa3@corp.supernews.com> Message-ID: Date: Sat, 11 Mar 2006 21:38:51 GMT Roy Lewallen wrote: > John Popelish wrote: > >> Cecil Moore wrote: >>> . . . Do you think W7EL would >>> ever make a prediction based on the meager amount of >>> information provided? :-) A few years ago he provided some >>> information but kept changing parameters daily until I got >>> tired and withdrew my estimate. But it turned out in the >>> end that I was pretty close. > > The record is readily available via > groups.google.com for anyone interested in seeing what really happened. > The thread was "Current in antenna loading coils controversy (long)", in > November 2003. Yes, indeed, it is, Roy. That's also my reference. And I have learned a lot of the details underlying your myths since then. -- 73, Cecil http://www.qsl.net/w5dxp Article: 222105 of rec.radio.amateur.antenna From: John Ferrell Subject: Re: Dipole Extension (done) Message-ID: References: Date: Sat, 11 Mar 2006 21:55:37 GMT I am glad to hear it now meets your expectations. I still have not found a diagram of your antenna, but I did find this very good artical on SWR: http://www.qsl.net/k2hq/swr.htm#PART%201 On Sat, 11 Mar 2006 21:00:00 GMT, "Dick, AA5VU" wrote: > >The antenna now lives! This morning I added a 14-inch wire to each leg >by attaching it to nut on the 40 meter side of coil/trap thing. The >experiment worked so I know how much I need to cut and solder in on he >40 meter dipole. I may run with the 14-inch wire whips for a week or so >and see what happens. The following is a list of the before and after >SWR readings. The 14" addition did just what the book said it would do. >I now have the 40 meter resonant point pretty close to where I want it >for PSK and RTTY but can still use the phone band as well. > >7.600 1.8 >7.500 1.4 2.0 >7.400 1.1 1.8 >7.300 1.1 1.3 >7.200 1.4 1.1 >7.100 1.7 1.1 >7.050 1.8 1.3 >7.000 1.8 1.4 >6.900 2.0 1.6 >6.800 - 2.0 > >The 50 MHz, 18 MHz, 24 MHz and 3.9 MHz readings did not change and >they are all 1.1 or very close. > >Bill, W9INN, will be missed. He was a great guy and his antennas were >excellent. Too bad nobody picked up the ball from him. My old 40/80 >W9INN has been modified to add WARC bands but still works great after 20 >years of use and abuse. The traps are still in good shape. > >TNX for reading > >73, Dick AA5VU John Ferrell W8CCW Article: 222106 of rec.radio.amateur.antenna From: "Dale Parfitt" References: Subject: Re: Dipole Extension (done) Message-ID: <2%HQf.12296$wH5.7544@trnddc02> Date: Sat, 11 Mar 2006 22:16:30 GMT >> >> > I am not familair with this antenna, but if it has a choke/trap for >> > 40M, >> > just add a foot of wire on the side of the choke/trap that is closest >> > to >> > the >> > center insulator- let it hang down and dangle. You can clip it on as >> > one >> > poster said- this is a high Z point and contact resistance is a >> > non-issue. >> > But as others have said, the on-air difference is zero. >> > >> > Dale W4OP >> > > The antenna now lives! This morning I added a 14-inch wire to each leg > by attaching it to nut on the 40 meter side of coil/trap thing. The > experiment worked so I know how much I need to cut and solder in on he > 40 meter dipole. I may run with the 14-inch wire whips for a week or so > and see what happens. The following is a list of the before and after > SWR readings. The 14" addition did just what the book said it would do. > I now have the 40 meter resonant point pretty close to where I want it > for PSK and RTTY but can still use the phone band as well. > Absolutely zero reason to place that wire in series with the dipole- in fact it will not yield the same results if you do so- you will end up having to redo the length. It will also mechanically weaken the antenna and also change 80M resonance. There is no current in that short stub-i.e. no effect on radiation. Let it dangle. Dale W4OP Article: 222107 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Current through coils References: <1142043207.752336.206250@j52g2000cwj.googlegroups.com> <28826-4412519C-544@storefull-3255.bay.webtv.net> <1142073802.408256.64360@i40g2000cwc.googlegroups.com> <8_CQf.55899$Jd.1369@newssvr25.news.prodigy.net> <1216e3dskf72sa3@corp.supernews.com> Message-ID: Date: Sat, 11 Mar 2006 22:22:47 GMT Roy Lewallen wrote: > The record is readily available via > groups.google.com for anyone interested in seeing what really happened. > The thread was "Current in antenna loading coils controversy (long)", in > November 2003. At that time in 2003, I was as naive as Galileo in front of the court run by religious priests. Any time you feel like apologizing for your questionable behavior, all I ask is that you retract that single "gobbledygook" statement that you made against my use of the rules of the distributed-network model and laws of reflection physics which are both a subset of Maxwell's equations. -- 73, Cecil http://www.qsl.net/w5dxp Article: 222108 of rec.radio.amateur.antenna From: Bob Bob Subject: Re: Soil dielectric constand and conductivity for East Texas References: <6kf8e3-hhc.ln1@p400bob.personal.cox.net> <1142045725.211081.71000@u72g2000cwu.googlegroups.com> <1216ev1fa39ak9a@corp.supernews.com> Message-ID: Date: Sat, 11 Mar 2006 16:20:35 -0600 Hi Roy.. And I only wanted a simple answer. Was just trying to limit some of the variables and learn some at the same time! The FCC map says its roughly 8 mS/M here... That will do.. Cheers Bob VK2YQA Roy Lewallen wrote: > > There are more accurate methods to calculate ground conductivity, but > what's the point? The skin depth in soil is on the order of 10 or 20 > feet, depending on the frequency and soil quality. This means that Article: 222109 of rec.radio.amateur.antenna From: Bob Bob Subject: Re: KLM C-3 References: Message-ID: Date: Sat, 11 Mar 2006 16:29:07 -0600 Hi Win Without actually looking up the model/manufacturer I'd say it is an antenna meant for circular polarised satellite work. The switching system probably changes LHCP RHCP but may also have a planar (V or H) mode. Now doing a websearch; KLM Antennas - Closed factory - Out of Business the last day of Oct. 1999 - See M2 inc have KLM spares This may be it; http://msuarc.egr.msu.edu/retrofit/klmspecs.html Cheers Bob VK2YQA Win wrote: > > I have a freind, a new ham, that was given a 2 meter vetically and > horixontally polorized antenna from an estate. The antenna is marked > KLM C-3. It had two 300 ohm driven elements. It also has a switching > circuit that apparently attaches to the feed points. > > Can anyone that is familure with this antenna give me information on > how to use this circuit to feed tha antenna. > > Win, w0lz Article: 222110 of rec.radio.amateur.antenna From: "Tom Donaly" Subject: Re: Current through coils References: <1142043207.752336.206250@j52g2000cwj.googlegroups.com> <28826-4412519C-544@storefull-3255.bay.webtv.net> <1142073802.408256.64360@i40g2000cwc.googlegroups.com> <8_CQf.55899$Jd.1369@newssvr25.news.prodigy.net> <1216e3dskf72sa3@corp.supernews.com> Message-ID: Date: Sun, 12 Mar 2006 00:13:21 GMT Cecil Moore wrote: > Roy Lewallen wrote: > >> The record is readily available via groups.google.com for anyone >> interested in seeing what really happened. The thread was "Current in >> antenna loading coils controversy (long)", in November 2003. > > > At that time in 2003, I was as naive as Galileo in front > of the court run by religious priests. > > Any time you feel like apologizing for your questionable > behavior, all I ask is that you retract that single > "gobbledygook" statement that you made against my use of > the rules of the distributed-network model and laws of > reflection physics which are both a subset of Maxwell's > equations. Cecil, have you ever read the book _Don Quixote_, by Cervantes? There's a character in there you remind me of. 73, Tom Donaly, KA6RUH Article: 222111 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Current through coils References: <1142043207.752336.206250@j52g2000cwj.googlegroups.com> <28826-4412519C-544@storefull-3255.bay.webtv.net> <1142073802.408256.64360@i40g2000cwc.googlegroups.com> <8_CQf.55899$Jd.1369@newssvr25.news.prodigy.net> <1216e3dskf72sa3@corp.supernews.com> <1142118071.694172.312130@p10g2000cwp.googlegroups.com> Message-ID: Date: Sun, 12 Mar 2006 00:34:50 GMT w8ji@akorn.net wrote: > I offered to make a measurement if he would even loosely predict > results and tell us in advance what they would mean. When he didn't > respond, I made the measurements anyway. Huh? I predicted 14 degrees at 1.9 MHz and 28 degrees at 3.8 MHz based on Reg's assertion that the coil was self-resonant at 12 MHz. Once you know the self-resonant frequency, the VF can be calculated. From there, one can calculate a ballpark delay through the coil. Your 3 nS measurement seems outside of all possiblity. This is really simple physics, Tom. If your measurements disagree with the boundary conditions set by the laws of distributed- network physics then something is wrong with your measurements. Let's take a closer look. If the delay through the coil is indeed 3 nS at 4 MHz, the phase shift through the coil at 4 MHz is 4.32 degrees. For a self-resonant phase shift of 90 degrees, the self- resonant frequency of the coil has to be near (90/4.32)4 MHz = 83 MHz. Now if the self-resonant frequency is really 83 MHz, all is well, and your measurements agree with distributed network theory. But, Tom, don't you think you are insulting our intelligence when your 100uH coil must have a self-resonant frequency of 83 MHz and a velocity factor of 0.28 for your measurements to be valid? My 75m bugcatcher coil has a VF of 0.015. Why is your coil 20 times better than my bugcatcher? And I have that same coil with 68.5 turns but it is self-resonant at 57 MHz. How do you explain 2/3 of the number of turns being self-resonant 25 MHz lower? If you cannot, something is wrong with your measurements. Don't you care that your 3 nS results are so outside the bounds of possibility as to be laughable? Please measure the self-resonant frequency of that coil, Tom. If it's not 83 MHz, your measurements are bogus. I suggest the self-resonant frequency is actually lower than the 12 MHz predicted by Reg. Incidentally, the IEEE would surely be interested in your ability to violate the distributed-network laws of physics. Maybe you can talk them into replacing that body of physics with your pet lumped-circuit model. Good luck on that one. 3 nS delay through a 100 uH coil???? That would be funny if it was April First. That's why I requested that you describe your test setup which you refused to do. -- 73, Cecil http://www.qsl.net/w5dxp Article: 222112 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Current through coils References: <1142043207.752336.206250@j52g2000cwj.googlegroups.com> <28826-4412519C-544@storefull-3255.bay.webtv.net> <1142073802.408256.64360@i40g2000cwc.googlegroups.com> <8_CQf.55899$Jd.1369@newssvr25.news.prodigy.net> <1216e3dskf72sa3@corp.supernews.com> <3km6129fovbk7bi68e276bgg56ivv66ngr@4ax.com> Message-ID: <52KQf.75237$PL5.1765@newssvr11.news.prodigy.com> Date: Sun, 12 Mar 2006 00:36:17 GMT Richard Clark wrote: > Cecil Moore wrote: >>I was as naive as Galileo in front of the court run by religious priests. > > Has Cecileo been dropping his balls off of the Tower of Pisa again? :-) I dropped them off the wrong side and rewrote the law of gravity. -- 73, Cecil http://www.qsl.net/w5dxp Article: 222113 of rec.radio.amateur.antenna Date: Sat, 11 Mar 2006 19:27:17 -0600 From: Tom Ring Subject: Re: Current through coils References: <1211ig3hafcm451@corp.supernews.com> <23728-4412F78B-491@storefull-3254.bay.webtv.net> <8n1612lon2ba50kin6uk1mhicjdn9q6etc@4ax.com> Message-ID: <441378f5$0$7335$39cecf19@news.twtelecom.net> Richard Clark wrote: > Analog designers, fully expecting a continuum of results spanning from > classic to truly exaggerated, can cope with this. For digital > designers, this is a clear example of confounding expectations of a > binary result. > > 73's > Richard Clark, KB7QHC I've worked with a few digital designers. Many of them expect a unary result. tom K0TAR Article: 222114 of rec.radio.amateur.antenna From: "Dick, AA5VU" Subject: Re: Dipole Extension (done) References: <2%HQf.12296$wH5.7544@trnddc02> Message-ID: Date: Sun, 12 Mar 2006 01:57:57 GMT In article <2%HQf.12296$wH5.7544@trnddc02>, "Dale Parfitt" wrote: > Absolutely zero reason to place that wire in series with the dipole- in fact > it will not yield the same results if you do so- you will end up having to > redo the length. It will also mechanically weaken the antenna and also > change 80M resonance. There is no current in that short stub-i.e. no effect > on radiation. Let it dangle. > Dale W4OP Thanks..... going to let it dangle. Not hurting anything and it has a good attachment. Article: 222115 of rec.radio.amateur.antenna From: "Dick, AA5VU" Subject: Description of W9INN 40/80 dipole References: Message-ID: Date: Sun, 12 Mar 2006 02:04:52 GMT In article , John Ferrell wrote: > I am glad to hear it now meets your expectations. I still have not > found a diagram of your antenna, but I did find this very good artical > on SWR: > http://www.qsl.net/k2hq/swr.htm#PART%201 John, If you recall the old W9INN ads in QST you he has a 40/80 dipole. It was full size 40 meter dipole with what I remember he called a resister (that was really a coil) and about a 9 foot length of wire past the coil for the 80 meter antenna. It was fed with coax to a center insulator. Bill did not believe in baluns. I modified the antenna by two sets of wires. One for 10 MHz and the other for 18 MHz. The 18 MHz seems to be resonant for 6 meters and the whole mess works on 24 MHz as well. I did not see it on the K2HG web page 73, Dick AA5VU Article: 222116 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Current through coils References: <1142043207.752336.206250@j52g2000cwj.googlegroups.com> <28826-4412519C-544@storefull-3255.bay.webtv.net> <1142073802.408256.64360@i40g2000cwc.googlegroups.com> <8_CQf.55899$Jd.1369@newssvr25.news.prodigy.net> <1216e3dskf72sa3@corp.supernews.com> <1142118071.694172.312130@p10g2000cwp.googlegroups.com> <1142124494.851152.85460@j52g2000cwj.googlegroups.com> Message-ID: Date: Sun, 12 Mar 2006 02:15:56 GMT w8ji@akorn.net wrote: > The self-resonant frequency of the inductor is shown by a large rise in > time delay. Cecil is now trying to rewrite the self-resonant frequency > of the inductor I tested by using his own seriously flawed theories, > but despite the fact it appears to be clearly shown in the network > analyzer data at about 16 MHz. Well then, if 10" is 1/4WL at 16 MHz, its velocity factor is 0.054. 