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Re: [TowerTalk] trees and verticals

Subject: Re: [TowerTalk] trees and verticals
From: Jim Brown <>
Date: Tue, 27 Dec 2011 09:32:56 -0800
List-post: <">>
On 12/27/2011 8:04 AM, Eddy Swynar wrote:
> And in 25 words, or less, explain why."

My last paragraph attempted to do that.  But antennas and radio are far 
to complex to describe their behavior in 25 words or less.  One must 
struggle to get one's mind around the laws of physics. We can do 
relatively simple math to describe the behaviour of a simple antenna in 
free space, or over an ideal earth with nothing in the way, and the 
patterns are pretty and fairly easy to understand.

Trees, rain gutters, buildings, wiring in those buildings, towers, 
feedlines to other antennas, even losses in the earth itself that vary 
from one spot to another, are all complications that are incredibly 
difficult to model mathematically. What I have attempted, and what Doug 
and Roger chimed in to contribute to, are some careful observations of 
how antennas we have built have worked around one set of these 
complications -- trees.

To Doug -- my 160M Tee vertical that works well is more or less in the 
middle of the clearing around my house and shack, which we here in the 
California mountains have learned is critical for survival in a wild 
fire.  The top of the Tee is suspended from a redwood on one end and big 
Madrone on the other.  I have a 170 ft  loaded horizontal dipole for 
160M at 110 ft in that clearing, and when I first had both it and the 
Tee vertical, I spent a lot of time switching between the two antennas 
in contests.  What I learned in that first year of very actively 
comparing them was that on any given path, at any given time, one might 
be better than the other, and it was difficult to predict which would be 
better. BUT -- in the daylight hours (160M contests start at 2PM out 
here), the vertical was ALWAYS at least 10dB better. I found that I 
could consistently work everything I could hear out to about 1,000 miles 
(Seattle, Denver, New Mexico, AZ) before dark, and for a few hours after 
dark, with the vertical, whereas I wouldn't even get "QRZ?" with the 
horizontal dipole for those distant stations. And that's a horizontal 
dipole at 110 ft!

And Eddy -- I've heard you a few times during contests in the morning 
hours, but you don't hear me calling (even though I work a lot of east 
coast stations).

73, Jim K9YC

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