On Thu, 27 Mar 1997 22:31:46 EST firstname.lastname@example.org (T. A. Russell) writes:
>Does anyone know the conductivity of concrete?
>Is it sufficiently low to use a concrete base as a base insulator
>for a quarter wave vertical fed against ground based radials?
Perhaps someone with an antenna analyzer and a free-standing
tower could temporarily detach their ground wire from the
tower and measure the impedance between the ground wire and
the tower. Just sweep the analyzer through it's frequency
range and note the highest impedance reading. At that frequency,
the tower will be a very high impedance antenna, and the
measured impedance will represent only the leakage resistance
between the tower and ground rod. Some of the resistance would
have to be apportioned to the ground rod.
During this measurement, one would have to be careful of any
sneak circuits bypassing the tower base, such as coax lines
and grounded guy wires. My tower has grounded guys, so I can't
do the measurement on my setup.
Dave Hachadorian, K6LL
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