Topband: Trees (not the N6TR kind)

[Jim Brown]

On 1/1/2013 7:35 PM, Tom W8JI wrote:
> That was a rather dense stand of trees.

There ARE such things -- my redwood forest is quite dense -- I'd guess 
more than 100 of them, plus a lot of smaller ones, in 8 acres, ranging 
from about 100 ft to more than 175 ft, and from 2 ft to 6 ft in diameter 
at the base. Traveling thorough the SE US,  I've seen pine forests that 
were pretty dense, and this is where the comments I'd cited from cell 
phone systems installers had come from.  Think about WA6NMF's off the 
cuff "-3dB per tree" in that context.

> A few trees a reasonable distance from a LF antenna are not going to 
> do anything observable. A single tree at 2 GHz can mean 20-40 dB. It 
> has nothing to do with resonance, but rather how much the electric 
> field is killed by the resistors sticking up in the air. 

I think there may be merit in Guy's observations that a lot of tall 
trees can put a big dent in the performance of an HF vertical.  My 
attempts at making verticals work here above 160M have been 
spectacularly unsuccessful. I should have noted that in my earlier post.

73,