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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