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For
our garden sized antennas I think that resonating a wire is completely
impractical at these frequencies. What I intend looking at, (if a 9kHz NoV
ever happens :-( is something like a ground loop. I'm basing
the idea on the US Submarine comms experience at ELF / ULF. (Have a
look on the web at Project Sanguine I think its called) If a really
long wire is laid out at low elevation - just lying on the ground even -
then fed against a real earth connection then a ground loop will be set
up. There will probably not even be a need to ground the far
end. With a skin depth, particularly in low conductivity
ground, measured in 10s or 100s of metres then quite a large loop will
result.
I
know ground loops were tried on 73kHz, with only moderate sucess, but the
much lower frequency ought to improve the efficacy of the system.
Even in my urban plot, it will be possible to lay out several hundred metres of
wire by just trailing it over the garden wall and along a grass verge by
the road. I'll be limited in wire length only by roundabouts where
the verge stops.
Andy G4JNT
The corrected figures are even more dramatic than for the
loop.
To feed 1kW into the 180m high 15mm copper pipe the current
must be 154A and the voltage on the antenne becomes 2.5MV! Perhaps the
pipe would survive the current but the voltage makes the system completely
unrealistic (corona).
And what would the required 286mH loading coil for that
voltage and current look like
...
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