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Re: [TowerTalk] Ground radials- the long and short of it

To: "Scott Fike" <>, <>
Subject: Re: [TowerTalk] Ground radials- the long and short of it
From: "Tom Rauch" <>
Reply-to: Tom Rauch <>
Date: Fri, 22 Oct 2004 06:09:48 -0400
List-post: <>

There are a lot of myths and a great deal of misinformation
out there about radials. That's mostly because good radial
systems involve work, and we all hate to work.

>   Do ground radials have to be electrically the same
length as the main
> vertical radiator element?

No. Radials needs to be as many as long and as straight and
evenly spaced as possible. If they are close to ground or on
ground, you need 20-30 0.2 wavelength long to have a really
good ground. About 50 or 60 radials is nearly perfect.

>   Example: Take a 1/4 wave 80 meter hamstick stuck
vertically in the ground.
> An 80 meter hamstick is physically about 6' tall but has
about 60' of wire
> wound hellicaly around its 6' core insulator rod. Would it
be better to make
> my ground radials using hamsticks (with their 60' of wire
but physically
> still 6' long overall) or can I use 6' pieces of wire to
match the hamsticks
> physical overall length or should one string out 60'

The general rule is the better the antenna, especially if it
is short, the more radials you need to obtain nearly maximum

The Hamstick is such a poor antenna, there is no point
busting your butt with radials. If the antenna haqs 20 ohms
of loss, it makes no sense at all to try to get a ground
system with 2 ohms loss. You'd never notice the change in

You should string out longer radials, perhaps 40 feet or
more long, but even 10 or 20 and the antenna loss would
become the main limitation.

Keep in mind no matter what you do an 80 meter Hamstick is
going to have VERY poor efficiency. The bulk of your
transmitter power will be heating the antenna up. No point
breaking your back installing an exceptional ground system
when the antenna dominates the system loss.

>   Some books I've read say:  ".... make the ground radials
1/4 wavelength
> long to match the main 1/4 wavelength long vertical
element". Other books
> and sources say: "..... just make the ground radials as
long as you can to
> fit in the availible space in your yard".

The second statement is correct, within reasonable limits.
You should use as many radials as straight and long as
possible. 50 or 60 straight evenly-spaced radials nearly l/4
wl long makes a nearly perfect ground system under almost
any circumstance. The shorter the antenna, the more
important the ground system becomes.

There is no reason to use a nearly perfect ground system
when the antenna is very poorly designed, however. That's
because the loss resistance of the antenna wastes most of
the energy. If the antenna loses 90% of the power and the
ground system only 10%, who cares if you make the ground
system perfect? No one would notice.

73 Tom


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