Don Wilhelm wrote:
Jack,
Yes, connecting a measureing instrument directly to an antenna can be
troublesome if there are strong broadcast stations in the area or other
sources of signals that can fool the instrument.
Zack Lau addressed that situation in a Technical Correspondence article in
QST a while ago - his answer was to measure the antenna indirectly with an L
network - the L network provides selectivity - adjust the L network to
provide a 50 ohm match, then remove it from the antenna, terminate what was
the measurement side with 50 ohms and measure the side previously connected
to the antenna.
Sounds like a sane way to approach it to me.
I'm not sure of the reasoning, but he also said that if you do this, you
need to reverse the sign of the reactance that you get when you measure
the network.
--
73,
Vic, K2VCO
Fresno CA
http://www.qsl.net/k2vco
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