Abstract:
Accurate electromagnetic ground constants are required for applications such as modelling of ground
wave propagation of radio signals and antennas above a real, imperfect earth and for use in geological
surveys and agricultural applications. A simple method to determine the ground parameters (conductivity
and relative dielectric constant) for any radio frequency is outlined here. The method has been verified over
the 2–30-MHz frequency range but should be applicable up to several GHz. First, a low cost, commercial
soil moisture meter using time domain reflectometry techniques is used to determine the soil moisture
percentage. Then previously published universal soil models implemented on a programmable calculator
or a PC are used to calculate the required constants at the frequency of interest according to the measured
moisture percentage. The results obtained by this method compare favourably with those obtained by the
input impedance of a low horizontal dipole technique. The received signal strength of a ground wave, HF
transmission also compares favourably with that predicted by GRWave using ground constants calculated
by the soil moisture technique. This method offers significant advantages in terms of simplicity, speed and
cost when compared with current techniques.
