Having just moved to ZL recently, I decided to measure the soil conductivity
with a view to getting an idea of what kind of radiation characteristics I
can expect from a 160m vertical. (I hope to be able to economise on the
radials as well)
I used the ARRL Antenna Book method, but noticed on the diagram that the
cold side of the AC supply is grounded. Surely that affects the results
quite seriously, or am I missing something?
When I performed the test as per the book, I found that it made no
difference at all to the results whether the fourth electrode (neutral) is
connected or not. The AC supply neutral is obviously connected to ground
somewhere else. I therefore decided to modify the setup and use an
isolation transformer, and things then worked out OK.
I was quite surprised at the result I obtained of 10 mS/m. This a little
higher than normal, but not as high as I had expected, as the ground is
soaking wet - must be a low concentration of minerals I suppose.
Does anyone know of a way of measuring the dielectric constant?
I would propose making an insulated parallel plate cap with a sample of soil
as the dielectric, feeding with a sniff of RF at 1.8 MHz, and doing an
impedance measurement. Has anyone done this before?
73, Greg, ZL3IX
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