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TopBand: an elevating experiment

To: <topband@contesting.com>
Subject: TopBand: an elevating experiment
From: w8ji.tom@MCIONE.com (Tom Rauch)
Date: Sun, 15 Mar 1998 08:25:14 +0000
To: <topband@contesting.com>
> Date:          Sat, 14 Mar 1998 13:34:01 -0500 (EST)
> From:          CQ K8DO <CQK8DO@aol.com>

Hi Denny,

As Eric pointed out, and I keep pointing out, changing the radials 
does NOT affect wave angle. It's part of Hamlore and common but 
incorrect rumor that they do.  I would add two exceptions, however:

1.) If the radials are radiating and acting like antennas that 
contribute radiation in the farfield, they certainly affect 
radiation pattern.

2.) If the radials are VERY long, several full wavelengths, then they 
affect pattern. 

In any case, we are talking about under 1/2 wl long systems that have 
minimal radiation. 

> I am having a problem parsing the above paragraph... Did  64 ground radials
> have a 5 dB advantage over 4 elevated radials?...

Absolutely, but let's say "about 5 dB or so". Then it is true not 
only here in my tests, but also in measurements made at WVNJ 
radio. At WVNJ radio the difference was larger when operating with a 
directional pattern, because the particular directional array they 
used had some very concentrated currents in and around some elements.

> If they did and if the 4
> elevated radials had a "few dB" advantage at the 16 ground radial point,
> where the the break even point occur , in terms of the number of ground
> radials compared to the 4 elevated radials?

At four radials, the elevated system had 1.2 dB advantage but was 
still  4.3 dB down from 60 radials.

At 16 radials, elevated radials had only a 1/2 dB advantage, and 
were 2.4 dB down from 60 radials.

At 32, the difference was less than instrument tolerance, and about 
.7 dB down from 60. 

At 60 radials the ground mounted system measured slightly stronger, 
but that could have been instrument tolerance.

With a shorter vertical, or a close spaced directional array, the 
difference would be greater from best to worse.

73, Tom W8JI
w8ji.tom@MCIONE.com

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