Evaluation of the frequency-dependent ground wave loss technique for measuring effective ground conductivity and permittivity at HF

The frequency-dependent HF ground wave loss technique for measuring the effective conductivity and relative dielectric constant of the ground has been validated by carrying out loss measurements for a single path over fresh-water and for 12 paths over solid earth. Results are compared with data obtained from other techniques, such as 4-probe resistivity, 2-loop induction and laboratory sample analysis techniques. Even after due allowance has been made for the differing soil penetration depths of the various methods, we find that discrepancies by up to a factor of 3 can occur between derived values of conductivity. We conclude that if ground conductivity measurements are required for the purpose of predicting the radio frequency performance of planned HF systems, the frequency-dependent loss technique is preferred over non-HF methods because of: (a) its direct applicability to the HF band, and (b) the relative ease with which it is able to characterise ground constants over an entire site several km in extent.