Frank's wrote:
I had always assumed that a NEC model of a perfectly conducting
monopole above a perfect ground would provide the radiation
resistance. For example, considering your antenna of 18.3 m
at 3.62 MHz, the input impedance is 27.5 - j 64.7. The radiation
resistance would therefore be 27.5 ohms. This appears to be
fairly close to your estimate of 25.4 ohms.

If the field strength coordinates were the same for
a perfect antenna model and a real-world antenna
model, would the ratio of the areas under the curves
yield the simulated efficiency of the real-world model?
--
73, Cecil, http://www.qsl.net/w5dxp