Topband: Loop on the ground as a counterpoise

[donovanf at starpower.net]

Chicken wire laid on the ground makes an excellent RF ground 
for Beverages and other antennas requiring a good RF ground. 


73 
Frank 
W3LPL 

----- Original Message -----

From: "Nick Hall-Patch" <nhp at ieee.org> 
To: "Chris Moulding" <chrism at crosscountrywireless.net>, topband at contesting.com 
Sent: Tuesday, May 5, 2020 6:40:47 PM 
Subject: Re: Topband: Loop on the ground as a counterpoise 

Your "loop ground" made me recall the US military "surface wire 
ground", Chris, which was (is?) used for mobile applications, and is 
often configured as a loop of wire, held down by metallic stakes, 
around a vehicle. 

Upon looking more closely, 
https://apps.dtic.mil/dtic/tr/fulltext/u2/a277285.pdf seems to be 
much more concerned with its utility as safety grounding, especially 
concerning lightning, so I don't know if any research was done 
concerning its effectiveness as a signal reception ground. 

I have used something like the "surface wire ground" on our coastal 
rocky "soil" (very resistant to ground rods) when using Beverage 
antennas. It seemed to work fine for matching transformer use, but 
not much use for termination ground. To be fair, ground rods don't 
particularly work here either for termination grounding. 

73 

Nick 
VE7DXR 


At 08:57 2020-05-04, Chris Moulding wrote: 
>I've developed a High Z Antenna Amplifier for 160m and other HF use 
>as previously mentioned on the list. 
> 
>Usually these would be used with a ground rod and 5m vertical element. 
> 
>With the lockdown it's not possible to nip to the shops for a ground 
>rod so I looked at supplying a 10m wire as a counterpoise. 
> 
>At home and the workshop I have Loop on the Ground antennas from 
>previous antenna experiments so I also tried using these with both 
>ends of the loop connected to the amplifier ground terminal. 
> 
>On testing this gave significantly better signal to noise ratios 
>than using a ground rod or a single wire counterpoise. Checking with 
>a SDR receiver I could see that the usual local VDSL internet hash 
>had disappeared. 
> 
>Both loops on the ground are 3m or 10' square. 
> 
>I've also tried it using a G7FEK vertical antenna at home with two 
>3m or 10' square loops on the ground with similar results seeing 
>much reduced local noise compared with the ground radials I had 
>before. Topband Dx might be a possibility for me now. 
> 
>I've never seen this mentioned in ham magazines before and I can't 
>find anything with an internet search. Usually I find that all my 
>good ideas have already been thought of 50 years ago. 
> 
>I suspect that the RF voltage in the loop counterpoise is much 
>reduced over the voltage at the end of a radial wire reducing noise 
>pickup in the radial system. 
> 
>I would like to model the loop on the ground counterpoise in a 
>modelling tool. I use 4NEC2 but only have access to NEC2 so wires on 
>the ground don't model correctly. 
> 
>Is there any one out there with access to suitable software that 
>could model it for me? 
> 
>73, Chris G4HYG 
> 
> 
> 
> 
> 
> 
>_________________ 
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Nick Hall-Patch 
Victoria, BC 
Canada 

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