Hi everybody and happy new year .
I have what I think is an interesting antenna riddle . I have some receive
antenna verticals (4) that are selected by relays in pair and the pair is fed
back to the shack to a phasing boxing .Each antenna is AL tubing about 30 feet
tall, base loaded with an inductor and a resistor very much like ON4UN has for
his 4 square receive array .There is a 1 to 1 balun between the antenna and
the feed line . The tubing is insulated with an eight inch length of pvc pipe
from the 4x4 that supports it .The overlap between the tubing and the 4x4 is
about eight inches as well . I was doing some testing today and discovered that
touching the 4x4 at the top caused the swr to increase from about 1.2 to 1 to
1.7 to 1 . The lower on the 4x4 I touch the less the effect . I am only moving
my finger a fraction of an inch and my hand not at all when this happens .The
feed lines are disconnected when this is going on .There is no dc continuity
between the antenna and any mounting hardware or th
e post .I disconnected the base loading and put the analyzer on it and it is
resonant at about 8 mhz and touching the post causes no change with this setup
. There are eight 30 foot radials laying on the ground and a 2 inch wide copper
strap about 3 foot long in the hole that the 4x4 is in .
What is going on here and should I make an effort to limit the coupling between
the 4x4 and the antenna?
73 , Glenn WW4B
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Topband Reflector
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