10" on 4 MHz with a VF of 0.054 is 0.063WL or 22.6 degrees. Why didn't you measure 22.6 degrees or 15.7 nS of delay? You measured 3 nS or 4.32 degrees of delay. Something is obviously wrong. The VF couldn't change by a factor of 5 to 1 going from 16 MHz to 4 Mhz. I think I know what happened. You forgot and left the test wire attached in parallel with the test coil. :-) -- 73, Cecil http://www.qsl.net/w5dxp Article: 222117 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Current through coils References: <1142043207.752336.206250@j52g2000cwj.googlegroups.com> <28826-4412519C-544@storefull-3255.bay.webtv.net> <1142073802.408256.64360@i40g2000cwc.googlegroups.com> <8_CQf.55899$Jd.1369@newssvr25.news.prodigy.net> <1216e3dskf72sa3@corp.supernews.com> Message-ID: Date: Sun, 12 Mar 2006 02:29:51 GMT Tom Donaly wrote: > Cecil, have you ever read the book _Don Quixote_, by Cervantes? > There's a character in there you remind me of. Tom, please don't tell me that you also believe that a distributed- network analysis using wave reflection theory is "gobbledygook". -- 73, Cecil http://www.qsl.net/w5dxp Article: 222118 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Current through coils References: <1142043207.752336.206250@j52g2000cwj.googlegroups.com> <28826-4412519C-544@storefull-3255.bay.webtv.net> <1142073802.408256.64360@i40g2000cwc.googlegroups.com> <8_CQf.55899$Jd.1369@newssvr25.news.prodigy.net> <1216e3dskf72sa3@corp.supernews.com> <1142118071.694172.312130@p10g2000cwp.googlegroups.com> <1142124494.851152.85460@j52g2000cwj.googlegroups.com> Message-ID: Date: Sun, 12 Mar 2006 02:35:35 GMT Cecil Moore wrote: > w8ji@akorn.net wrote: >> The self-resonant frequency of the inductor is shown by a large rise in >> time delay. Cecil is now trying to rewrite the self-resonant frequency >> of the inductor I tested by using his own seriously flawed theories, >> but despite the fact it appears to be clearly shown in the network >> analyzer data at about 16 MHz. In case my previous reply was confusing to some people let's do it with a piece of transmission line. We have a piece of transmission line that we measure to be 1/4 wavelength on 16 MHz. That's easily done with an MFJ- 259B. We hand it over to Tom who takes it and measures a 3 nS delay through it at 4 MHz. What's wrong with this picture? -- 73, Cecil http://www.qsl.net/w5dxp Article: 222119 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Current through coils References: <1142043207.752336.206250@j52g2000cwj.googlegroups.com> <28826-4412519C-544@storefull-3255.bay.webtv.net> <1142073802.408256.64360@i40g2000cwc.googlegroups.com> <8_CQf.55899$Jd.1369@newssvr25.news.prodigy.net> <1216e3dskf72sa3@corp.supernews.com> <1142118071.694172.312130@p10g2000cwp.googlegroups.com> <1142124494.851152.85460@j52g2000cwj.googlegroups.com> Message-ID: Date: Sun, 12 Mar 2006 03:36:53 GMT w8ji@akorn.net wrote: > Cecil's normal tactic is to change what other people say. I could never bring myself to cut and paste and mix and match numerous postings over many hours to try to twist what someone has said, like you did with my postings. I could ask, Tom are you a criminal?, and wait for the next time you posted a yes to some other question. Cut and paste those two things together and I would be using W8JI's arguing technique. But you know what you are, Tom, without me having to point it out. > To read a > history of the very same behavior with someone else please read: > > http://www.w8ji.com/RRAA_post.htm That is really funny, Tom. You are defending the lumped-constant model, known to fail in a standing wave environment, by measuring standing wave current? You are really something else. -- 73, Cecil http://www.qsl.net/w5dxp Article: 222120 of rec.radio.amateur.antenna From: "Frank" References: <6kf8e3-hhc.ln1@p400bob.personal.cox.net> <1142045725.211081.71000@u72g2000cwu.googlegroups.com> <1216ev1fa39ak9a@corp.supernews.com> Subject: Re: Soil dielectric constand and conductivity for East Texas Message-ID: Date: Sun, 12 Mar 2006 04:31:15 GMT > There are more accurate methods to calculate ground conductivity, but > what's the point? The skin depth in soil is on the order of 10 or 20 feet, > depending on the frequency and soil quality. This means that substantial > current is flowing down to a few times this depth. Certainly where I live, > and I'd bet that in most locations, the conductivity is far from uniform. > So in order to know the conductivity of the soil which is carrying > current, you'd need to measure it down to several tens of feet. > > Once you had that data, what would you do with it? Currently available > modeling programs assume homogeneous ground to an infinite depth. So you'd > have to choose some single value from among your measurements if your > objective is to get better accuracy from a program. But there's no > evidence that a homogeneous ground with any single value of conductivity > will behave the same as a stratified ground. > > So having even an extremely accurate measure of surface conductivity at a > particular radio frequency (and it does vary with frequency) still gives > you much too little information to build even a crudely accurate model of > the actual ground in which the current is flowing. > > Roy Lewallen, W7EL Certainly, all valid points. I was more interested in actually doing precise measurements, but considered it might improve my model accuracy. I even thought of digging a hole to see how the soil varied. Doubt I would have dug down 20 or 30 ft. Most of the ground here is clay, and then probably bedrock, at this elevation of just over 4,000 ft ASL. Ansoft's HFSS, or CST, could probably handle an accurate, stratified, ground model. Frank Article: 222121 of rec.radio.amateur.antenna From: Win Subject: Re: KLM C-3 Date: Sat, 11 Mar 2006 22:39:03 -0600 Message-ID: References: Thanks, Bob. You got it right without looking at it. From your post I took the KLM 2m-14c number and found the manual on line. All is clear now. Thanks, again. Win, w0lz >Hi Win > >Without actually looking up the model/manufacturer I'd say it is an >antenna meant for circular polarised satellite work. The switching >system probably changes LHCP RHCP but may also have a planar (V or H) mode. > >Now doing a websearch; > >KLM Antennas - Closed factory - Out of Business the last day of Oct. >1999 - See M2 inc have KLM spares > >This may be it; > >http://msuarc.egr.msu.edu/retrofit/klmspecs.html > >Cheers Bob VK2YQA > >Win wrote: >> >> I have a freind, a new ham, that was given a 2 meter vetically and >> horixontally polorized antenna from an estate. The antenna is marked >> KLM C-3. It had two 300 ohm driven elements. It also has a switching >> circuit that apparently attaches to the feed points. >> >> Can anyone that is familure with this antenna give me information on >> how to use this circuit to feed tha antenna. >> >> Win, w0lz Article: 222122 of rec.radio.amateur.antenna Message-ID: <4413AA19.7090101@fuse.net> Date: Sat, 11 Mar 2006 23:56:57 -0500 From: jawod Subject: Re: Safety ground versus RF ground for a 2nd Floor shack References: <26f31$44110069$42a1bfc2$15706@FUSE.NET> jawod wrote: > I know this has been addressed on the group before but I remain confused. > > I will string a dipole in the trees. The coax shield will be earth > grounded, as well as the balun and lightening arrestor. > > Now, in the 2nd floor shack, I've read that running a ground line from > equipment 15 feet or more (in this case) to an earth ground will bring > RF into the shack and be a potent source for TVI, etc. > > My choice, then, is to use the ground on the mains. > > Given that the shield is earth grounded on the antenna and the equipment > is grounded to the mains, isn't this a good scenario for ground loop? > > Seems like a catch-22. > > My own gut says safety first, lower risk of RF issues after-the-fact by > ? what ? > > I remember suggestions of coiling the ground wire in an RF choke, > multiple ground lines of various lenghts to mess with harmonics. Ferrite > beads? Chicken blood and a black cat? > > John Reading the two responses so far...I'll get my advice elsewhere. Typical internet group response...mildly insulting and of no direct value. I first have to know what ground means? Whatever. Imaginary numbers apparently require imaginary minds. Article: 222123 of rec.radio.amateur.antenna From: Roy Lewallen Subject: Re: Soil dielectric constand and conductivity for East Texas Date: Sat, 11 Mar 2006 21:29:40 -0800 Message-ID: <1217ce8c8v1jpbe@corp.supernews.com> References: <6kf8e3-hhc.ln1@p400bob.personal.cox.net> <1142045725.211081.71000@u72g2000cwu.googlegroups.com> <1216ev1fa39ak9a@corp.supernews.com> Frank wrote: > > Certainly, all valid points. I was more interested in actually doing > precise measurements, but considered it might improve my model accuracy. I > even thought of digging a hole to see how the soil varied. Doubt I would > have dug down 20 or 30 ft. Most of the ground here is clay, and then > probably bedrock, at this elevation of just over 4,000 ft ASL. Ansoft's > HFSS, or CST, could probably handle an accurate, stratified, ground model. Do a web search for "OWL" (qualifying it with ground conductivity-related terms to cut down the references to the bird and other contexts). I believe it stands for "open wire line", and the last I heard, was the standard way of measuring RF ground conductivity. It involves a buried open wire line, but that's about all I know about it. There's certainly nothing wrong with learning to measure ground characteristics as an educational process. No matter what seemingly useless learning exercise I undertake, I ultimately learn many other things from it. By all means, go for it. I'd love to see some results from one of the good field solving programs for stratified grounds, even something contrived, and even a simple vertical with buried or elevated ground system. What I'd like to know is whether there really is a single value you could assign to a single homogeneous ground and get the same results. I suspect not, but have no proof one way or the other. Roy Lewallen, W7EL Article: 222124 of rec.radio.amateur.antenna From: "Reg Edwards" Subject: Radiation Resistance Date: Sun, 12 Mar 2006 09:53:29 +0000 (UTC) Message-ID: I am not trolling. What I want to know is the radiation resistance, referred to the base, of a short vertical wire above a perfect ground, the current in the wire being assumed uniformly distributed. The radiation resistance at the base is in the form of - C * Square( Length / Lambda ) where Length is the physical length or height of the wire and Lambda is the free-space wavelength. What is the value of the constant C ? Thank you. ---- Reg. Article: 222125 of rec.radio.amateur.antenna From: "Reg Edwards" Subject: Re: Soil dielectric constand and conductivity for East Texas Date: Sun, 12 Mar 2006 10:13:41 +0000 (UTC) Message-ID: References: <6kf8e3-hhc.ln1@p400bob.personal.cox.net> <1142045725.211081.71000@u72g2000cwu.googlegroups.com> <1216ev1fa39ak9a@corp.supernews.com> <1217ce8c8v1jpbe@corp.supernews.com> There's no need to ridicule measurements of soil resistivity just because at a deeper layer there is a strata of different resistivity. Any information is far better than complete ignorance. Roy, you are just displaying your knowledge of geology. Obviously, in practice it is the resistivity of the top layer which predominates anyway. ---- Reg. Article: 222126 of rec.radio.amateur.antenna From: Roy Lewallen Subject: Re: Radiation Resistance Date: Sun, 12 Mar 2006 03:16:40 -0800 Message-ID: <12180orrngmfn42@corp.supernews.com> References: C = 160 * pi^2 ~ 1579. This is exactly 4 times the radiation resistance of a short dipole with linear current distribution (i.e., one without a top hat), since the average current is twice the amount for the same radiated power. Of course, this assumes an infinitely thin wire. Any real wire will have a higher radiation resistance than this. Roy Lewallen, W7EL Reg Edwards wrote: > I am not trolling. > > What I want to know is the radiation resistance, referred to the base, > of a short vertical wire above a perfect ground, the current in the > wire being assumed uniformly distributed. > > The radiation resistance at the base is in the form of - > > C * Square( Length / Lambda ) > > where Length is the physical length or height of the wire and Lambda > is the free-space wavelength. > > What is the value of the constant C ? > > Thank you. > ---- > Reg. > > Article: 222127 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Radiation Resistance References: Message-ID: Date: Sun, 12 Mar 2006 14:13:05 GMT Reg Edwards wrote: > I am not trolling. > > What I want to know is the radiation resistance, referred to the base, > of a short vertical wire above a perfect ground, the current in the > wire being assumed uniformly distributed. > > The radiation resistance at the base