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Roy, W7EL wrote:
"When all this is done, I hope that readers come away with some assurance that circuit theory does work and can be applied to antenna problems -- provided that the assumotions made for the components are valid." Yes. And, there is another proviso. The reflected energy must be considered along with the incident energy. Antenna problems are relatives of transmission line problems. Terman wrote of impedance in a transmission line with a reflection: "When a reflected wave is present, the impedance will be alternately greater and lower than the characteristic impedance, as illustrated in Fig. 4-10." This is also true of standing-wave antennas but is complicated by r-f radiation from the antenna. Early in this thread, I gave the example of W5LIT`s mobile antenna which was all coil. It was a bamboo pole wound end to end with wire. At the feed end its impedance was low. Approximately 90-degrees away at the tip end, impedance was very high as indicated by the corona often produced by the high voltage. The current at the tip end was much less than at the feed point. The ARRL Antenna Book shows how this can happen in Fig 6 on page 16-4 of the 19th edition. I admire and appreciate Roy`s experimental verification of antenna speculations and predictions. Until demonstrated, theory is only theory and all such explanations are not necessarily so. Best regards, Richard Harrison, KB5WZI |
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