Topband: Loop on the ground as a counterpoise

[Chris Moulding]

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