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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:
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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