[TowerTalk] modeling compare: 80M, 2EL vs 4SQ

[john at kk9a.com]

If you are going to go though the trouble of burying a complete ground
system, why use elevated radials?  It does not make sense to me to do
both.

John KK9A


To:	towertalk at contesting.com
Subject:	Re: [TowerTalk] modeling compare: 80M, 2EL vs 4SQ
From:	"Joe Subich, W4TV" <lists at subich.com>
Date:	Tue, 17 Mar 2015 15:49:27 -0400


On 2015-03-17 2:26 PM, john at kk9a.com wrote:
If using elevated radials, I see no point in a buried ground system
unless they went well beyond the elevated radials.

It really depends on the degree of screening provided by the elevated
radials and the distance in wavelengths the elevated radials are above
the ground.  If the screening is minimal (as is the case with two or
four radials) and the distance from ground is small (< 1/8 wave), a
dense ground screen can significantly reduce losses in "bad" soil.

Old studies done for the US military show "losses in the dirt" increase
at an accelerating rate as the "ground plane" moves below 1/4 wave.
Even the vertical dipoles (center fed half wave) at WWV had substantial
ground screens to reduce the losses close to the antennas.

Unless I was prepared to install a radial system that extended .4
wavelength beyond each element in an array, I would not use fewer than
6, preferably 8, elevated radials per element to minimize losses in the
soil.

73,

   ... Joe, W4TV