> With a series fed vertical on a base insulator, you should be able to
> disconnect the antenna, leaving the mast floating (if it is 1/4
> wavelength or less), and compare the noise in the rx antenna. If
> there is coupling, the noise should increase when the vertical is
> connected to the matching network.
While it is true that disconnecting a 1/4 wl vertical from anything
else will reduce re-radiation substantially, the noise test described
above can not prove anything in many (or most) cases. It is possible
to have a significant deterioration in receiving capability and hear
absolutely no difference in noise in a test without the desired weak
signals present, and the system can actually remain untuned or have
less deterioration when something is attached to the vertical!
How the system reacts is determined by many things, including the
impedance presented to the vertical by whatever is connected to the
base of the vertical. That would include not only the matching
network, but everything connected downstream all the way to the
equipment in the shack. Everyone's antenna system will be different
also, as will the direction and distance of noise sources.
This is almost certainly why we are seeing different conflicting
opinions. There are different answers based on what every individual
they have observed (or think they have observed). There is no single
correct answer, except to keep the antennas as far apart as possible.
73, Tom W8JI
W8JI@contesting.com
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