You can easily see the effect of a tree (such as a tall Pine) if you drop a
vertical wire a few feet from the tree. A common scenario is for an
Inverted L or a top loaded Tee, where the vertical wire is not very far from
the tree. There is a noticeable effect on resonance, and bandwidth,
implying a lowering of the Q-factor of the antenna.
I have used such antennas for years and they work fine, but I have never
done any scientific testing to try to determine if there is any signal
degradation compared to a pristine vertical out in an open field.
I would imagine that there is a difference, but how much of a difference I
can't say.
That said, I would not recommend feeding the tree rather than the wire.
------------------ Wes Attaway (N5WA) ------------------
1138 Waters Edge Circle - Shreveport, LA 71106
318-797-4972 (office) - 318-393-3289 (cell)
Computer Consulting and Forensics
-------------- EnCase Certified Examiner ---------------
-----Original Message-----
From: towertalk-bounces@contesting.com
[mailto:towertalk-bounces@contesting.com] On Behalf Of Dan Zimmerman N3OX
Sent: Sunday, April 26, 2009 1:42 PM
To: towertalk@contesting.com
Subject: Re: [TowerTalk] trees as antennas
> Many years ago, Electronics magazine had a picture of an experiment to
> use a tree as a vertical antenna. The RF was coupled to the tree with an
> air core toroid. It looked like a coiled spring, possibly 6 inches in
> diameter,wrapped around the tree at about 3 or 4 feet above ground.
Here's one online:
http://w5jgv.com/tree_antenna/index.htm
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