is in the form of - > > C * Square( Length / Lambda ) > > where Length is the physical length or height of the wire and Lambda > is the free-space wavelength. > > What is the value of the constant C ? Reg, I believe it would be 10*pi^2 = 98.7, half of the value of a small dipole. Balanis gives a dipole a very thorough treatment and then says the monopole is half of those values. His constant in the value of radiation resistance for a short dipole is 20*pi^2. Kraus rounds that constant off to 200. That value assumes the short dipole is not infinitessimal and has a linear standing wave current distribution. That constant doesn't seem to need to be a very exact value. -- 73, Cecil http://www.qsl.net/w5dxp Article: 222128 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Radiation Resistance References: <12180orrngmfn42@corp.supernews.com> Message-ID: Date: Sun, 12 Mar 2006 14:21:00 GMT Roy Lewallen wrote: > C = 160 * pi^2 ~ 1579. > > This is exactly 4 times the radiation resistance of a short dipole with > linear current distribution (i.e., one without a top hat), since the > average current is twice the amount for the same radiated power. Since the resistance is inversely proportional to the current, shouldn't you have divided by 4 instead of multiplying by 4? -- 73, Cecil http://www.qsl.net/w5dxp Article: 222129 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Current through coils References: <1142043207.752336.206250@j52g2000cwj.googlegroups.com> <28826-4412519C-544@storefull-3255.bay.webtv.net> <1142073802.408256.64360@i40g2000cwc.googlegroups.com> <8_CQf.55899$Jd.1369@newssvr25.news.prodigy.net> <1216e3dskf72sa3@corp.supernews.com> <1142119851.274292.127420@j33g2000cwa.googlegroups.com> <1142162882.986318.46180@j52g2000cwj.googlegroups.com> Message-ID: Date: Sun, 12 Mar 2006 15:50:46 GMT w8ji@akorn.net wrote: > When I connected a > 10 foot RG-8X jumper, time delay was about 13.5 nS. Let's take a look at the measurement results. That 13.5 nS delay through the coax would make that piece of RG-8X 1/4WL self-resonant at ~18.5 MHz, higher than the specified 16 MHz self-resonant frequency for the coil. So the laws of physics would dictate that the delay through the coil cannot be less than the delay through that piece of coax. By definition, the physical meaning of that piece of coax being 1/4WL self-resonant at 18.5 MHz is that it takes 1/2 of a cycle in time for the forward wave to make a round trip to the end of the coax and back. 1/2WL of a cycle at 18.5 MHz is 27 nS. So the one- way delay through the coax is 1/2 of 27 or 13.5 nS. By definition, the physical meaning of that 10" coil being 1/4WL self-resonant at 16 MHz is that it takes 1/2 of a cycle in time for the forward wave to make a round trip to the end of the coil and back. 1/2 of a cycle at 16 MHz is 31 nS. So the one-way delay through that coil is 1/2 of 31 or 16.5 nS. The 1/4WL self-resonance point *IS* a measure of the delay through the coil just as it is a measure of the delay through a piece of transmission line. If the coil is indeed 1/4WL self-resonant at 16 MHz, the one-way delay through the coil is *already known* to be 16.5 nS and that is what should have been measured. The fact that the *known value* of the delay through the coil was not measured runs up a red flag and is technical proof that something was amiss with the reported results. -- 73, Cecil http://www.qsl.net/w5dxp Article: 222130 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Radiation Resistance References: <12180orrngmfn42@corp.supernews.com> <1142177866.861811.167300@z34g2000cwc.googlegroups.com> Message-ID: <0YXQf.38102$_S7.31145@newssvr14.news.prodigy.com> Date: Sun, 12 Mar 2006 16:25:32 GMT w8ji@akorn.net wrote: > Cecil's answer is not correct, but I'm sure you figured that out on > your own. Silly me, I was assuming the length of the monopole was assumed to be 1/2 the length of the dipole. -- 73, Cecil http://www.qsl.net/w5dxp Article: 222131 of rec.radio.amateur.antenna Date: Sun, 12 Mar 2006 18:00:49 +0100 From: paul Subject: Re: Concord,ca Police Department gives people tickets that have References: <1141922578.317968.87630@u72g2000cwu.googlegroups.com> Message-ID: <441453c3_2@news.bluewin.ch> blackhca@hotmail.com wrote: > Concord,ca Police Department Officer... This is only the work of a troll, google >"Ron Turner" Concord Police< and have a look at his mayhem. Article: 222132 of rec.radio.amateur.antenna From: Bob Subject: Re: Loop In Coax Help Prevent Lightning Induced Surges ? References: Message-ID: Date: Sun, 12 Mar 2006 17:15:02 GMT All the grounding info I have seen mentions no sharp bends, or any bends if you can help it when bonding tower legs, etc to ground rods or ground rings as it raises the impedance to the ground connection. I can see a loop in the coax being beneficial as a supplement to a ground system, but definitely not as the only precaution. It takes a well designed lightning ground system to take a direct hit without any damage and I have never seen one in a residential setting. I know several mountain top repeater sites that take hits all the time with no apparent damage but the entire site including the building, tower and electrical system were designed from the start with lightning in mind. Bob Robert11 wrote: > Hello: > > Anyone have any thoughts on (hopefully not experiences) whether putting a > loop of, e.g. 1 foot in diameter, > on a coax run from an outdoor receive-only antenna has any merit as far as > helping any emf lightning induced pulses from traveling into a house ? > > Have heard about this, but it's hard to believe it would actually do > anything in practice. > But,... ? > > B. > > Article: 222133 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Current through coils References: <1142043207.752336.206250@j52g2000cwj.googlegroups.com> <28826-4412519C-544@storefull-3255.bay.webtv.net> <1142073802.408256.64360@i40g2000cwc.googlegroups.com> <8_CQf.55899$Jd.1369@newssvr25.news.prodigy.net> <1216e3dskf72sa3@corp.supernews.com> <1142119851.274292.127420@j33g2000cwa.googlegroups.com> <1142162882.986318.46180@j52g2000cwj.googlegroups.com> Message-ID: Date: Sun, 12 Mar 2006 17:51:47 GMT John Popelish wrote: > Thanks much. This helps me to visualize your method in a much more > complete way. I think a photo of the test apparatus would make a fine > addition to your web page documenting this result. I am especially > interested on how all this stuff was arrayed in space during the test. John, would you agree or disagree with me that for a well-designed coil, the delay through the coil is fixed by the laws of physics as 1/4WL on the self- resonant frequency? If the self-resonant frequency of a well-designed coil is measured at 16 MHz, then the delay through the coil is 90 degrees at 16 MHz and therefore equal to 15.625 nS. Using the self-resonant frequency to determine the delay is an easy and accurate