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Current across the antenna loading coil - from scratch
Ian White GM3SEK wrote:
Based entirely on what you yourself have written, I have told you that you don't understand something. Are the odds zero that it might be your misunderstanding? Please respond to this previous posting: The testx.EZ file has been renamed to: http://www.qsl.net/w5dxp/TravWave.EZ The testy.EZ file has been renamed to: http://www.qsl.net/w5dxp/StndWave.EZ The current reported by EZNEC for TravWave.EZ contains the term cos(kz+wt) It's a traveling wave current, clearly not the same as a standing wave current. The current reported by EZNEC for StndWave.EZ contains the terms cos(kz)*cos(wt) It's a standing wave current, clearly not the same as a traveling wave current. Current reported by EZNEC every 10% of wire #2 is presented in the following table. The currents are obviously very different. The phase of the traveling wave progresses from 0 to 90 deg in 90 deg of wire. The phase of the standing wave doesn't progress beyond 0.11 of of degree. % along current in current in wire #2 TravWave.EZ StndWave.EZ 0% 0.9998 at -0.99 deg 0.9996 at 0 deg 10% 0.9983 at -9.39 deg 0.9843 at -0.03 deg 20% 0.9969 at -18.23 deg 0.9454 at -0.05 deg 30% 0.9957 at -27.59 deg 0.8843 at -0.06 deg 40% 0.9949 at -35.96 deg 0.8023 at -0.08 deg 50% 0.9945 at -44.84 deg 0.7014 at -0.09 deg 60% 0.9945 at -54.20 deg 0.5840 at -0.09 deg 70% 0.9949 at -62.58 deg 0.4528 at -0.10 deg 80% 0.9956 at -71.43 deg 0.3110 at -0.11 deg 90% 0.9965 at -80.27 deg 0.1616 at -0.11 deg 100% 0.9976 at -89.14 deg 0.0061 at -0.11 deg Some say "current is current". EZNEC disagrees. When reflected waves are eliminated, EZNEC indeed does accurately report traveling wave current. EZNEC reports the current that is there, whether it is traveling wave current or standing wave current. -- 73, Cecil http://www.qsl.net/w5dxp |
Current across the antenna loading coil - from scratch
On Wed, 5 Apr 2006 19:51:45 -0500, "Richard Fry"
wrote: "Richard Clark"wrote Sounds like you have a problem following context. .... If you can find ANYTHING in my posts on this subject to support your statements, please quote them to the NG. What a tedious imposition to have to repeat correspondence, but if that is your price, then only one example in full: On Tue, 4 Apr 2006 12:11:20 -0500, "Richard Fry" wrote: The effective electrical length of a MW monople radiator determines its resonant frequencies, and that must include the velocity of propagation along the structure -- which is a function of the height AND width of the radiator (mainly), and the operating frequency. KYMN 118.60° tall 92.3 meters tall 1080 kHz http://www.fcc.gov/mb/audio/amq.html The FCC recitation of these facts is one such MW monopole radiator. We proceed to YOUR reference: "Antenna Engineering Handbook," 2nd edition (pub. 1984), by Johnson and Jasik specifically to YOUR point a function of the height AND width which is manifest in figure 4-4. If you cannot resolve that graph, and for others reading, it shows a family of curves constructed on the basis of A/D which is elsewhere described as Length over Diameter. For a radiator of 118.60° tall the only curve passing through zero reactance is assigned an A/D of 20. A is already known and is 118.60°. It then follows to satisfy the A/D of 20 drives the value of D to be 5.93° which for a wavelength of 277.8 meters works out to be a diameter of 4.58 meters (corrected from my computational error earlier). In EZNEC the thin wire model reveals a source Z of: Impedance = 97.63 + J 371.5 ohms which confirms against figure 4-4's example for an A/D=1000 I don't know the validity of forcing the radiator to the 4.58 meter specification, but EZNEC clearly shows that move drives out reactance with a source Z of: Impedance = 133.8 + J 78.91 ohms This, too, conforms to figures 4-3 and 4-4 to within acceptable limits of error. If that offends your sense of accuracy, we can take it outside. I see no need to proceed further along lines that clearly follow the precepts offered by J&J. Now, returning to the diameter that has been proven to be necessary to resonate this instance which you dismiss as "ridiculous examples," my comment about seeing very few towers that exhibit this magnitude of diameter (the size of my living room) still stands as unimpeached. Going further into your cavalier dismissal of "ridiculous examples" we find that there are a forest of very short antennas in service. My link provides so many in one frequency assignment that the force of numbers cannot be denied so simply, and certainly when lacking technical rebuttal. Those offered such as: WXNH 56.30° tall 540 kHz when run through the same exercise above (YOUR reference, YOUR claims) reveals a necessary A/D of LESS THAN 5. The simple math resounds with the implications of necessary diameter to resonate this through (YOUR claims YOUR quotes of): "The effective electrical length of a MW monopole radiator determines its resonant frequencies, and that must include the velocity of propagation along the structure -- which is a function of the height AND width of the radiator (mainly), and the operating frequency." For a wavelength of 555.6 meters, that A/D resolves D to a value of 111 meters (and this arbitrary selection of A/D=5 is NOT the necessary value it is less) or the 364 feet. I see no reason to impeach J&J by attempting this with EZNEC for a result that is so obviously absurd in the real world to achieve. This absurdity reveals that it takes much more than these intellectual shenanigans of height AND (YOUR emphasis) width to resonate a short antenna. Please note THIS context which has been part and parcel to these threads for more than 1000 pieces of correspondence. Hence, the suite of recited example antennas clearly exhibit an expressed height, in degrees, that are strictly an expression of their physical height in terms of wavelength, and have nothing to do with their being resonant OR non-resonant. It is equally clear that in their service, there have been means made to resonate them, and that does not impact their height description either. 73's Richard Clark, KB7QHC p.s. No, from your posts IMO it is YOU who has a problem with your reading comprehension, and/or possibly your professional integrity. This is an amateur forum, and I don't trade on my professional credentials to retail them as proof. Reading comprehension is best left to the rest to evaluate; and as many express confusion, or difficulty with my writing, none have challenged my data. I can live with their confusion, and justify that with a quote from Dr. Samuel Johnson, courtesy of his biographer James Boswell: Johnson having argued for some time with a pertinacious gentleman; his opponent, who had talked in a very puzzling manner, happened to say, "I don't understand you, Sir" upon which Johnson observed, "Sir, I have found you an argument; but I am not obliged to find you an understanding." |
Current across the antenna loading coil - from scratch
Richard, Richard, Richard. Clark, that is. Shame on you. Get a grip.
