[TowerTalk] Fwd: Trees and Beams

[hanslg at aol.com]

 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 at aol.com
To: towertalk at contesting.com; wb0m at 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 at 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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