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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 |
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