Topband: How to measure ground conductivity / characteristics for RF?

Kristinn Andersen kiddi at marel.is
Mon Feb 7 08:55:40 EST 2005


Hi, everyone:

I live in a terrain that I am not sure how to characterize in terms of 
ground conductivity.  The surrounding streets are paved asphalt and the 
entire area is built on an old, rugged lava field topped with a shallow 
layer of rocks, sand and mud (some might call it soil...).

I have sometimes wondered what role the ground really plays in the 
radiation characteristics from my antenna.  For example, I have had fairly 
good success with low horizontal wires on topband, while most advise 
against this as the ground is believed to "mirror" the antenna currents 
and cancel the radiation.

Is there any good way to measure or estimate the ground characteristics 
with respect to radio waves on the low bands (1.8 and 3.5 MHz)?  Primarily 
the conductivity, but also the dielectric constant (which I have never 
grasped what role plays w.r.t. the propagation from the antennas, by the 
way).  Any "radio-based approach" to measuring the ground parameters, 
rather than sticking rods into the earth and try to get any estimates that 
way.

73 de TF3KX, Kris


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