[TowerTalk] Wires in trees

Jim Brown jim at audiosystemsgroup.com
Tue Jan 23 01:37:34 EST 2018

As it happens, there's an interesting technical article in Feb 2018 QST 
that landed in my mailbox today.

The executive summary -- trees can cause considerable loss in vertical 
antennas. The closer the wire is the tree, the greater the loss. More 
trees => more loss.

I live in a dense redwood forest. Except for 160M, where all my antennas 
are verticals, all my antennas for bands above 160M are horizontal, 
either dipoles or Yagis. I've tried verticals on HF, and all perform 
miserably. On 160, the verticals outperformed a horizontal dipole at 120 
ft by a lot, but the article predicts that the trees are sucking up a 
lot of their radiated RF, and my on-air experience suggests that's 
probably right.

The article does not address horizontal antennas and trees.

73, Jim K9YC

On 1/22/2018 10:24 PM, Steve Boone wrote:
> This is a topic that I have never seen addressed and Google has not
> revealed any similar situations:
> I am installing a quarter wave, 160m inverted-L between a 40' Ponderosa
> Pine and my tower. The first 30' of the antenna will run parallel to the
> tree trunk and through the branches. I am using copper coated wire for the
> element. I have four elevated radials at the 10' level.
> My concern is whether I need to worry about contact between the wire and
> the tree. With the very low humidity that we get during Colorado summers, I
> am wondering if there is a fire danger here.
> I will be running a 1.5 kW.
> Thanks,
> -Steve, W7WM
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