[TowerTalk] radial geometry

Tom Rauch W8JI@contesting.com
Mon, 3 Sep 2001 20:49:38 -0400

> I am burying radials under the lawn so that I can feed the tower as a
> vertical. The tower is a few feet West of the house. I can easily run
> 30-40' radials from tower to the N, NE, E, SE and S but I can not run
> radials from SW through to NW because of the house.
> Questions:
> How much does the radial geometry affect the radiation pattern?
> Any suggestion how to deal with the radials that should be run where
> the house lies (of other than moving the house or tower :-)?

If you can't go through the crawl or basement, just go around the 
house with a heavy buss strap or wire. Pick up on the other side if 
you can.  

Radial geometry mostly affects overall efficiency, NOT pattern. It is 
folklore that radials concentrated in one direction improve gain in 
that direction a noticeable amount. The exception is if you make 
the radials many wavelengths long and very very dense well out in 
the Fresnel (fre-nell) zone.

I remember getting a call to a unstable BC array in Ann Arbor 
Michigan. The pattern was weak in all directions, and unstable with 
moisture changes.

Turned out an engineer who measured excessive FS in the null 
directions removed all the radials in those directions from a multiple 
tower array. The result was FS in the desired directions dropped as 
much as in the directions where he pulled out the radials.

Re-installing the ground system in the null directions brought back 
the signal in all directions, and changing a bad component in the 
phase monitor corrected the original problem. In 1970 dollars that 
was an $4000 mistake.
73, Tom W8JI

List Sponsored by AN Wireless:  AN Wireless handles Rohn tower systems,
Trylon Titan towers, coax, hardline and more. Also check out our self
supporting towers up to 96 feet for under $1500!!  http://www.anwireless.com

FAQ on WWW:               http://www.contesting.com/FAQ/towertalk
Submissions:              towertalk@contesting.com
Administrative requests:  towertalk-REQUEST@contesting.com
Problems:                 owner-towertalk@contesting.com