Good day Joe,
Your test setup is as suspect as your numerical model. Nothing
personal, this is true for anyone. They should be made as similar as
possible, if your physical patch is over a small ground plate above
real earth, that's the way you should model it. Details of the feed
have a large effect on the input impedance. Your coax should
terminate on the lower ground plane and only the bare center wire goes
up to the patch. This makes it look more like the wire segment(s) you
have to use in NEC. You should have several segments in the modeled
feed wire, with the source near the ground plane. You should also
compare both results with the radiation resistance given in texts on
antennas. When doing this comparison, do it on the basis of
admittance rather than impedance. The size of the feed hole for the
coax has a large effect on the shunt capacitance, but much less on the
shunt conductance.
Good luck,
Doug Miron
Received on Thu Dec 21 2000 - 03:59:03 EST
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