On Fri, 09 Dec 2005 11:45:32 -0800, Roy Lewallen
wrote:


2. The power intercepted by the matched dipole in the problem recently
posed by Reg is approximately 3 mW, not 12. The EZNEC calculation I
described, which does not use a plane wave source, is correct. The same
result can be obtained with NEC by using two antennas as in EZNEC, or
with a 212 V/m (peak, equal to 150 V/m RMS) plane wave source which
produces a 300 V/m RMS field at the loaded antenna.

To a certain extent, this comes back to a decision about whether
ground reflection contributes to the received power, and you are
saying that NEC assumes it does under plane wave excitation in
presence of a ground plane.

In "running the numbers", I note that the radiation resistance
indicated by NEC for a short dipole in free space is quite different
to that predicted by Kraus for a dipole with uniform current,
(Rr=80*pi()**2(L/Lambda)**2)!

Owen
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