Richard Fry's list simply showed that in the FCC listing, the length in degrees is calculated on the basis of freespace speed of light. In addition, he was pointing out that resonance is not at 90 degrees, calculated in that manner. THAT point is supported by other data. The FCC data didn't come into play with respect to that point. All that was obvious to me. Do you disagree that resonance of a monopole over a ground plane is for a length somewhat shorter than c/(4*f(resonance))? If you do, then let's have a discussion about THAT. Cheers, Tom |
Current across the antenna loading coil - from scratch
On 5 Apr 2006 21:05:43 -0700, "K7ITM" wrote:
Do you disagree that resonance of a monopole over a ground plane is for a length somewhat shorter than c/(4*f(resonance))? If you do, then let's have a discussion about THAT. Hi Tom, Do I disagree? Now, there's a classic line that too frequently litters these threads. I've offered many antennas that are spectacularly (considering their commercial application) shorter than quarterwave (the same size, and longer too). These shorter antennas easily embody your comment above. Now what is the THAT that seems to bear discussing that I haven't already covered twice? Three times is not a charm. 73's Richard Clark, KB7QHC |
Current across the antenna loading coil - from scratch
"Richard Clark" wrote:
On Tue, 4 Apr 2006 12:11:20 -0500, "Richard Fry" wrote: The effective electrical length of a MW monople radiator determines its resonant frequencies, and that must include the velocity of propagation along the structure -- which is a function of the height AND width of the radiator (mainly), and the operating frequency. Now, returning to the diameter that has been proven to be necessary to resonate this instance which you dismiss as "ridiculous examples," my comment about seeing very few towers that exhibit this magnitude of diameter (the size of my living room) still stands as unimpeached. Going further into your cavalier dismissal of "ridiculous examples" we find that there are a forest of very short antennas in service. My link provides so many in one frequency assignment that the force of numbers cannot be denied so simply, and certainly when lacking technical rebuttal. Those offered such as WXNH 56.30° tall 540 kHz when run through the same exercise above (YOUR reference, YOUR claims) reveals a necessary A/D of LESS THAN 5. The simple math resounds with the implications of necessary diameter to resonate this... ____________ You have seized and fixated on a concept I did not generate, ie, that AM broadcast antennas all need to be SELF-resonant, and that their L-D ratio is the way to achieve that. Anyone referencing my statement quoted above in this post, and thinking its does so has problems with reading comprehension. Why don't you just accept this reality, and move on? RF |
Current across the antenna loading coil - from scratch
On Thu, 6 Apr 2006 06:30:50 -0500, "Richard Fry"
wrote: Why don't you just accept this reality, and move on? Reality? Now there's a cornpone cliché. It should take little imagination (dull intelligence rather), once reading the topic line these postings fall under, to accept the thread of continuity has been about 1. Loads in 2. very short antennas whose 3. height has been expressed in degrees when 4. resonant. There is absolutely no difference in outcome, be it an AM antenna, or a Hamstick in the back yard. 73's Richard Clark, KB7QHC |
Current across the antenna loading coil - from scratch
Ian White GM3SEK wrote:
Based entirely on what you yourself have written, I have told you that you don't understand something. Unless you can prove you are omniscient, Ian, the problem could possibly be with your misunderstanding of something, not mine. % along current in current in wire #2 TravWave.EZ StndWave.EZ 0.28% 0.9998 at -0.99 deg 0.9996 at 0 deg 9.72% 0.9983 at -9.39 deg 0.9843 at -0.03 deg 19.7% 0.9969 at -18.23 deg 0.9454 at -0.05 deg 30.3% 0.9957 at -27.59 deg 0.8843 at -0.06 deg 39.7% 0.9949 at -35.96 deg 0.8023 at -0.08 deg 49.7% 0.9945 at -44.84 deg 0.7014 at -0.09 deg 60.3% 0.9945 at -54.20 deg 0.5840 at -0.09 deg 69.7% 0.9949 at -62.58 deg 0.4528 at -0.10 deg 79.7% 0.9956 at -71.43 deg 0.3110 at -0.11 deg 89.7% 0.9965 at -80.27 deg 0.1616 at -0.11 deg 99.7% 0.9976 at -89.14 deg 0.0061 at -0.11 deg My EZNEC data posting proves that EZNEC correctly predicts the differences in the traveling wave current and the standing wave current. I'm building a new web page around those results. I have graphed the EZNEC results and they are available at: http://www.qsl.net/w5dxp/travstnd.GIF Please note that the traveling wave magnitude looks like the standing wave phase and the traveling wave phase looks like the standing wave magnitude. Anyone who maintains that there is no difference between a traveling wave current and a standing wave current should take a long close look. The corresponding EZNEC files are available at: http://www.qsl.net/w5dxp/TravWave.EZ http://www.qsl.net/w5dxp/StndWave.EZ -- 73, Cecil http://www.qsl.net/w5dxp |
Current across the antenna loading coil - from scratch
W8JI and other unbelievers that antenna and loading coils can not be
expressed in electrical degrees, can find another example in ON4UN's Low Band DXing book, 4th edition, page 9-47, Fig 9-58, showing loaded vertical with mast being 40 deg. 59.6 ft. long, loading coil of 144 uH taking (replacing radiator of) 40 deg and whip of 10 deg and 14.9 ft long, for overall 90 deg electrical and quarter wave resonant system. Soooo, to anyone outside of "equal current worshippers" it is obvious that coil is replacing 40 deg worth of radiator and it would drop equivalent amount of current across the coil that corresponds to the length of radiator that coil replaces, because rest of the "straight" radiator FORCES IT TO DO - because of standing wave and current. Such a heresy! Theeere is your sign! Yuri, K3BU/m |
Current across the antenna loading coil - from scratch
Yuri Blanarovich wrote: W8JI and other unbelievers that antenna and loading coils can not be expressed in electrical degrees, can find another example in ON4UN's Low Band DXing book, 4th edition, page 9-47, Fig 9-58, showing loaded vertical with mast being 40 deg. 59.6 ft. long, loading coil of 144 uH taking (replacing radiator of) 40 deg and whip of 10 deg and 14.9 ft long, for overall 90 deg electrical and quarter wave resonant system. Soooo, to anyone outside of "equal current worshippers" it is obvious that coil is replacing 40 deg worth of radiator and it would drop equivalent amount of current across the coil that corresponds to the length of radiator that coil replaces, because rest of the "straight" radiator FORCES IT TO DO - because of standing wave and current. That is not correct Yuri. Anything from a pure inductance to a very poor distributed inductor (like a linear loading or stub) can be used and all would have different characteristics. A pure inductance would have no current difference at each end. A good compact inductor would have negligible current difference at each end, only a long straight wire would act like the "missing antenna". One way to prove the coil does not replace missing length is to simply move the coil to a new location in a fixed height antenna. If the coil looked like 40 degrees, it would resonate the antenna no matter where it was installed. 73 Tom |
Current across the antenna loading coil - from scratch
On Thu, 6 Apr 2006 23:22:01 -0400, "Yuri Blanarovich"
wrote: it is obvious that coil is replacing 40 deg worth of radiator Hi Yuri, So obvious that you cannot express the accuracy necessary to resolve the "big picture." So obvious you cannot express the actual efficiency of having the coil there, or not having the coil there. So obvious that it is 40 degrees, that the previously unknown accuracy allows that to slip between 16.4 degrees and 63.6 degrees. So obvious that if you choose just the right number, then you can resonate on three bands with one coil. So obvious: who needs an antenna? What is not obvious is the name of your religion. for overall 90 deg electrical and quarter wave resonant system. Hence my recent correspondence has anticipated just this claim - but then that was as easy as shooting hunting partners in the face. 73's Richard Clark, KB7QHC |
Current across the antenna loading coil - from scratch
Another 'speriment occured to me, for those who think the coil current
MUST be different at the two ends by the amount corresponding to the antenna section it replaces: try making the antenna diameter large compared with the coil diameter, say two to four times the coil diameter, while maintaining the same lengths, and see what happens. I suppose you'll have to adjust the inductance of the coil, but keep its diameter and length the same. If the current at the ends of the coil remains nominally the same as with a thin antenna, then I'll say you're onto something. If on the other hand, the current becomes much more similar at the two ends of the coil, that will be evidence of a different effect--in fact the effect that I expect is actually accounting for the difference. Perhaps someone would like to try that in NEC2 or NEC4 and share the results, if nobody is actually up to building the antenna and measuring things. Cheers, Tom Tom, W8JI, wrote in Message-ID: .com: Yuri Blanarovich wrote: W8JI and other unbelievers that antenna and loading coils can not be expressed in electrical degrees, can find another example in ON4UN's Low Band DXing book, 4th edition, page 9-47, Fig 9-58, showing loaded vertical with mast being 40 deg. 59.6 ft. long, loading coil of 144 uH taking (replacing radiator of) 40 deg and whip of 10 deg and 14.9 ft long, for overall 90 deg electrical and quarter wave resonant system. Soooo, to anyone outside of "equal current worshippers" it is obvious that coil is replacing 40 deg worth of radiator and it would drop equivalent amount of current across the coil that corresponds to the length of radiator that coil replaces, because rest of the "straight" radiator FORCES IT TO DO - because of standing wave and current. That is not correct Yuri. Anything from a pure inductance to a very poor distributed inductor (like a linear loading or stub) can be used and all would have different characteristics. A pure inductance would have no current difference at each end. A good compact inductor would have negligible current difference at each end, only a long straight wire would act like the "missing antenna". One way to prove the coil does not replace missing length is to simply move the coil to a new location in a fixed height antenna. If the coil looked like 40 degrees, it would resonate the antenna no matter where it was installed. 73 Tom |
