In a message dated 7/13/2009 12:02:17 P.M. Pacific Daylight Time,
towertalk-request@contesting.com writes:
> Does anyone have any guess on what would be the minimum distance from
the branches and leaves and from the trunk of a tree to avoid major
disruption of a signal from a beam antenna up about 30 feet? The tree
is a silver maple about 50 feet high.
What's a "disruption"?
You've got 2 considerations: electrical and mechanical.
Electrically if it's for HF, leaves and such don't seem to exhibit any
negatives. For VHF and up, there is probably some signal loss as it goes
thru wet leaves, trunks, etc. I don't know what the magnitude is but I
suspect it's slight.
Mechanically any rotatable antenna should be mounted at the top of the
topped tree in the clear so it'll turn. At that point you're above any
branches so it's a moot point.
You should leave some branches at the top to keep drawing sap up but
they do grow and you'll need to do some pruning every 3-4 years to keep
those little sucker branches from stopping the antenna dead in its tracks.
It's
amazing how much force they can exert.
Cheers,
Steve K7LXC
TOWER TECH
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