Fw: Re: [TowerTalk] Compromise Vertical antenna ground system?

n4kg@juno.com n4kg@juno.com
Sat, 28 Sep 2002 21:32:36 -0600


Here is what W8JI had to say on the subject 2 years ago.

Tom  N4KG

--------- Forwarded message ----------
From: "Tom Rauch" <w8ji@contesting.com>
To: towertalk@contesting.com, "Avila, Edward" <EAvila@caiso.com>
Date: Mon, 21 Aug 2000 20:48:49 -0400
Subject: Re: [TowerTalk] Compromise Vertical antenna ground system?


> Well, my problem/question: I have very little room to run horizontal
> radials from the base of a Butternut HF2V I'm thinking of installing on
> the ground.....at the most 10-15' in some directions, which is a little
> shy of 1/4 for 80 meters!  Any suggestions for a compromises ground
system
> that will make the best of what I have to work with? Would more ground
> rods help? More radials, even though they will be electrically short? 

There are always points of limited return in any design. Radials are 
no exception.

The optimum number of radials for any radial length occurs when 
the open end of the radials is .025 to .05 wl apart. You should do 
this on the highest band you are seriously interested in.

The point of diminishing returns for radial length is when the radials 
are about .2 wl long on the lowest band you are interested in. 

So if you are interested in 40 and 80 meters, the open ends of the 
radials should be no more than 3- 1/2 feet apart and the radials 
need be no longer than about 55 feet long.

Wrapping a radial around to add length generally does nothing 
worthwhile.

So in the short directions you need fewer radials than in the long 
direction.

What I do is make a measuring line between two stakes. I then 
"leap frog" the stakes around the perimeter as I pull radials from 
the center point to each stake.

A ground screen will generally only help when you have less than 
30 or so radials. With more than 30 or so radials, a ground screen 
is a waste of time.

A ground mounted vertical with a fair radial system is almost 
always much better than a "no ground" vertical...especially on 80 
and 40 meters.

     
73, Tom W8JI
w8ji@contesting.com



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