Current across the antenna loading coil - from scratch
Of course loading coils can be expressed in electrical degrees. But
extrapolating this to mean that a loading coil has the same properties as an antenna with the same number of "degrees" has no justification. Yuri's theory was shown to be false not only by many of the good technical arguments given here in this thread, but also by a careful measurement I made over a year ago. I built a 33 foot high vertical and loaded it at the bottom with a toroidal inductor to resonate it at 3.8 MHz. The coil "replaced" 33.4 electrical degrees of antenna. Yuri's theory predicts that the current at the top of the inductor should be 16.5% less than that at the bottom, with a phase shift of 33.4 degrees. What I measured was a current drop of 5.4% and no measurable phase shift across the inductor. Both the description of the setup and the detailed results were posted on this newsgroup on Nov. 11, 2003, with the subject title " Current in antenna loading coils controversy - new measurement". Anyone can find those postings with groups.google.com. Yuri's response, also on Nov. 11, 2003 was to complain about my methodology, declare that he was still right, and state "I will measure things myself, try to verify previous measurements and then come up with conclusions and 'theory'." On Nov. 12, 2003, he posted: "I will be making snap-on current probe, which will make it easier to slide along the element and observe the current without the disturbance to the antenna and will be a bit different over the thermocouple meters. Just need a bit more time." Well, it's been over a year now, and all I've seen is the same unsupported theory with no evidence to contradict the contrary evidence which has been presented. When a belief stays fixed in spite of both contradictory solid theory and measurements, it fits into the category of religion, not science. So it's appropriate that Yuri speaks in terms of an explanation being a "heresy". What's next, "good" and "evil" theories? Roy Lewallen, W7EL Yuri Blanarovich wrote: W8JI and other unbelievers that antenna and loading coils can not be expressed in electrical degrees, can find another example in ON4UN's Low Band DXing book, 4th edition, page 9-47, Fig 9-58, showing loaded vertical with mast being 40 deg. 59.6 ft. long, loading coil of 144 uH taking (replacing radiator of) 40 deg and whip of 10 deg and 14.9 ft long, for overall 90 deg electrical and quarter wave resonant system. Soooo, to anyone outside of "equal current worshippers" it is obvious that coil is replacing 40 deg worth of radiator and it would drop equivalent amount of current across the coil that corresponds to the length of radiator that coil replaces, because rest of the "straight" radiator FORCES IT TO DO - because of standing wave and current. Such a heresy! Theeere is your sign! Yuri, K3BU/m |
Current across the antenna loading coil - from scratch
K7ITM wrote:
Another 'speriment occured to me, for those who think the coil current MUST be different at the two ends by the amount corresponding to the antenna section it replaces: try making the antenna diameter large compared with the coil diameter, say two to four times the coil diameter, while maintaining the same lengths, and see what happens. I suppose you'll have to adjust the inductance of the coil, but keep its diameter and length the same. If the current at the ends of the coil remains nominally the same as with a thin antenna, then I'll say you're onto something. If on the other hand, the current becomes much more similar at the two ends of the coil, that will be evidence of a different effect--in fact the effect that I expect is actually accounting for the difference. Perhaps someone would like to try that in NEC2 or NEC4 and share the results, if nobody is actually up to building the antenna and measuring things. I'm afraid that the proponents of the alternative theories aren't subject to either modeling or measurement results. There's already ample theoretical, modeling, and measurement evidence to show that the theory is faulty; further efforts would be a waste of time. Roy Lewallen, W7EL |
Current across the antenna loading coil - from scratch
Cecil Moore wrote:
Ian White GM3SEK wrote: Based entirely on what you yourself have written, I have told you that you don't understand something. Unless you can prove you are omniscient, Ian, the problem could possibly be with your misunderstanding of something, not mine. It certainly *is* possible to make a correct analysis of a short coil-loaded antenna in terms of forward, reflected and standing waves of current. My objections are only about errors in Cecil's specific attempt to do it. This particular problem is a small hole in our jigsaw puzzle of human knowledge. It would certainly be worthwhile to craft a new piece, and to have the satisfaction seeing it fit exactly into place. But jigsaw puzzles have unbreakable rules: a new piece must fit EXACTLY into the gap that it fills; and everywhere around its edges, the picture MUST join up EXACTLY. If it fails to fit exactly and in every detail, then it isn't the right piece. All the surrounding pieces of existing knowledge about antenna engineering fit neatly together to make a solid picture. We can see the big picture, and that we're only trying to fill a very small gap. That big picture is made up from only a very few primary colors. They can blend together to give infinite hues and subtleties, but everything comes from mixing those same few primary colors which DO NOT CHANGE. The 'primary colors' of antenna engineering are a few fundamental physical facts that DO NOT CHANGE from one piece of the puzzle to the next. (Out at the far edges of the puzzle, the advances of 20th-century physics have shown that classical physics is part of an even bigger picture than we'd imagined - but in doing so they have confirmed where the rules of classical physics still CAN be applied. That includes the whole of electrical and electronic engineering, except for what happens inside semiconductor devices. Regarding antennas, Einstein's equations include and clarify Maxwell's equations, and quantify the margins of error in this area of classical physics. This confirms that antenna engineering indeed CAN be completely and accurately understood using classical physics, because the margins of error are too small to affect any practical observations.) Returning to this particular gap in the picture of antenna engineering, concerning short loaded antennas, we can see that it's only a small gap. It is surrounded by large areas of existing knowledge that interlock solidly and completely. That means we can be confident there will be nothing different or special happening inside that gap. When trying to fill any gap in our existing knowledge, that piece of advance information - that the same fundamentals will apply - is a tremendous help. Or it should be... the trouble starts when someone tries to ignore that fact, or worse still, tries to fight it. It is also important to note that there are already several other ways of thinking about loaded antennas that DO fit perfectly into the puzzle. There are many alternative ways to think about any particular piece, and as long as they fit with reality all around them, they are interchangeable. Cecil wants to try a method based on forward, reflected and standing waves, and that's just fine. As i said, I'm sure it can be done. The existing knowledge that such a theory must fit includes: what travelling and standing waves are; what electric current is; what inductance does; how real-life coils are different; and how things change when circuits become physically large enough to make electromagnetic coupling important (so we begin to call them antennas). But Cecil's new piece for the puzzle uses new and special definitions and properties for electric current, inductance, and travelling and standing waves - they are not the same as in all the surrounding pieces. To me, that is absolute proof that his new piece doesn't fit. He has bent the rules to make it resemble the correct shape, but the colors don't match. Exactly why it doesn't fit remains a matter for debate. But I am fundamentally sure of the *fact* that it doesn't. (Will be away from the screen now until about Tuesday.) -- 73 from Ian GM3SEK 'In Practice' columnist for RadCom (RSGB) http://www.ifwtech.co.uk/g3sek |
Current across the antenna loading coil - from scratch
K7ITM wrote:
Another 'speriment occured to me, for those who think the coil current MUST be different at the two ends by the amount corresponding to the antenna section it replaces: To the best of my knowledge, nobody believes that. The coil is much more efficient at the loading function than is the straight wire from which it is made. That's why inductive loading is more efficient than fractal antennas or other types of linear loading. -- 73, Cecil http://www.qsl.net/w5dxp |
Current across the antenna loading coil - from scratch
wrote in message
