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Resonant condition
On Jun 4, 4:40*pm, Roy Lewallen wrote:
Richard Fry wrote: The equation for the radiation resistance of short antennas given in that paper is independent of the resistive losses in any loading coil or r-f ground system. And the same fundamental equations are used by modeling programs. The problem is that interaction between the antenna, an abbreviated ground system, and the Earth can modify the radiation resistance as well as adding loss resistance. Could you please explain why, if the same fundamental equations given in antenna engineering textbooks and I.R.E. papers are used by modeling programs, the results of their use do not always support each other very well? If it is accepted that the radiation resistance of a short monopole is independent of the loss resistance in the loading coil and r-f ground either alone or together, then what is the basis for the variation in radiation resistance that you report? BTW, the equations in the Carl Smith paper I referred to earlier in this thread produce a radiation resistance of 0.113 ohms for a 1.65 MHz, 9.84' (3-m) x 0.25" OD, base driven monopole -- which is not _hugely_ different than the values calculated by EZNEC. RF |
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