I am out of range (Arizona this weekend) for your experiment, but interested. I have carefully measured infrastructure effects (including buried utilities and other utilities), and have coincidentally seen roughly 6km range (at VLF frequencies) in a scenario that is somewhat similar. For what it’s worth I found steep field gradients near 3km-6km (infrastructure and topology dependent) in four directions, and did not have time or RX dynamic range to determine whether these gradients were associated with multi-modal interference nulls, utility decouplers, or simply extinction of the reactive field. I hope to extend my RX dynamic range by ~ 20dB in the near future, and will repeat these measurements (at ranges > 6km) at that time.

Does your infrastructure broaden your signal and/or add spurs? I suppose you can’t know this until your test is underway, but it might be helpful for others to eventually know this, on the chance that some infrastructure resonating off center frequency has a large aperture and could therefore be detected more easily than the fundamental at ranges > 6km*.

At 50V, 1.5A  (~ 33 ohms) do you think that you are losing any current  to undesired paths?

Best of luck on your tests.

73, Jim AA5BW

*  (given your antenna contact separation, it seemed that infrastructure aperture might be significant compared to coupling between your earth loop and the infrastructure, for RX separations > 6km, at which distance the reactive field may be giving way to aperture-dependent quasi-static and radiative field components)

G3MFW has problems posting to the Groups at the moment, I have received the following from him.

I have been experimenting with earth systems for some years. I now use the house water pipes and an array of 11 copper earth rods and buried sheet in parallel, 30 metres away at the bottom of the garden. At 8.9758 (crystal) I pass 1.5 amps at 50 volts RMS. I have made a reception map around Truro, Cornwall, at 1.46Hz bandwidth using a 41 turn horizontal loop on the car roof rack, supplemented by using the same loop on the ground. Ranges vary greatly with topography and earth conditions, but are up to 6 Km with buried utilities assistance.

I will transmit this Saturday, 21^st Dec, from 9.00 to 10.15 am using QRSS 3 with endless dashes. I would be most grateful if you would report any reception using narrow bandwidths. I must be exciting several square kilometres of buried utilities – surely SOMETHING must be radiated! I can repeat the test at any time upon request.

Harry Woodhouse, G3MFW