[TowerTalk] re Radials

hasan schiers schiers at netins.net
Fri Jun 16 09:52:44 EDT 2006

Actually, they can be MUCH shorter than .22 wl, as long as you have enough 
of them. Many more shorter is quite a bit better than many fewer longer.

There are free programs by G4FGQ, RADIAL2 is the name I think, but just 
google G4FGQ and you will get to his site and free downloads. The radial 
program is a good one and answers all the questions being raised. It lets 
you manipulate number/length/freq and ground characteristics to show 
efficiency. VERY HANDY!

For any given band (40,80,160), if I were in a hurry and wanted the best 
efficiency for the time invested, I would put down 16 50' radials as evenly 
spaced as possible. Lay them on the ground, secure with lawn staples. Over 
reasonably good soil in the first place, you will get > 70% efficiency.

I ran a bunch of measurements on radials starting with 0,2,4, up to about 
26. (I laid them out 2 at a time), measuring both 2:1 vswr bandwidth and 
feedpoint impedance (at the actual feedpoint, not in the shack). They were 
all around 50 to 60' and the band was 80m. I got 90% efficiency at 26, and 
had over 70% at 16. Even 8 was not embarassing.

2:1 vswr bandwidth DECREASES with increasing efficiency, as it should.

Feedpoint Z dropped from near 70 ohms to 29 ohms going from 0 to 26 radials 
(theoretically perfect for the antenna in question was 26 ohms...an Inverted 
L of 42 x 25 ft (height, length). The 70 ohms originally measured with no 
radials showed 44 ohms of ground loss (44 + 26 = 70), an efficiency of 37%. 
The final value at 26 radials was 26/29 or 89.6% efficiency

I have enough wire laying around to do about 16 more radials of similar 
length, (and a nice DX-Engineering ground plate to tie them to), so I should 
end up with 52 radials. I would GUESS I might get to 93% or so by adding the 
remaining radials.

Again, all insulated #14 THHN wire, laying on the ground, lawn stapled into 

The data I got is completely consistent with the ARRL publications that 
describe how to get minimum loss for a given wire length available, as well 
as with G4FGQ's program. I do think Reg's program is a bit optimistic, but 
it points one in the right direction. I have full faith in the studies 
published in the ARRL Antenna Handbook on how to optimize a radial field, as 
my actual measurements agree very strongly with the article.

Hope this helps ya.


...hasan, N0AN
----- Original Message ----- 
From: "Bill Coleman" <aa4lr at arrl.net>
To: "Dave Tipton" <dave at lodave.org>
Cc: <towertalk at contesting.com>
Sent: Thursday, June 15, 2006 8:45 PM
Subject: Re: [TowerTalk] re Radials

> On Jun 14, 2006, at 9:46 AM, Dave Tipton wrote:
>> Where it gets wierd, is that when you bury the radials, you can get
>> away with much shorter runs, primarily because 4 or 5 radials 20
>> feet long, will actually couple to ground nicely if buried.  No
>> need for full 1/4 wavelength radials if they're under ground.. It
>> all gets muddled pretty quickly once their an inch under the surface.
> I don't think that 4 or 5 20 foot radials are going to be a terribly
> effective groundplane for a 160m vertical.... Even if you bury them.
> True, the far ends of the wire do less and less "work" of a ground-
> mounted radial system. If you had 60 1/4 wave radials and 60 1/2 wave
> radials, the 1/2 wavers would be slightly more effective -- but only
> slightly - perhaps a fraction of a dB. So, was it worth using twice
> the wire?
> With ground-mounted radials, .22 or .20 wavelength radials will be
> nearly as effective as .25 wavelength, especially if you use 20-30 or
> more.
> Bill Coleman, AA4LR, PP-ASEL        Mail: aa4lr at arrl.net
> Quote: "Not within a thousand years will man ever fly!"
>             -- Wilbur Wright, 1901
> _______________________________________________
> _______________________________________________
> TowerTalk mailing list
> TowerTalk at contesting.com
> http://lists.contesting.com/mailman/listinfo/towertalk

More information about the TowerTalk mailing list