Re: Test results

	You've perked my interest,
>The distance between our transmit and receive antenna array is 1.5 miles.
>By using an array of copper ground rods spaced 1000 ft. from another, we
>were able to obtain a dc resistance of 50 ohms between the two.
>Then we injected a 7hz sine wave into the earth at various signal levels.
That looks like a great ground substrate.  Just for grins, I measured
my ground: 2 8' rods ~45' apart: 10 ohms, but my brackish water table
is only 12' down. Do you know what level your water table is? 

>At the receive site, (1.5 mi distant) we recovered the transmitted signal
>after using standard low pass filters. After amplification the signal
>was recorded and analyzed.
What was the gain? You recorded 2.5 or 5 volts in the spectrum
analyser, divide by the gain to get the picked up signal level.
>All input signals were transmitted from the signal source at 7 hz into
>a 50 ohm resistance.
Was this the 50 ohms of your ground array or an additional 50 ohms
series resistance? Did you drive the ground rods in a balanced or
unbalanced configuration? 

Have you considered running a sweep, with your signal generator, to
see what the earth's transfer curve is?

It took me awhile to find the marks in the gifs: T-0 came through as
img-gif0, T-1 as img-gifb, T-2 as img-gifc, 5V spectrum as img-gifa,
and the 2.5V spectrum as img-gifd.

Those were some well done screen captures of your spectrum analyser
output. What program/hardware did you use for the spectrum analyser?