way to measure that delay. If the delay through the coil, measured at 1/4 the self-resonant frequency, is appreciably different >from the 15.6 nS measured at 16m, then the measurement contains an error. Agree/disagree? -- 73, Cecil http://www.qsl.net/w5dxp Article: 222134 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Current through coils References: <1142043207.752336.206250@j52g2000cwj.googlegroups.com> <28826-4412519C-544@storefull-3255.bay.webtv.net> <1142073802.408256.64360@i40g2000cwc.googlegroups.com> <8_CQf.55899$Jd.1369@newssvr25.news.prodigy.net> <1216e3dskf72sa3@corp.supernews.com> <1142119851.274292.127420@j33g2000cwa.googlegroups.com> <1142162882.986318.46180@j52g2000cwj.googlegroups.com> Message-ID: Date: Sun, 12 Mar 2006 18:13:30 GMT w8ji@akorn.net wrote: > Since all of my data agrees with data made a few years ago by a > different person using a different method with different equipment, and > since it agrees with reference material I have, I don't see any reason > to treat it like cutting edge results. You've probably hit the nail right on the head there, Tom. If your results agree with Roy's then you were again more than likely measuring standing-wave current and therefore gained nothing by making those measurements. How do you explain a well-designed coil exhibiting a measured delay of 15.6 nS at 16 MHz and a measured delay of 3 nS at 4 MHz? Don't you realize that is an impossibility according to the laws of physics? If the coil is well-designed at 16 MHz, it would also be well-designed at 4 MHz and exhibit very close to the same delay at both of those frequencies. Do you really think the delay changed by 81% between those two frequencies? Build yourself an SWR meter calibrated for the Z0 of that coil. Measure the SWR in your coil circuit. I'll bet it will be nearly infinite. Seems you are guilty of presupposing the proof again. -- 73, Cecil http://www.qsl.net/w5dxp Article: 222135 of rec.radio.amateur.antenna From: richardharrison@webtv.net (Richard Harrison) Subject: Re: Radiation Resistance Date: Sun, 12 Mar 2006 12:14:43 -0600 Message-ID: <23728-44146513-657@storefull-3254.bay.webtv.net> References: Reg wrote: "What is the value of the constant C?" 395 It is found on page 137 of Kraus` 1950 edition of "Antennas". Best regards, Richard Harrison, KB5WZI Article: 222136 of rec.radio.amateur.antenna From: John Ferrell Subject: Re: Description of W9INN 40/80 dipole Message-ID: References: Date: Sun, 12 Mar 2006 19:04:17 GMT Thanks for the description! It sounds like a design worth copying. On Sun, 12 Mar 2006 02:04:52 GMT, "Dick, AA5VU" wrote: >In article , > John Ferrell wrote: > >> I am glad to hear it now meets your expectations. I still have not >> found a diagram of your antenna, but I did find this very good artical >> on SWR: >> http://www.qsl.net/k2hq/swr.htm#PART%201 > >John, > >If you recall the old W9INN ads in QST you he has a 40/80 dipole. It >was full size 40 meter dipole with what I remember he called a resister >(that was really a coil) and about a 9 foot length of wire past the coil >for the 80 meter antenna. It was fed with coax to a center insulator. >Bill did not believe in baluns. > >I modified the antenna by two sets of wires. One for 10 MHz and the >other for 18 MHz. The 18 MHz seems to be resonant for 6 meters and the >whole mess works on 24 MHz as well. > >I did not see it on the K2HG web page > >73, Dick AA5VU John Ferrell W8CCW Article: 222137 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Radiation Resistance References: Message-ID: Date: Sun, 12 Mar 2006 19:53:49 GMT Cecil Moore wrote: > Reg, I believe it would be 10*pi^2 = 98.7, half of the > value of a small dipole. My bad. I falsely assumed that the length in the monopole equation was 1/2 the length in the dipole equation. Another senior moment. -- 73, Cecil http://www.qsl.net/w5dxp Article: 222138 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Radiation Resistance References: <23728-44146513-657@storefull-3254.bay.webtv.net> <1142193006.348265.71290@v46g2000cwv.googlegroups.com> Message-ID: Date: Sun, 12 Mar 2006 20:03:01 GMT w8ji@akorn.net wrote: > For a monopole with uniform current, C=1580 > For a monopole with triangular current C= 395 > > Radiation resistance is four times greater when the antenna has uniform > current. Reg didn't say "uniform current". He said "uniformly distributed current". A triangular current wave is uniformly distributed, i.e. it has a linear taper. Seem to me we need to find out what Reg meant by "uniformly distributed current". I thought he meant uniformly triangularly distributed. I think Richard thought the same thing. -- 73, Cecil http://www.qsl.net/w5dxp Article: 222139 of rec.radio.amateur.antenna From: Owen Duffy Subject: Re: Radiation Resistance Message-ID: References: <23728-44146513-657@storefull-3254.bay.webtv.net> Date: Sun, 12 Mar 2006 20:19:07 GMT On Sun, 12 Mar 2006 12:14:43 -0600, richardharrison@webtv.net (Richard Harrison) wrote: >Reg wrote: >"What is the value of the constant C?" > >395 > >It is found on page 137 of Kraus` 1950 edition of "Antennas". > Is that for uniform current as Reg asked? Owen -- Article: 222140 of rec.radio.amateur.antenna From: "Frank's" Subject: NEC 4.1 Anomaly Message-ID: <%y%Qf.18908$Cp4.12850@edtnps90> Date: Sun, 12 Mar 2006 20:31:55 GMT Possibly I am doing something really dumb, but have not been able to figure it out. I have been trying to model an inductor in NEC. NEC2 runs ok. If I run NEC 4.1, single precision (NEC4S600), I get a disconnect of 55 micro-meters between segments 300 and 301 -- which is treated as an open circuit (>0.001 of a segment length at 44 micro-meters). Changing the number of segments, or the number of turns, by one, corrects the problem. Typically the segment end-points are within < 3 micro-meters. I have not identified all conditions when this occurs, but some combinations of segments, and turns, do produce a disconnect. I have not completely investigated NEC 4.1, double precision, but it does run the code below with no disconnect evident. 73, Frank CM Inductor Calculation (NEC 4.1) CE GH 1 300 15 12 6 6 0.02015 0.02015 0 GW 2 3 6 0 12 0 0 12 0.02015 GW 3 6 0 0 12 0 0 0 0.02015 GW 4 3 0 0 0 6 0 0 0.02015 GS 0 0 0.025400 GE 0 EX 0 3 3 00 1 0 FR 0 5 0 0 3.7 0.02 LD 5 1 1 312 5.7001E7 RP 0 181 1 1000 -90 90 1.00000 1.00000 EN Article: 222141 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Radiation Resistance References: <23728-44146513-657@storefull-3254.bay.webtv.net> Message-ID: Date: Sun, 12 Mar 2006 20:46:21 GMT Owen Duffy wrote: > Is that for uniform current as Reg asked? Reg asked for "uniformly distributed current". I took that to mean having a constant slope. Wonder what Reg really meant? -- 73, Cecil http://www.qsl.net/w5dxp Article: 222142 of rec.radio.amateur.antenna From: richardharrison@webtv.net (Richard Harrison) Subject: Re: Radiation Resistance Date: Sun, 12 Mar 2006 14:40:36 -0600 Message-ID: <23728-44148744-675@storefull-3254.bay.webtv.net> References: <1142193006.348265.71290@v46g2000cwv.googlegroups.com> Tom, W8JI wrote: "You didn`t read something correctly." OK, here is the arithmetic. Radiation Resistance of a Short Electric Dipole: RR = 80 pi squared (L/lambda)squared Constant = 80 (8.97) = 790 But a short monopole has 1/2 the resistance of a short dipole. 