[TowerTalk] wierd antenna question
jimjarvis at verizon.net
Sat Aug 12 12:14:19 EDT 2006
...this was the multiband fan dipole, one side of which fell across tower
snip " I still do not see how it could have been working so well with the
driven side shorted out on the guy wire. Joe KI4ILB"
Joe, you didn't say what frequency you were operating on, or what distance
the contact was over, or where the antenna fell on the guy.
Suppose it laid across the guy 17' from earth, and you were talking on 20m.
That's 1/4 wave up...and the guy would have radiated due to the current
in it. You DID say you had to retouch the tuning, as I recall. Are they
grounded at their anchor points? If not, the whole thing may have been
and your antenna was simply unbalanced to some degree. Missing 6-10dB due
a mismatch won't matter much if you've got a solid path to begin with.
In addition, you didn't say how long your feedline is, or if it's coax. (or
forgotten). The mismatch caused by the drooping antenna would result in the
feedline behaving like an impedance transformer....so what the rig
might not have seemed to have changed very much.
jimjarvis at ieee.org
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