oups.com... Yuri Blanarovich wrote: W8JI and other unbelievers that antenna and loading coils can not be expressed in electrical degrees, can find another example in ON4UN's Low Band DXing book, 4th edition, page 9-47, Fig 9-58, showing loaded vertical with mast being 40 deg. 59.6 ft. long, loading coil of 144 uH taking (replacing radiator of) 40 deg and whip of 10 deg and 14.9 ft long, for overall 90 deg electrical and quarter wave resonant system. Soooo, to anyone outside of "equal current worshippers" it is obvious that coil is replacing 40 deg worth of radiator and it would drop equivalent amount of current across the coil that corresponds to the length of radiator that coil replaces, because rest of the "straight" radiator FORCES IT TO DO - because of standing wave and current. That is not correct Yuri. Anything from a pure inductance to a very poor distributed inductor (like a linear loading or stub) can be used and all would have different characteristics. "Pure inductance" - get me one, never subject of discussion here, about real antennas and real loading coils! A pure inductance would have no current difference at each end. A good compact inductor would have negligible current difference at each end, only a long straight wire would act like the "missing antenna". More BS, insisting on non-reality. One way to prove the coil does not replace missing length is to simply move the coil to a new location in a fixed height antenna. If the coil looked like 40 degrees, it would resonate the antenna no matter where it was installed. WRONG, read below, it's the required inductance/impedance and fixed "missing" degrees that need replacement. 73 Tom Another big WRONGO Tom! As we go deeper into the discussion and "arguments" from "unbelievers" and thanks to NM5K posting, about how fixed coil acts different, replaces different amount of degrees, it hit me that the reason is the impedance presented by the antenna (the straight part) radiator at the coil insertion point. Using just as example, radiator having 90 degrees at the resonance, with 50 degrees of whip and coil "replacing" 40 degrees in the said example from the book. You agree that impedance along the radiator changes, being low at the bottom, around tens of ohms, to being high at the top, around thousands of ohms. Now you place the loading coil along the radiator, one extreme being at the bottom, low impedance point - we know in order to maintain the resonance of say 13 ft high (long) radiator (90 electrical degrees at RESONANCE) the coil has a fewer turns, it's impedance is lower (as required by the lower impedance at the bottom end of the antenna), and current drop would relatively be small as W7EL proved and everybody knows. Now you move that coil say half way up the must, to higher impedance point at the antenna, and that coil now, in order to maintain the "match" has to have higher impedance, more turns and will exhibit MORE current drop across it, while replacing THE SAME NUMBER OF "missing" DEGREES AT THE RADIATOR. Assuming that our goal is to stay with the same physical length of the whip (which we do) and maintaining 90 degrees of resonant radiator. So the radiator stays 50 degrees ()+50, 10+40, 20+30, 30+20, 40 + 10) long and coil replaces the same "missing" 40 degrees. Same if you move the coil higher, higher antenna impedance point, more turns (inductance) required, more current drop exhibited, coil "replacing" THE SAME NUMBER OF 40 DEGREES. It needs more turns, but again, the coil's behavior is dictated by the impedance of the RADIATOR (standing waves) at the insertion point, dictating the inductance, number of turns of the coil in order to maintain the number of degrees, in order to maintain the resonance (90 degrees) of the radiator. In order to "overturn" this "Yuri's Theory" you would have to deny that resonant antenna has varying current across its radiator (wire) - to deny that current drops from the base to the tip. You would have to deny that coil in the RF circuit has varying impedance dependant on the number of turns and inductance and frequency. Deny that in order to maintain the resonant frequency of shortened radiator of the same physical length, you need to use coils of varying amount of turns depending on its insertion point along the radiator (less on the bottom, more closer to the top). That behavior of the coil is "FORCED" by the remaining "wires" in the radiator, in standing wave environment as Cecil is trying to get through with help of Kraus and others. So if the antenna is 50 degrees long and we want to maintain the resonance, the coil will replace (has to) the same 40 degrees regardless where it is placed, but its inductance and impedance will vary, depending on the impedance of the insertion point at the radiator. (Makes also sense - more turns - more current drop, RF choke effect. We are still talking RF current in standing wave antenna, not DC.) So the drop of RF current across the coil, depending on its position in the resonant quarter wave radiator can be from little at the base, to significant closer to the top, dependent on the position, insertion point, impedance of the radiator. This is much more significant cause of current drop across the coil that any "radiation or capacitance to the environment" (Tom's trying to "twist out of it") as is demonstrated by our arguments. So if we look at the fixed length of radiator and try to bring it to resonance with coils, placed at different locations along the radiator, we are replacing the SAME amount of electrical degrees, but depending on the required impedance, then the number of turns, or inductance has to be adjusted to conform. That jives what you and everybody knows and keep saying. So it is not the fixed inductance, (missing) length of wire in the coil, or same number of turns that replaces degrees of "missing" radiator, but the REQUIRED INDUCTANCE/IMPEDANCE and corresponding number of turns. I hope this makes it little bit more clear and shuts down another WRONGOOO that keeps popping up. Just measure it, stick it (properly defined) in EZNEC - IT IS ALL THERE, for everyone to see. So then if the standing wave causes drop of the RF current across the solid wire of the antenna, it also causes the drop of current across the loading coil, proportional to the amount of electrical degrees of radiator that coil "replaces", magnitude being dependent on the impedance and inductance required by the insertion point impedance along the radiator. (Almost sounds like "Yuri's Law" :-) I would like to thank NM5K for bringing it up and making me to understand what the "problem" and proof is. It made me realize what role impedance of the inductor plays in the STANDING WAVE antenna/circuit. Sooo! The coil can and have RF current variation, drop across it, just like piece of wire can, when in standing wave (antenna) environment. It is the major cause and not the whatever capacitance etc. You wanna call it K3BU's theory, I would be honored, but I do not claim any "ownership", many others before me showed that, directly or indirectly, including John Kraus, W8JK. I promise to do that article and series of experiments showing close correlation between measurements and proper modeling in EZNEC, just give me couple of weeks. I hope it will show and educate those willing to open their minds, and those "flat Earthers" can do what they choose to (look silly). I hope I made it more clear. I don't know how else I (we) can get it through! Soooo, but, but, but.... what? Yuri Blanarovich, K3BU.us I apologize to technical language purists for any clumsy wordiness' I may be guilty of. |
Current across the antenna loading coil - from scratch
Roy,
please see my other posting, otherwise, I really promise to do the step by step article, which will try to explain, correlate real life measurements and modeling and present the comprehensive case of current being different across antenna loading coils. Will do that with cooperation of other "defenders" that contributed to "our" cause. There is no point of going back and forth on tangents. We will measure, show the reality and then apply some theory, explanation and summary of what is going on. I hope it will correct misconceptions, provide better understanding and benefit in proper modeling and design of loaded antenna elements and systems. Otherwise, I think we have reached point, when it is pointless to go around in circles and argue that what IS, CAN'T BE, because..... Yuri, K3BU "Roy Lewallen" wrote in message ... Of course loading coils can be expressed in electrical degrees. But extrapolating this to mean that a loading coil has the same properties as an antenna with the same number of "degrees" has no justification. Yuri's theory was shown to be false not only by many of the good technical arguments given here in this thread, but also by a careful measurement I made over a year ago. I built a 33 foot high vertical and loaded it at the bottom with a toroidal inductor to resonate it at 3.8 MHz. The coil "replaced" 33.4 electrical degrees of antenna. Yuri's theory predicts that the current at the top of the inductor should be 16.5% less than that at the bottom, with a phase shift of 33.4 degrees. What I measured was a current drop of 5.4% and no measurable phase shift across the inductor. Both the description of the setup and the detailed results were posted on this newsgroup on Nov. 11, 2003, with the subject title " Current in antenna loading coils controversy - new measurement". Anyone can find those postings with groups.google.com. Yuri's response, also on Nov. 11, 2003 was to complain about my methodology, declare that he was still right, and state "I will measure things myself, try to verify previous measurements and then come up with conclusions and 'theory'." On Nov. 12, 2003, he posted: "I will be making snap-on current probe, which will make it easier to slide along the element and observe the current without the disturbance to the antenna and will be a bit different over the thermocouple meters. Just need a bit more time." Well, it's been over a year now, and all I've seen is the same unsupported theory with no evidence to contradict the contrary evidence which has been presented. When a belief stays fixed in spite of both contradictory solid theory and measurements, it fits into the category of religion, not science. So it's appropriate that Yuri speaks in terms of an explanation being a "heresy". What's next, "good" and "evil" theories? Roy Lewallen, W7EL Yuri Blanarovich wrote: W8JI and other unbelievers that antenna and loading coils can not be expressed in electrical degrees, can find another example in ON4UN's Low Band DXing book, 4th edition, page 9-47, Fig 9-58, showing loaded vertical with mast being 40 deg. 59.6 ft. long, loading coil of 144 uH taking (replacing radiator of) 40 deg and whip of 10 deg and 14.9 ft long, for overall 90 deg electrical and quarter wave resonant system. Soooo, to anyone outside of "equal current worshippers" it is obvious that coil is replacing 40 deg worth of radiator and it would drop equivalent amount of current across the coil that corresponds to the length of radiator that coil replaces, because rest of the "straight" radiator FORCES IT TO DO - because of standing wave and current. Such a heresy! Theeere is your sign! Yuri, K3BU/m |
Current across the antenna loading coil - from scratch
I fail to see what you are all arguing about.