790 / 2 = 395 All Reg asked for was the constant. Best regards, Richard Harrison, KB5WZI Article: 222143 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Current through coils References: <1142043207.752336.206250@j52g2000cwj.googlegroups.com> <28826-4412519C-544@storefull-3255.bay.webtv.net> <1142073802.408256.64360@i40g2000cwc.googlegroups.com> <8_CQf.55899$Jd.1369@newssvr25.news.prodigy.net> <1216e3dskf72sa3@corp.supernews.com> <1142119851.274292.127420@j33g2000cwa.googlegroups.com> <1142162882.986318.46180@j52g2000cwj.googlegroups.com> <4a-dnWqZ766NGonZnZ2dnUVZ_vidnZ2d@adelphia.com> Message-ID: Date: Sun, 12 Mar 2006 20:57:55 GMT John Popelish wrote: > I am still having a > bit of trouble visualizing how the coil was instrumented and terminated > to get this result. I am also a beginner when it comes to S parameters. I think Tom did what I did the other night. I hooked the coil across my IC-756PRO's output, used minimum power, and tried to supply 4 MHz power to the 4+j1250 ohm coil that I have. It naturally rejected (reflected) virtually all of that power. I found, as Tom did, that the standing wave current at both ends has virtually identical phases but that is already known. The delay through the coil simply cannot be tested in that test arrangement. Tom just repeated Roy's experiment of a few years ago and obtained the same meaningless results. So did I so I didn't even bother to report them. > My reservation with you and few others is your emotional > investment in being correct. It makes your opinions less > trustworthy. Whoa there, I just made a mental blunder about radiation resistance and readily admitted it. My emotional investment is in fighting falsehoods, myths, and old wives' tales. That's all. The test method for determining the delay through a piece of transmission line or a coil is the same as it has been for more than a century. Find the 1/4WL self-resonant point and calculate the delay. Other methods, resulting in far different results, are obviously invalid. -- 73, Cecil http://www.qsl.net/w5dxp Article: 222144 of rec.radio.amateur.antenna From: Owen Duffy Subject: Re: Radiation Resistance Message-ID: References: <23728-44146513-657@storefull-3254.bay.webtv.net> Date: Sun, 12 Mar 2006 21:14:05 GMT On Sun, 12 Mar 2006 20:46:21 GMT, Cecil Moore wrote: >Owen Duffy wrote: >> Is that for uniform current as Reg asked? > >Reg asked for "uniformly distributed current". I took >that to mean having a constant slope. Wonder what Reg >really meant? In the context of his use, I think the most probably reasonable interpretation of Reg's words is that the current is uniform at all points on the radiator. Yes, it does also have a constant slope (of zero), so you will ba able to argue a correct interpetation either way, even if the results are different. It was interesting how many different interpretations were made, and then how many different answers to such a simple questions, even a text book incorrectly quoted (yes, subject to your interpretation of Richard's interpretation of what was in Reg's mind. Reg will no doubt chuckle when he wakes in the morning. Owen -- Article: 222145 of rec.radio.amateur.antenna From: richardharrison@webtv.net (Richard Harrison) Subject: Re: Radiation Resistance Date: Sun, 12 Mar 2006 15:06:15 -0600 Message-ID: <23728-44148D47-676@storefull-3254.bay.webtv.net> References: Owen Duffy wrote: "Is that for uniform current as Reg asked?" Reg described a short vertical wire above a perfect ground. Without a capacitive hat or some such device, you have an open circuit at the tip of the antenna (zero current) and a finite current at the driven end of the wire. How would the current be uniform end to end? Best regards, Richard Harrison, KB5WZI Article: 222146 of rec.radio.amateur.antenna From: Gene Fuller Subject: Re: Radiation Resistance References: <1142193006.348265.71290@v46g2000cwv.googlegroups.com> <23728-44148744-675@storefull-3254.bay.webtv.net> Message-ID: Date: Sun, 12 Mar 2006 21:21:45 GMT Richard, Your calculation is OK as far as it goes. However, you overlooked the fact that "L" is different for the dipole and the monopole. The monopole has 1/2 the length of the dipole or 1/4 the length squared. The coefficient Reg asked for is therefore 4 times the number you quoted. 73, Gene W4SZ Richard Harrison wrote: > Tom, W8JI wrote: > "You didn`t read something correctly." > > OK, here is the arithmetic. > > Radiation Resistance of a Short Electric Dipole: > > RR = 80 pi squared (L/lambda)squared > > Constant = 80 (8.97) = 790 > > But a short monopole has 1/2 the resistance of a short dipole. > > 790 / 2 = 395 > > All Reg asked for was the constant. > > Best regards, Richard Harrison, KB5WZI > Article: 222147 of rec.radio.amateur.antenna From: Owen Duffy Subject: Re: Radiation Resistance Message-ID: References: <23728-44148D47-676@storefull-3254.bay.webtv.net> Date: Sun, 12 Mar 2006 21:31:06 GMT On Sun, 12 Mar 2006 15:06:15 -0600, richardharrison@webtv.net (Richard Harrison) wrote: >Owen Duffy wrote: >"Is that for uniform current as Reg asked?" > >Reg described a short vertical wire above a perfect ground. > >Without a capacitive hat or some such device, you have an open circuit >at the tip of the antenna (zero current) and a finite current at the >driven end of the wire. How would the current be uniform end to end? That is *your* logic, and on the basis of it, you have chosen to ignore part of the original question, the explicit statement "the current in the wire being assumed uniformly distributed", without qualifying your one word answer. Owen -- Article: 222148 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Radiation Resistance References: <23728-44146513-657@storefull-3254.bay.webtv.net> Message-ID: <441Rf.56121$Jd.47791@newssvr25.news.prodigy.net> Date: Sun, 12 Mar 2006 22:15:28 GMT Owen Duffy wrote: > Yes, it does also have a constant slope (of zero), so you will ba able > to argue a correct interpetation either way, even if the results are > different. OK, I will change my statement to a "constant non-zero slope". I really think that what's Reg meant but obviously only Reg's opinion is important on that matter. :-) > Reg will no doubt > chuckle when he wakes in the morning. :-) When I chuckle with a hangover, it hurts. :-) -- 73, Cecil http://www.qsl.net/w5dxp Article: 222149 of rec.radio.amateur.antenna From: Cecil Moore Subject: Re: Current through coils References: <1142043207.752336.206250@j52g2000cwj.googlegroups.com> <28826-4412519C-544@storefull-3255.bay.webtv.net> <1142073802.408256.64360@i40g2000cwc.googlegroups.com> <8_CQf.55899$Jd.1369@newssvr25.news.prodigy.net> <1216e3dskf72sa3@corp.supernews.com> <1142119851.274292.127420@j33g2000cwa.googlegroups.com> <1142162882.986318.46180@j52g2000cwj.googlegroups.com> <4a-dnWqZ766NGonZnZ2dnUVZ_vidnZ2d@adelphia.com> Message-ID: Date: Sun, 12 Mar 2006 22:40:17 GMT John Popelish wrote: > But the goal of such "fights" should be altering other's opinions. How's > that been working out for you? ;-) That's not my goal at all, John. My goal is to discuss the technical facts. I really don't care if anyone "alters their opinions" or not. That has been a personality characteristic since my early days. My sister just remarked on that same fact a few days ago. She said, "You have never cared what other people think about you." It wasn't a criticism, just an observation. We may understand the results of Tom's latest measurement by considering the following: 50 ohm source===1 WL 50 ohm lossless coax===8+j2500 load Since the transmission line is lossless, this doesn't change anything except for the additional one cycle delay through the line. What's the system SWR? I get 16000:1. I asked Tom to measure the currents in the absence of a high SWR and he takes his measurements in a 16000:1 SWR environment. How well do you think he honored my request for an SWR of 1:1? Shucks, he only missed it by 1,600,000%. :-) There is essentially no net energy flow in the above network. Why are we suprised to measure equal standing wave currents on each side of the coil? It wouldn't have surprised me if Tom had measured *zero* phase shift just like the lumped-circuit model predicts. The traveling- wave delay through a coil simply cannot be measured using Tom's methods. -- 73, Cecil http://www.qsl.net/w5dxp Article: 222150 of rec.radio.amateur.antenna From: "Bill Turner" Subject: Re: Description of W9INN 40/80 dipole References: Message-ID: <4414a523_1@newsfeed.slurp.net> Date: 12 Mar 2006 17:48:03 -0500 ORIGINAL MESSAGE: Dick, AA5VU wrote: > It > was full size 40 meter dipole with what I remember he called a > resister (that was really a coil) ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ The word was "resonactor". I have one of his antennas and it works fine. I have not examined the resonactor in detail, but I believe it is just an inductor which is carefully wound to be self-resonant at the desired frequency, thereby eliminating the need for a separate capacitor to resonate it. A clever idea, since eliminating the separate capacitor easily allows full legal power without the expense of a very high voltage capacitor. W9INN's trap dipoles are the only ones I know of which advertise full legal power handling, and that's why I purchased one. I've been running full power RTTY on mine for five years with no problems. Since I purchased mine there may have been other full power trap dipoles come on the market. If anyone knows of one, please reply. I'm always curious about such things. Bill, W6WRT Article: 222151 of rec.radio.amateur.antenna From: "Tom Donaly" Subject: Re: Current through coils References: <28826-4412519C-544@storefull-3255.bay.webtv.net> <1142073802.408256.64360@i40g2000cwc.googlegroups.com> <8_CQf.55899$Jd.1369@newssvr25.news.prodigy.net> <1216e3dskf72sa3@corp.supernews.com> <1bj7129btemua297vutapmnrhc1kn4l73f@4ax.com> Message-ID: <0M1Rf.53582$H71.9935@newssvr13.news.prodigy.com> Date: Sun, 12 Mar 2006 23:02:20 GMT Richard Clark wrote: > On Sun, 12 Mar 2006 02:29:51 GMT, Cecil Moore wrote: > > >>Tom Donaly wrote: >> >>>Cecil, have you ever read the book _Don Quixote_, by Cervantes? >>>There's a character in there you remind me of. >> >>Tom, please don't tell me that you also believe that a distributed- >>network analysis using wave reflection theory is "gobbledygook". > > > Hmm, Tom, let me guess - Dulcinea. The object of Quixote's attention > who never appears, but is always dreamt about. Hi Richard, that sounds like Cecil's theory, which he's always ready to defend with his strong right arm. I can't believe all the fuss he's made over something as trivial as a loading coil. 73, Tom Donaly, KA6RUH Article: 222152 of rec.radio.amateur.antenna From: "Tom Donaly" Subject: Re: Current through coils References: <1142043207.752336.206250@j52g2000cwj.googlegroups.com> <28826-4412519C-544@storefull-3255.bay.webtv.net> <1142073802.408256.64360@i40g2000cwc.googlegroups.com> <8_CQf.55899$Jd.1369@newssvr25.news.prodigy.net> <1216e3dskf72sa3@corp.supernews.com> Message-ID: <6Q1Rf.53583$H71.6987@newssvr13.news.prodigy.com> Date: Sun, 12 Mar 2006 23:06:42 GMT Cecil Moore wrote: > Tom Donaly wrote: > >> Cecil, have you ever read the book _Don Quixote_, by Cervantes? >> There's a character in there you remind me of. > > > Tom, please don't tell me that you also believe that a distributed- > network analysis using wave reflection theory is "gobbledygook". It is when the components are small enough in relation to a wavelength that you don't have to use "a distributed-network analysis". Actually, the way you've been talking about it, lately, it sounds more like word salad than gobbledygook. 73, Tom Donaly, KA6RUH Article: 222153 of rec.radio.amateur.antenna From: Roy Lewallen Subject: Re: Radiation Resistance Date: Sun, 12 Mar 2006 15:44:05 -0800 Message-ID: <1219ci9lkjprr1d@corp.supernews.com> References: <23728-44148D47-676@storefull-3254.bay.webtv.net> Richard Harrison wrote: > Owen Duffy wrote: > "Is that for uniform current as Reg asked?" > > Reg described a short vertical wire above a perfect ground. > > Without a capacitive hat or some such device, you have an open circuit > at the tip of the antenna (zero current) and a finite current at the > driven end of the wire. How would the current be uniform end to end? For the answer to that, open your Kraus again, and go to the beginning of the chapter (5) you quoted from. It's explained in the first paragraph. There's even a picture, Fig. 5-1. Roy Lewallen, W7EL Article: 222154 of rec.radio.amateur.antenna From: Roy Lewallen Subject: Re: Radiation Resistance Date: Sun, 12 Mar 2006 15:45:57 -0800 Message-ID: <1219clp27lvpu79@corp.supernews.com> References: <1142193006.348265.71290@v46g2000cwv.googlegroups.com> <23728-44148744-675@storefull-3254.bay.webtv.net> Richard Harrison wrote: > Tom, W8JI wrote: > "You didn`t read something correctly." > > OK, here is the arithmetic. > > Radiation Resistance of a Short Electric Dipole: > > RR = 80 pi squared (L/lambda)squared > > Constant = 80 (8.97) = 790 > > But a short monopole has 1/2 the resistance of a short dipole. > > 790 / 2 = 395 > > All Reg asked for was the constant. > If you'll read more in the chapter of Kraus you're quoting, you'll notice that L is the length of the dipole, not the length of a monopole. Do the proper substitution and you'll get the correct answer. Roy Lewallen, W7EL