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Re: Topband: Forestry Effect on Antennas and Radials (Charlie Young)

To: <topband@contesting.com>
Subject: Re: Topband: Forestry Effect on Antennas and Radials (Charlie Young)
From: "Craig Clark" <jcclark@myfairpoint.net>
Date: Sun, 4 Jul 2010 16:31:57 -0400
List-post: <topband@contesting.com">mailto:topband@contesting.com>
>From your email

At my QTH in NJ I have the capability to mount a 500-foot,two-line,
reversible Beverage running NE-SW. 
However, I am hesitant to undertake this project because the antenna would
be entirely in the woods.  These are not dense woods, for deer now consume
every sapling.  Therefore, there are only trees of from 25 to 90 feet high.


>Sounds like my woods here in NH. 

Because of the deer, the Beverage would have to be at least six feet high.

>I'd opine you want to be at least 8'as a buck's rack can extend higher than
6'. You also get the antenna out of the reach 
>and possible damage from hunters and casual walkers in the woods. 
 

Two questions: 
1)  Would the antenna, 500 feet long, still be reasonably effective at that
height? 

>see above but yes, it would work

 2)  Would it be able to receive an adequate signal in the described woods?


>AB-SA-LUTELY! My Beverages have been running in my woods for 30 years and
they work. I have used single wire Beverages and >am now using a KD9SV two
wire WD1A designed antenna; two wires give me NE-SW and NW and SE. Here's a
link to a site with a great >paper http://www.elisanet.fi/oh3xr/ Look for
the PDF reference.
  

For the record, I already notice that 16 in-ground radials each 160 feet
long and running entirely in the woods, produced very little change in the
performance of my vertical transmitting antenna when they were added to an
existing field of 22 radials, 60-120 feet long, installed in an open lawn
area.

>how long are the radials? That might hold the key to your answer. I have
close to 10,000' under my quarter wave vertical >which is ~~300' from the
station in the woods....surrounded by trees. Big trees
 

I have tentatively concluded that the woods to the north are absorbing the
radiation from my transmit antenna, and therefore the same kind of woods,
lying to the south and east but more than 100 feet away, will seriously
diminish the signal reaching the Beverage.

> How have you come to this conclusion? My transmit antenna is deep in my
woods surrounded by trees and it works. Trees >become a problem at higher
frequencies such as 400-900 MHz but at 1.8 MHz they are for all intents and
purposes invisible.
>Search the archives and you'll find this has been debated several times.   

Craig


Craig Clark K1QX
Radioware
PO Box 209
Rindge NH 03461
603 899 6957 
www.radio-ware.com


 
 


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UR RST IS ... ... ..9 QSB QSB - hw? BK

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