A length of transmission line, or a coil insofar as it behaves as a length of transmission line, has a fixed number of degrees of phase shift which depends only on frequency. You can shift it about, put it in a different antenna, do what you like with it, but, at the same frequency, it will always have the same number of degrees. Now stop this childish argument before I bang your heads together. ---- Referee Reg. |
Current across the antenna loading coil - from scratch
"Roy Lewallen" wrote:
Of course loading coils can be expressed in electrical degrees. But extrapolating this to mean that a loading coil has the same properties as an antenna with the same number of "degrees" has no justification. I haven't heard anybody make that assertion in years. Coils occupy whatever number of degrees that they occupy. The technical fact is that standing wave current phase cannot be used as the method of measuring the number of degrees. The graphic at http://www.travstnd.GIF shows why. The standing wave current phase is unchanging unless the monopole length goes over 1/4WL. Here's what you said earlier: I said that Cecil's phase measurements agree with EZNEC (and generally accepted theory) -- there should be almost no phase shift in the current along the wire. If there's no phase shift along the wire, why would you expect to measure phase shift through a coil. After you made the above posting, I thought you understood that - but apparently not. I told you that your phase shift measurement was invalid a year ago and it is just as invalid now as it was then. There is no phase information contained in standing wave current phase. This is the basic misconception that has resulted in invalid data reported by you. What I measured was a current drop of 5.4% and no measurable phase shift across the inductor. But Roy, you used standing wave current phase to try to measure the phase shift across the inductor. The standing wave current phase is known to be unchanging in a wire. Why would you expect it to change through a coil? As Gene Fuller says, the only phase information in the standing wave current is in the magnitude measurement. If the magnitude changed by 5.4%, the phase shift was roughly arc-cos(1 - 0.054) = arc-cos(0.946) = ~19 degrees. Please take a look at what EZNEC says about the standing wave phase shift in 1/4WL of wire at: http://www.qsl.net/w5dxp/travstnd.GIF and please tell us again how you used a current with an unchanging flat phase to try to measure the phase shift through a coil. Well, it's been over a year now, and all I've seen is the same unsupported theory with no evidence to contradict the contrary evidence which has been presented. No evidence? Even EZNEC says one cannot use standing wave current phase to measure phase shift. I told you that fact over a year ago. Your phase measurement methods are just as invalid today as they were a year ago. When a belief stays fixed in spite of both contradictory solid theory and measurements, it fits into the category of religion, not science. You are talking about your religious method of using the unchanging standing wave current phase to try to measure a phase shift. EZNEC says that is not a valid approach. Even Gene Fuller says there is zero phase information in standing wave current wave and he generally agrees with you. Regarding the cos(kz)*cos(wt) term in a standing wave: Gene Fuller, W4SZ wrote: In a standing wave antenna problem, such as the one you describe, there is no remaining phase information. Any specific phase characteristics of the traveling waves died out when the startup transients died out. Phase is gone. Kaput. Vanished. Cannot be recovered. Never to be seen again. The only "phase" remaining is the cos (kz) term, which is really an amplitude description, not a phase. -- 73, Cecil http://www.qsl.net/w5dxp |
Current across the antenna loading coil - from scratch
"Roy Lewallen" wrote: I'm afraid that the proponents of the alternative theories aren't subject to either modeling or measurement results. There's already ample theoretical, modeling, and measurement evidence to show that the theory is faulty; further efforts would be a waste of time. Roy, it is you who are ignoring the results of EZNEC. EZNEC proves that one cannot use standing wave current phase to measure the phase shift through a wire, much less through a coil. To see why, take a look at: http://www.qsl.net/w5dxp/travstnd.GIF The standing wave current is absolutely FLAT. It cannot be used for any valid measurement. -- 73, Cecil, W5DXP |
Current across the antenna loading coil - from scratch
"Yuri Blanarovich" wrote:
Otherwise, I think we have reached point, when it is pointless to go around in circles and argue that what IS, CAN'T BE, because..... Yuri, I think it is obvious that some people are suffering from misconceptions. The misconception that the "experts" are suffering from has *nothing* to do with coils. That's the reason the coil discussion has gone in circles. There may not be anything wrong with the coil concepts. The misconception is about standing wave current VS traveling wave current. The "experts" have asserted that "current is current" and that standing wave current is the same as traveling wave current even though they have different equations. Even EZNEC recognizes the difference between standing wave current and traveling wave current. I took a quarter wavelength of wire and drove it as a standing wave wire and as a traveling wave wire. The piece of wire was identical in both cases. I've posted the EZNEC results a number of times and none of the "experts" have responded. Here they are again: The corresponding EZNEC files are available at: http://www.qsl.net/w5dxp/TravWave.EZ I(x,t)=Io*cos(kx+wt) http://www.qsl.net/w5dxp/StndWave.EZ I(x,t)==Io*cos(kx)*cos(wt) % along current in current in wire #2 TravWave.EZ StndWave.EZ 0.28% 0.9998 at -0.99 deg 0.9996 at 0 deg 9.72% 0.9983 at -9.39 deg 0.9843 at -0.03 deg 19.7% 0.9969 at -18.23 deg 0.9454 at -0.05 deg 30.3% 0.9957 at -27.59 deg 0.8843 at -0.06 deg 39.7% 0.9949 at -35.96 deg 0.8023 at -0.08 deg 49.7% 0.9945 at -44.84 deg 0.7014 at -0.09 deg 60.3% 0.9945 at -54.20 deg 0.5840 at -0.09 deg 69.7% 0.9949 at -62.58 deg 0.4528 at -0.10 deg 79.7% 0.9956 at -71.43 deg 0.3110 at -0.11 deg 89.7% 0.9965 at -80.27 deg 0.1616 at -0.11 deg 99.7% 0.9976 at -89.14 deg 0.0061 at -0.11 deg These values reported by EZNEC are graphed at: http://www.qsl.net/w5dxp/travstnd.GIF Their differences are obvious. One might even argue that they are opposites. The traveling wave magnitude looks like the standing wave phase. The traveling wave phase looks like the standing wave magnitude. That fits perfectly with Gene Fuller's assertion that there is no phase information in standing wave current phase. The only phase information in the standing wave current is in the magnitude. Once the "experts" realize that is the source of their misconception, everything will fall into place. Again, it is NOT about coils. It is all about misconceptions involving standing wave current. -- 73, Cecil, W5DXP |
Current across the antenna loading coil - from scratch
"Reg Edwards" wrote: I fail to see what you are all arguing about. Here's the argument in a nutshell, Reg. Can standing wave current phase be used to determine the phase shift through a coil (or through a wire)? Some of us say, No. Some of the "experts" say, Yes, but so far have failed to explain how or why that is a valid measurement technique. -- 73, Cecil, W5DXP |
Current across the antenna loading coil - from scratch
Yuri Blanarovich wrote: A pure inductance would have no current difference at each end. A good compact inductor would have negligible current difference at each end, only a long straight wire would act like the "missing antenna". More BS, insisting on non-reality. No, it is factual. No need to call names or get angry. It is the stray capacitance from the inductor to the outside world that allows any difference in current. Not the standing waves, not the missing area of antenna. I can have a fixed antenna and with no change other than the style of coil have anything from nearly immeasurable differences to large differences. For example if the coil is a very large area single turn, it will behave almost like the "missing degrees" you talk about. If it is a compact inductor and has low capacitance to the outside world compared to the antenna above the coil, it will have very little current difference. One way to prove the coil does not replace missing length is to simply move the coil to a new location in a fixed height antenna. If the coil looked like 40 degrees, it would resonate the antenna no matter where it was installed. WRONG, read below, it's the required inductance/impedance and fixed "missing" degrees that need replacement. As we go deeper into the discussion and "arguments" from "unbelievers" and thanks to NM5K posting, about how fixed coil acts different, replaces different amount of degrees, it hit me that the reason is the impedance presented by the antenna (the straight part) radiator at the coil insertion point. Using just as example, radiator having 90 degrees at the resonance, with 50 degrees of whip and coil "replacing" 40 degrees in the said example from the book. What NM5K posting is that? A coil is a coil. It doesn't know where you are using it. You teminate it with a certain impedance, it operates the same way. You can