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Re: [TowerTalk] Trees and Verticals

Subject: Re: [TowerTalk] Trees and Verticals
From: Jim Brown <>
Date: Wed, 28 Dec 2011 22:45:11 -0800
List-post: <">>
On 12/28/2011 6:18 PM, Jim Lux wrote:
> For a given voltage at the feedpoint, the current in the tree will be
> 1/30,000th that in wire.   The power dissipated is that squared.. or, in
> other words, negligible.
> This is a fascinating observation...

Indeed it is.

> IN other places, we've discovered that trees are like soil (similar
> conductivity and epsilon), and we know that laying an antenna on the
> ground doesn't work all that well.   However, that's the difference
> between half of the space being occupied by the lossy medium and just a
> tree's worth.

When thinking about attenuation in a forest, it should be remembered 
we're talking about a DENSE forest, a lot of big trees relatively close 
together, and some of those studies you've cited are talking about 
jungles.  This is very different from hanging a wire in/near a single 
tree or a few trees.  A very dense forest like mine, or the pine forests 
of the American South East, are somewhat analogous to the lossy soil.

> To compare.. if I put two 8 foot rods into the soil 10 meters apart,

When I've measured resistance between two rods a few yards apart in the 
loamy soil of my redwood forest, the lowest DC R I've seen is on the 
order of 30 ohms.  This is with a Simpson 260.

Thanks for a VERY interesting post, and the digging that's behind it.  
I'll be chewing on it for a while, and I suspect others will too!

73, Jim K9YC

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