I had a LW running though some tree branches. Found that it was impossible to
get a stable SWR (Used a tuner to get the "right" impedance at the trx end).
Only after removing the offending tree and have about 5 -7 feet to the next
tree did I experience stable SWR readings.
I am operating 160 - 20 meter on the LW. I believe if I have more than 4 feet
clearance everything seems OK.
I guess as long as you have clearance so the beam don't get tangled in the tree
it should be OK.
best 73 de Hans -N2JFS
-----Original Message-----
From: K7LXC@aol.com
To: towertalk@contesting.com; wb0m@flashdog.us
Sent: Mon, Jul 13, 2009 3:28 pm
Subject: Re: [TowerTalk] Trees and Beams
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
**************Looking for love this summer? Find it now on AOL Personals.
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