Who knew that 2 months stuck on-the-road for work followed by holiday projects and other tangents could put such a dent in this topic?!
Anyway, we have finally been able to coordinate a good propagation test this weekend using a combination of overland and underground setups.
Upcoming test is universally on 160m band, specifically 1.86mc.
Adrian Marsh (UK)
Copper irrigation piping ground, can be irrigated with water to significantly lower impedance
2-coil and 3-coil extremely well balanced tuning
1.5kw+ transmit capability
Griffin Brock (Pasadena, CA)
2ea 52gal buried steel drum barrels (optionally filled with water)
2-coil and 3-coil setup
400w transmit capability
Hakasays Telluric site (Southern California, ~120mi from Griffin)
Sheet aluminum in saltwater ocean ground
Single coil extra (optional impedance matching transformer)
60w transmit capability
Hakasays Transverse site (Southern California, ~120mi from Griffin and ~5mi from telluric site)
Vertical 10-80m antenna to 24/7 SDR
Simple copper rod ground
Unattended (used to gauge transverse signal)
Adrian's is the most advanced and precise preise structurally, as he has decades experience with such apparatus. But it's a hail-mary shot as the ground currents required for intercontinental comms may be in the hundreds-of-amperes (note the use of amperes here and not watts!).
Griffin has a middle-ground setup, but more transmit capability than the impromptu test we performed last year.
Mine is the simplest due to logistics issues, but is of a configuration that Eric Dollard stumbled on in the 70-80's. The vertical SDR should also serve as a nice baseline to compare overland and underground propagation.
If we get a strong signal with one and no signal with the other, that would be strong evidence to a different propagation mode taking place.
Depending on time+conditions, we may also be able to take advantage of online SDR's scattered across the planet to help gauge overland transverse propagation. Ideally we would all have AM radio station quality ground with <1 ohm system impedance throughout, but, such is life.
I am happy to answer any technical questions, and can forward any Q's to Griffin/Adrian if anyone has questions about the details of their setups.
"An overly-skeptical scientist might hastily conclude by scooping and analyzing a thousand buckets of ocean water that the ocean has no fish in it."