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Richard Harrison wrote: Roy, W7EL wrote: "So tell you what. If you`ll pull out your equations and calculate the expected current difference, I`ll replace the coil with one of 100 ohms reactance and remeasure." The challenge was directed to Cecil, but anyone can respond. The current is a function of position along the antenna. Distribution is cosinusoidal as Yuri said. That's right. The distribution is the result of the superposition of the forward and reflected currents. It's basically just one quarter of a cycle of the standing wave pattern. When the electrical length of a loading coil represents any significant fraction of the length of the antenna, the superposition of forward and reverse currents at each end of the inductor will result in different values. The difference is due to the phase delay through the loading coil, as Cecil has explained. Delay is an unavoidable artifact of propagation through wire - whether it happens to be wrapped into a coil, or not. 73, Jim AC6XG |
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