Topband: Ground parameter measurements

[Doug Waller]

>Sounds good at first glance, but how do we determine the dipole's height?
>I.e., Where is the "ground" -- at its surface? Five feet below its
>surface???  I would venture to say that as its conductivity improves, the
>closer to the surface it is. 73, de Earl, K6SE

Good point Earl.  Any ground other than a metal plate is going to have varying levels of absorbtion loss and delay.  160m RF has been detected as deep as 40+ feet below ground surface.

As it would be difficult to place probes at various depths below the surface for taking measurements, I would suggest driving a short vertical dipole at a specific low power, and taking field strength measurements a couple wavelengths out.  The weaker the field strength, the more ground loss present.  Of course, other above-ground RF absorbers and reflectors would have to be taken into account, as well as existing radials.  Standards of measurement could be developed.  This may be similar to Broadcast procedures already in use.

After having dug several holes around this 1/3 acre lot, I can say that I have found sand, black loam, red clay, wet soil and ocean bottom, in completely different percentages of makeup and depths, at each location.  If this is the norm, ground loss will have to be taken as an average number for an omnidirectional antenna.

73, om Doug / NX4D