call it "40 degrees" or anything you like, but you better not think it acts like that missing antenna area so far as phase shift or current difference between ends. It doesn't act that way. If it DID act the way you seem to be saying, a base loaded antenna would be a terrible antenna. Yet over a good groundplane with a reasonable inductor design, they can be very good. You agree that impedance along the radiator changes, being low at the bottom, around tens of ohms, to being high at the top, around thousands of ohms. I never said that. What do you mean by reactance? The X can be very high but radiation resistance very low even near the open end. Now you place the loading coil along the radiator, one extreme being at the bottom, low impedance point - we know in order to maintain the resonance of say 13 ft high (long) radiator (90 electrical degrees at RESONANCE) the coil has a fewer turns, it's impedance is lower (as required by the lower impedance at the bottom end of the antenna), and current drop would relatively be small as W7EL proved and everybody knows. So you admit your "my coil replaces 40 degrees" doesn't work? Or what are you saying? Now you move that coil say half way up the must, to higher impedance point at the antenna, and that coil now, in order to maintain the "match" has to have higher impedance, more turns and will exhibit MORE current drop across it, while replacing THE SAME NUMBER OF "missing" DEGREES AT THE RADIATOR. So the " 40 degrees" is just a meaningless number. It doesn't mean anything so far as the coil goes. I'll go along with that. Assuming that our goal is to stay with the same physical length of the whip (which we do) and maintaining 90 degrees of resonant radiator. So the radiator stays 50 degrees ()+50, 10+40, 20+30, 30+20, 40 + 10) long and coil replaces the same "missing" 40 degrees. As long as we both agree it does not have anywhere near the same amount of current difference from start to finish the same length of antenna would have, I agree. If you are claiming the current difference at each end of the coil relates to electrical degrees it "replaces" and not capacitance from the coil to the outside world, I disagree. Same if you move the coil higher, higher antenna impedance point, more turns (inductance) required, more current drop exhibited, coil "replacing" THE SAME NUMBER OF 40 DEGREES. It needs more turns, but again, the coil's behavior is dictated by the impedance of the RADIATOR (standing waves) at the insertion point, dictating the inductance, number of turns of the coil in order to maintain the number of degrees, in order to maintain the resonance (90 degrees) of the radiator. The only reason why the inductor could have more "current drop" (what a concept! current doesn't drop.) is because displacement current from capacitance can be a larger portion of load impedance. The coil, in effect, it acting a bit like a tiny "hat" and robbingh the whip above the coil of current. Some displacement current branches off to the world around the coil, leaving less to travel upwards. In order to "overturn" this "Yuri's Theory" you would have to deny that resonant antenna has varying current across its radiator (wire) - to deny that current drops from the base to the tip. I'm not sure what you are saying there. You would have to deny that coil in the RF circuit has varying impedance dependant on the number of turns and inductance and frequency. Deny that in order to maintain the resonant frequency of shortened radiator of the same physical length, you need to use coils of varying amount of turns depending on its insertion point along the radiator (less on the bottom, more closer to the top). That behavior of the coil is "FORCED" by the remaining "wires" in the radiator, in standing wave environment as Cecil is trying to get through with help of Kraus and others. You are free to think what you like, but I don't think Kraus is helping Cecil. While a properly done use of standing waves would work, my opinion is Cecil just has a fixation on it and is trying to change the behavior of the system to match his misapplication of standing waves to the coil. I can take the VERY SAME radiator, make no change in coil location at all, and change the current ratio at the start of the inductor and end of the inductor ONLY by changing inductor design. This is with the antenna operated on one frequency, with one coil location, and with the feedpoint at X=0 (resonance). If your theory about standing waves or the "40 degree replacement" theory is correct, I sould not be able to do that. Yet I can. I can build a loading coil that has almost no current difference across the length, change nothing else but the coil, and wind up with almost anything I like for current difference. The reason that happens is displacement current and the fields around the coil. It is not a function of standing waves or the "missing area" the coil replaces. It takes a lot less than three years of name calling and arguing to measure it, assuming people can channel their energy into doing something besides running around talking about people or arguing. 73 Tom |
Current across the antenna loading coil - from scratch
Yuri Blanarovich wrote: A pure inductance would have no current difference at each end. A good compact inductor would have negligible current difference at each end, only a long straight wire would act like the "missing antenna". More BS, insisting on non-reality. No, it is factual. No need to call names or get angry. It is the stray capacitance from the inductor to the outside world that allows any difference in current. Not the standing waves, not the missing area of antenna. I can have a fixed antenna and with no change other than the style of coil have anything from nearly immeasurable differences to large differences. For example if the coil is a very large area single turn, it will behave almost like the "missing degrees" you talk about. If it is a compact inductor and has low capacitance to the outside world compared to the antenna above the coil, it will have very little current difference. One way to prove the coil does not replace missing length is to simply move the coil to a new location in a fixed height antenna. If the coil looked like 40 degrees, it would resonate the antenna no matter where it was installed. WRONG, read below, it's the required inductance/impedance and fixed "missing" degrees that need replacement. As we go deeper into the discussion and "arguments" from "unbelievers" and thanks to NM5K posting, about how fixed coil acts different, replaces different amount of degrees, it hit me that the reason is the impedance presented by the antenna (the straight part) radiator at the coil insertion point. Using just as example, radiator having 90 degrees at the resonance, with 50 degrees of whip and coil "replacing" 40 degrees in the said example from the book. What NM5K posting is that? A coil is a coil. It doesn't know where you are using it. You teminate it with a certain impedance, it operates the same way. You can call it "40 degrees" or anything you like, but you better not think it acts like that missing antenna area so far as phase shift or current difference between ends. It doesn't act that way. If it DID act the way you seem to be saying, a base loaded antenna would be a terrible antenna. Yet over a good groundplane with a reasonable inductor design, they can be very good. You agree that impedance along the radiator changes, being low at the bottom, around tens of ohms, to being high at the top, around thousands of ohms. I never said that. What do you mean by reactance? The X can be very high but radiation resistance very low even near the open end. Now you place the loading coil along the radiator, one extreme being at the bottom, low impedance point - we know in order to maintain the resonance of say 13 ft high (long) radiator (90 electrical degrees at RESONANCE) the coil has a fewer turns, it's impedance is lower (as required by the lower impedance at the bottom end of the antenna), and current drop would relatively be small as W7EL proved and everybody knows. So you admit your "my coil replaces 40 degrees" doesn't work? Or what are you saying? Now you move that coil say half way up the must, to higher impedance point at the antenna, and that coil now, in order to maintain the "match" has to have higher impedance, more turns and will exhibit MORE current drop across it, while replacing THE SAME NUMBER OF "missing" DEGREES AT THE RADIATOR. So the " 40 degrees" is just a meaningless number. It doesn't mean anything so far as the coil goes. I'll go along with that. Assuming that our goal is to stay with the same physical length of the whip (which we do) and maintaining 90 degrees of resonant radiator. So the radiator stays 50 degrees ()+50, 10+40, 20+30, 30+20, 40 + 10) long and coil replaces the same "missing" 40 degrees. As long as we both agree it does not have anywhere near the same amount of current difference from start to finish the same length of antenna would have, I agree. If you are claiming the current difference at each end of the coil relates to electrical degrees it "replaces" and not capacitance from the coil to the outside world, I disagree. Same if you move the coil higher, higher antenna impedance point, more turns (inductance) required, more current drop exhibited, coil "replacing" THE SAME NUMBER OF 40 