[TowerTalk] Beverages and Trees
Thu, 9 Mar 2000 01:12:18 -0400
I don't know if John is talking about any other thing than the atenuation
effects of a electromagnetig field,but taking in count that the
Er(permitivity) of dry wood is 1.5-4 and assuming that isn't completly dry
and we take a mean value of 2.5,the skin dept(how far the wave has
penetrated inside the wood when it is atenuated 37%) is about 270m.So unless
you are using a 270m long wood pole the wave won't atenuated almost
anything.Now certainly this pole will have other effects like changing the
impedance that the beverage see to the ground(is suppose to be lower) but
this is beyond that scope of my knowledge(PUPR doesn't have the best
Electromagnetic course yet hi hi).
----- Original Message -----
From: alsopb <email@example.com>
Sent: Wednesday, March 08, 2000 2:12 PM
Subject: [TowerTalk] Beverages and Trees
> I was re-reading the ON4UN Low Band antenna handbook and ran across a
> statement I need more info on. This quote is from the section titled"
> Location of the Beverage"
> "Just as it is not recommended to put up vertically polarized antennas
> between tall trees, it is not a good idea to run a Beverage antenna
> through the woods"
> Would somebody please explain this. It was my impression that trees
> are fairly transparent to RF at lower frequencies. What is the real
> effect and its magnitude?
> What about the practice carried out by some of using galvanized
> staples to attached galvanized wire bevrages to tree supports? I see
> that even ON4UN attaches beverages to bamboo poles.
> 73 de Brian/K3KO
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