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Reg:
[snip] For calculating convenience, we assume the radiation resistance, Rrad, is uniformly distributed along the length of the wire and is 140 ohms which has been calculated from its dimensions. It only has two - Length and Diameter. But for a half-wave dipole it is always about 140 ohms. Wire diameter has a relatively small effect on Rrad. [snip] Reg, in your model, is your *assumption* "for calculating convenience" that radiation resistance is uniformly distributed along the antenna structure, i.e. the transmission line that represents the antenna in your model, supported by any theory or is it just a mathematical *fit* to the data? For example, one could *assume* literally any analytic distribution of radiation resistance along an antenna's length, for instance sinusoidal, catenary, exponential, triangular, etc... and come up with a value/function for that particular distribution that has the equivalent effect of a lumped value placed at the antenna feedpoint. What is so unique about uniform? Why do you think *uniform* is any better than any other distribution of Rrad? I have no axe to grind here, just curiosity... Best Regards for the New Year. -- Peter K1PO Indialantic By-the-Sea, FL. |
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