Message-ID: <m117igN-0002SpC@fwd07.btx.dtag.de>
Date: Fri, 23 Jul 1999 19:00:27 +0200
To: rsgb_lf_group@blacksheep.org
Cc: DK7UY@geocities.com
Subject: LF: Ground systems
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From: "DF2PY" <df2py@t-online.de>
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Hello Lowfers !
In one of the recent postings it was stated,that chicken wire on the ground 
makes no good RF-ground.Well what i got to say about it is not very much 
scientifically researched by myself,but i tried to do it experimentally with the 
probes that were available to me.
I run a two element vertical array on 160m and finally came up with chicken wire 
as the best solution.I measured the current in the radials and did measurments 
in the "near far field",as well as signal readings about 100 wavelength away.
attaching the chicken-wire was far superior to the single wire radials.As far 
as conductivity of my soil is concerned,i am on a waterfront-property and the 
level of groundwater is only 3 feet down,i cant ask for more with sweetwater.Of 
course it is hard to compare as the surface of both is hard to compare.But 
following the basic rules ,You ought to have as much conducting surface as You 
can where the RF-current is high-thats at the feed on the ground for the 
antennas in discussion.Thats exactly where the most energy is dissipated =in 
poor conducting soil and in lossy dielectrics.Additionally in non-ideal 
Inductors-but thats not the issue.
Coming back to LF,i found the antenna current only slightly increasing with more 
chicken-wire.BUT ! The field-strength came up unproportionaly !!
That means the efficiency came up and that is something You don`t see on the 
feedpoint-current.Some get misleaded that way.For newcomers to "antenna-land"
it means that raising input power is one thing,the other is bringing up the 
efficiency,and as the later one is a very complex function of too many factors 
we cannot sufficiently control,the best is to measure the field strength- to 
which i think Dick-PA0SE made a very helpful contribution.In addition i think it 
is good to reduce the amount of lossy dielectric ( soil )in the field,with a 
ground screen on the ground You can achieve that,given that the surface is big 
enough to cancel most of the ground effect from the "original ground ".
sorry for the bandwidth i am taking here,but i guess thats the purpose of this 
forum.I tried to refrain from formulas and " Einstein-type" hypothesis and get a 
fruitful exchange with people started,that know more about it than i do.
   good dx !!      de df2py