DEGREES. It needs more turns, but again, the coil's behavior is dictated by the impedance of the RADIATOR (standing waves) at the insertion point, dictating the inductance, number of turns of the coil in order to maintain the number of degrees, in order to maintain the resonance (90 degrees) of the radiator. The only reason why the inductor could have more "current drop" (what a concept! current doesn't drop.) is because displacement current from capacitance can be a larger portion of load impedance. The coil, in effect, it acting a bit like a tiny "hat" and robbingh the whip above the coil of current. Some displacement current branches off to the world around the coil, leaving less to travel upwards. In order to "overturn" this "Yuri's Theory" you would have to deny that resonant antenna has varying current across its radiator (wire) - to deny that current drops from the base to the tip. I'm not sure what you are saying there. You would have to deny that coil in the RF circuit has varying impedance dependant on the number of turns and inductance and frequency. Deny that in order to maintain the resonant frequency of shortened radiator of the same physical length, you need to use coils of varying amount of turns depending on its insertion point along the radiator (less on the bottom, more closer to the top). That behavior of the coil is "FORCED" by the remaining "wires" in the radiator, in standing wave environment as Cecil is trying to get through with help of Kraus and others. You are free to think what you like, but I don't think Kraus is helping Cecil. While a properly done use of standing waves would work, my opinion is Cecil just has a fixation on it and is trying to change the behavior of the system to match his misapplication of standing waves to the coil. I can take the VERY SAME radiator, make no change in coil location at all, and change the current ratio at the start of the inductor and end of the inductor ONLY by changing inductor design. This is with the antenna operated on one frequency, with one coil location, and with the feedpoint at X=0 (resonance). If your theory about standing waves or the "40 degree replacement" theory is correct, I sould not be able to do that. Yet I can. I can build a loading coil that has almost no current difference across the length, change nothing else but the coil, and wind up with almost anything I like for current difference. The reason that happens is displacement current and the fields around the coil. It is not a function of standing waves or the "missing area" the coil replaces. It takes a lot less than three years of name calling and arguing to measure it, assuming people can channel their energy into doing something besides running around talking about people or arguing. 73 Tom |
Current across the antenna loading coil - from scratch
"Cecil Moore" wrote Can standing wave current phase be used to determine the phase shift through a coil (or through a wire)? ======================================= Cec and Co. I couldn't care two hoots about standing waves, whatever they are. As described in this newsgroup it's all just just a load of nonsense. KISS. And forget all about SWR. ---- Reg. |
Current across the antenna loading coil - from scratch
"Reg Edwards" wrote: I couldn't care two hoots about standing waves, whatever they are. The "experts" have that same problem, Reg, yet they are using standing wave current phase to try to measure phase shift through a coil, a known invalid approach since standing wave current phase doesn't contain any phase information. -- 73, Cecil, W5DXP |
Current across the antenna loading coil - from scratch
wrote: It is the stray capacitance from the inductor to the outside world that allows any difference in current. Not the standing waves, not the missing area of antenna. You are using standing wave current to try to prove your concepts are valid. If you don't take time to understand standing wave current, you will never correct those misconceptions. Standing wave current phase contains no phase information. Therefore, standing wave current phase cannot be used to measure the phase shift through a wire or a coil. The only phase information in a standing wave current is in the magnitude which roughly follows a cosine function distorted by the fields in the loading coil. If the current at the bottom of the coil is 1.0 amps and the current at the top of the coil is 0.7 amps, the phase shift through the coil is *roughly* arc-cos(0.7) = ~45 degrees. As Gene Fuller says, there's no phase information in standing wave current phase. All the phase information is embedded in the magnitude. That's easy to see from the I(x,t) = Io*cos(kx)*cos(wt) equation for standing wave current. It's also easy to see from: http://www.qsl.net/w5dxp/travstnd.GIF plotted from EZNEC data. -- 73, Cecil, W5DXP |
Current across the antenna loading coil - from scratch
Cecil Moore wrote:
I've posted the EZNEC results a number of times and none of the "experts" have responded. Cecil, I wonder why? Fool me once, shame on you. Fool me twice, shame on me. Fool me thrice, what an idiot I must be. 73, Gene W4SZ |
Current across the antenna loading coil - from scratch
Cecil Moore wrote:
The misconception is about standing wave current VS traveling wave current. The "experts" have asserted that "current is current" and that standing wave current is the same as traveling wave current even though they have different equations. Cecil, So how is your study of the NEC documents going? I learn something new every time I plow through the mathematical discussion. I find current discussed on almost every page, but I am still searching for the part that discusses standing waves and traveling waves. If you could help me find that section it would be appreciated. 73, Gene W4SZ |
Current across the antenna loading coil - from scratch
Gene Fuller wrote: Cecil Moore wrote: The misconception is about standing wave current VS traveling wave current. The "experts" have asserted that "current is current" and that standing wave current is the same as traveling wave current even though they have different equations. Cecil, So how is your study of the NEC documents going? I learn something new every time I plow through the mathematical discussion. I find current discussed on almost every page, but I am still searching for the part that discusses standing waves and traveling waves. If you could help me find that section it would be appreciated. 73, Gene W4SZ Gene, Don't hold your breath while waiting for Cecil to agree the NEC engine he uses to prove you can only calculate current by using reflected waves does not use reflected waves! I'm still trying to find out why my meter measures standing wave current and not "real current", or whatever the heck he is saying. I just made a QSO with Australia and got a 599 and I only used standing wave current! Imagine how loud I would have been if I used real current. 73 Tom |
Current across the antenna loading coil - from scratch
Gene Fuller wrote:
Cecil Moore wrote: I've posted the EZNEC results a number of times and none of the "experts" have responded. Cecil, I wonder why? Fool me once, shame on you. Fool me twice, shame on me. Fool me thrice, what an idiot I must be. Gene, I don't make fools of the "experts". They do that to themselves through such statements as "current is current", implying that standing wave current is identical to traveling wave current which you know is NOT the case (thanks for your earlier posting). Wouldn't it be better to explain standing wave current to the "experts" in a private email than attacking me here for "fooling the experts"? You and I are in essential agreement. It's the "experts" who use standing wave current phase to measure phase who are, in your words above, the "idiots". Considering a technical discussion to be fooling the "experts" speaks volumes, doesn't it? And indeed, Ian said it best. He said something to the effect that I try to sucker the experts into an argument when I am right. That says it all and shows why the "experts" won't engage me when they know that they are wrong. -- 73, Cecil http://www.qsl.net/w5dxp |
Current across the antenna loading coil - from scratch
Reg Edwards wrote:
SNIPPED ======================================= Cec and Co. I couldn't care two hoots about standing waves, whatever they are. As described in this newsgroup it's all just just a load of nonsense. KISS. And forget all about SWR. ---- Reg. Reminds me of an engineer who used to work for me: "The H-LL with VSWR! I can make anything radiate." He was close to right!! |
Current across the antenna loading coil - from scratch
Gene Fuller wrote:
So how is your study of the NEC documents going? I don't understand it yet. But EZNEC does understand it since EZNEC reports the correct results for both traveling wave current and standing wave current. I just downloaded an updated graphic to http://www.qsl.net/w5dxp/travstnd.GIF but qsl.net is so unreliable I haven't been able to view it yet. I learn something new every time I plow through the mathematical discussion. I find current discussed on almost every page, but I am still searching for the part that discusses standing waves and traveling waves. Glad you asked, Gene, regarding the cos(kz)*cos(wt) term in a standing wave: Gene Fuller, W4SZ wrote: In a standing wave antenna problem, such as the one you describe, there is no remaining phase information. Any specific phase characteristics of the traveling waves died out when the startup transients died out. Phase is gone. Kaput. Vanished. Cannot be recovered. Never to be seen again. The only "phase" remaining is the cos (kz) term, which is really an amplitude description, not a phase. One can see from my above graphic that EZNEC indeed does differentiate between traveling waves and standing waves. So how does EZNEC do that? EZNEC agrees with your above posting but I don't yet know how it knows. -- 73, Cecil http://www.qsl.net/w5dxp |
