Measurement and modeling of soil electromagnetic behavior

The paper presents procedures to measure and model soil electromagnetic parameters, as a function of frequency, adequate for frequency domain and transient studies of soil behavior and its effect in grounding. Such procedures take into account the problems related to field measurements, the need of a physical validation, and the great diversity of soil characteristics. The physical model, with a small number of numeric parameters, reproduces, within measurement accuracy and small heterogeneity effects, the measurement results, assuring consistent physical behavior. The authors present the results obtained, using such procedures, of a large number of soil samples, with very different structures and geological origins, and quite far apart, and a statistical analysis of such results. Some examples illustrate the effect of soil parameters, namely in the frequency domain and for impulses typical of lightning discharges.