Jim,
I believe that the key question for you is whether your vertical is "ground
mounted" or elevated mounting ?
Assuming that it is ground mounted, radials which are placed on or below the
ground's surface are detuned by the ground, therefore, the length is not
critical. Get as many radials down as possible, each as long as possible.
Rule of thumb is that a minimum of 20 fifty foot long radials will get you
going in the right direction. Additional grounding through 8 or 10 foot
long ground rods needs to be in place as well for both lightning protection
and as part of the RF ground system. Again, the rule of thumb is a minimum
of 1 ground rod, however, 4, placed around the base of the antenna would be
ideal.
Hope this helps.
73,
Dave, K2DP
----- Original Message -----
From: "Jim Lux" <jimlux@earthlink.net>
To: <towertalk@contesting.com>
Sent: Saturday, April 30, 2011 10:19 PM
Subject: Re: [TowerTalk] Number of radials and length to install ??
On 4/30/11 4:32 PM, W1JCW wrote:
> Hey guys -
>
> I have a 32' vertical I'm installing.
>
> I searched the post files but didn’t see a related msg reply.
>
> What would be a good number of radials to put down and what lengths for
> 80m - 10m ??
>
> I know there are many schools of thoughts and theory so I figured I would
> see what I get
> for replies.
>
> Thanks.
>
> 73-
> W1JCW
> John
> _______________________________________________
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>
Assuming you mean laying on the ground or buried
Radials longer than the height of your vertical (i.e. 30ish feet) are
probably past the point of diminishing returns.
More radials are better.
twice as many radials half as long is probably better.
30-60 radials is probably the point of diminishing returns.
so, let's say, you have a 500 foot spool of wire. you could do 16
radials 30 feet long.
or you could do 30 radials 16 feet long.
My gut feel is that the latter is better. The current at the base of a
vertical is higher, so the current density in the soil near the base is
higher.
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