Current across the antenna loading coil - from scratch
wrote:
I'm still trying to find out why my meter measures standing wave current and not "real current", or whatever the heck he is saying. It's all explained by the EZNEC data that I have posted half a dozen times before to which you haveyet to responded. In case you could possibly have missed it, here it is again: % along current in current in wire #2 TravWave.EZ StndWave.EZ 0.28% 0.9998 at -0.99 deg 0.9996 at 0 deg 9.72% 0.9983 at -9.39 deg 0.9843 at -0.03 deg 19.7% 0.9969 at -18.23 deg 0.9454 at -0.05 deg 30.3% 0.9957 at -27.59 deg 0.8843 at -0.06 deg 39.7% 0.9949 at -35.96 deg 0.8023 at -0.08 deg 49.7% 0.9945 at -44.84 deg 0.7014 at -0.09 deg 60.3% 0.9945 at -54.20 deg 0.5840 at -0.09 deg 69.7% 0.9949 at -62.58 deg 0.4528 at -0.10 deg 79.7% 0.9956 at -71.43 deg 0.3110 at -0.11 deg 89.7% 0.9965 at -80.27 deg 0.1616 at -0.11 deg 99.7% 0.9976 at -89.14 deg 0.0061 at -0.11 deg I have graphed these EZNEC results and they are available at: http://www.qsl.net/w5dxp/travstnd.GIF The corresponding EZNEC files are available at: http://www.qsl.net/w5dxp/TravWave.EZ http://www.qsl.net/w5dxp/StndWave.EZ Would you please explain why you are avoiding these results which expose your misconceptions about standing wave current unless exposing your misconceptions is what you are avoiding? -- 73, Cecil http://www.qsl.net/w5dxp |
Current across the antenna loading coil - from scratch
wrote:
You can weave a little tidbit of fact into a big misconception or diversion if you like, but don't expect others to buy into the misconception. When are you going to discuss the technical difference between I(x,t)=Io*cos(kx+wt) and I(x,t)=Io*cos(kx)*cos(wt)? The only place those two currents are equal is when x=0. At any other point, they are virtually opposites of each other. The differences in those two equations is what led you to believe the currents at each end of a coil are identical based on measurements. You guys used a signal, the standing wave current signal, that is incapable of distinguishing a phase shift even in a wire, much less in a coil. The current you measure with a clamp on meter or any other reliable current meter that does not greatly perturb the circuit is the current that causes radiation, it is the current that causes heating, and it is the current we would use to calculate power. There's absolutely no argument about that. Both forward waves and reflected waves radiate so standing waves obviously radiate. Both forward waves and reflected waves cause I^2*R losses. Stating such obvious technical facts is a diversion and a waste of words. The phase of that current is the phase of the current that causes radiation, heating, and that we would use to calculate patterns. The phase of standing wave current is unchanging. That's why we get broadside radiation from a 1/2WL standing wave dipole and end fire radiation from a traveling wave antenna. But again, stating such obvious technical facts is a diversion and a waste of words. When are you going to discuss the actual technical issues? -- 73, Cecil http://www.qsl.net/w5dxp |
Current across the antenna loading coil - from scratch
Cecil Moore wrote:
These values reported by EZNEC are graphed at: http://www.qsl.net/w5dxp/travstnd.GIF Clicking that URL causes Firefox to report: "The operation timed out when attempting to contact proxy.qsl.net." Pasting that URL into Opera causes it to just sit there and do nothing. I just thought you'd like to know. Cheers, John |
Current across the antenna loading coil - from scratch
John - KD5YI wrote:
Cecil Moore wrote: These values reported by EZNEC are graphed at: http://www.qsl.net/w5dxp/travstnd.GIF Clicking that URL causes Firefox to report: "The operation timed out when attempting to contact proxy.qsl.net." Pasting that URL into Opera causes it to just sit there and do nothing. I just thought you'd like to know. I apologize for qsl.net being so unreliable. Please try again later. I'm going to get a more reliable web server just as soon as I get a round tuit. -- 73, Cecil http://www.qsl.net/w5dxp |
Current across the antenna loading coil - from scratch
Yuri Blanarovich wrote:
Roy, please see my other posting, otherwise, I really promise to do the step by step article, which will try to explain, correlate real life measurements and modeling and present the comprehensive case of current being different across antenna loading coils. Will do that with cooperation of other "defenders" that contributed to "our" cause. There is no point of going back and forth on tangents. We will measure, show the reality and then apply some theory, explanation and summary of what is going on. I hope it will correct misconceptions, provide better understanding and benefit in proper modeling and design of loaded antenna elements and systems. Otherwise, I think we have reached point, when it is pointless to go around in circles and argue that what IS, CAN'T BE, because..... Before you get too carried away, look back in this thread where Cecil posted a URL to his web site where he had an EZNEC (helical wire) model of a coil at the base of a short whip. It showed significant current drop from the bottom to the top, although no significant phase shift. I replaced the whip part of the antenna with a wire directly to ground from the top of the coil which contained a lumped RC to substitute for the whip's impedance. The drop across the coil remained the same. So in the course of developing your theory, you should explain why this happens, since there are no longer the traveling and standing waves which were on the whip. This model was, and still is, posted on my web site. Then, to illustrate that the current drop from bottom to top is due to shunt C, I removed the ground in the model, converting the model to free space. I connected the bottom of the coil to the bottom of the new wire with a wire instead of via the ground connection. The current drop from bottom to top of the coil disappeared. (There's still a minor difference due to several factors I mentioned in my posting.) The fact that the current drop is the same for an antenna and for a lumped circuit with the same impedance was also verified by measurements I made and posted over a year ago. Those model results are consistent with what I, Tom, and others have been saying, and consistent with classical, known, circuit theory. They aren't consistent at all with all this standing wave - traveling wave - antenna replacement business. I've looked very carefully at the models and concluded that EZNEC is operating well within its capabilities, so the results are valid. So for starters, why don't you explain how your theory fits with the existing model results? Why is the current drop the same with an antenna and for a lumped circuit? Why does removing ground make the current drop go away? Why is there no significant phase shift in current from bottom to top? Conventional theory can explain this. Can yours? As for your promise to write the article, I have to point out that you've made this promise before without delivering. So I'm not exactly holding my breath waiting for it. I'm sure it'll make interesting reading, though, and it's a revolutionary enough theory that the IEEE, or at the very least QEX, should be happy to publish it when it's finally complete. Roy Lewallen, W7EL |
Current across the antenna loading coil - from scratch
Roy Lewallen wrote:
Before you get too carried away, look back in this thread where Cecil posted a URL to his web site where he had an EZNEC (helical wire) model of a coil at the base of a short whip. It showed significant current drop from the bottom to the top, although no significant phase shift. It showed a 10 degree phase shift. I've always said the phase shift is what it is but it is NOT zero. 10 degrees is definitely NOT zero even though you measured zero degrees shift. Wonder what was wrong with your measurements? So in the course of developing your theory, you should explain why this happens, since there are no longer the traveling and standing waves which were on the whip. Oh my, Roy, are you saying that zero ohms doesn't cause a reflection? If so, your misconceptions are worse than I thought. A short to ground causes exactly the same total reflection as an open-circuit, just with different phases. I would have expected you to realize that. I've looked very carefully at the models and concluded that EZNEC is operating well within its capabilities, so the results are valid. Yes, they are and they shoot down your argument. Please explain the results posted at: http://www.qsl.net/w5dxp/travstnd.GIF So for starters, why don't you explain how your theory fits with the existing model results? You first, Roy, since you disagree with EZNEC. -- 73, Cecil http://www.qsl.net/w5dxp |
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