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Cecil Moore wrote:
Gene Fuller wrote: Second, your analysis is utter rot! Are you suggesting that if the coil can be made resonant at some frequency, and then you cut it in half, that it still behaves the same? No, it behaves approximately like half of the original coil tending to have approximately the same Z0 and VF as the original coil. The phase shift through the coil will tend to be approximately 1/2 of the original phase shift - not exact because of end effects. Let's say we have a 1/4WL helical antenna with an obvious phase shift of 90 degrees. If we cut that helical in half, it is likely to have a phase shift of approximately 45 degrees, nowhere near the 4.5 degrees that W8JI has "measured". If we add a stinger to the above half-coil, we will have a base-loaded antenna. The phase shift will be relatively close to 45 degrees at the same frequency. The stinger contributes another few degrees. The impedance discontinuity between the coil and stinger contributes the rest of the 90 degrees of electrical length. "Utter rot" is a pretty good description of this. Your problem is that you've become so enamored of your little reflection theory that you insist that only a set of transmission lines 90 degrees in total length can resonate. Too bad your education isn't complete or you'd know this isn't so. 73, Tom Donaly, KA6RUH |
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