Calculation of the Harmonic Impedance of a Single Horizontal Grounding Wire in Two-Layer Soil by The Electromagnetic Model

Grounding systems behavior at high frequencies in EMC modeling studies is usually approximated by a dc resistance to ground. This is mainly due to the lack of systematic information on high frequency behavior of specific grounding electrode arrangements. In this paper grounding impedance of a horizontal wire in a two-layer model of soil is estimated from a rigorous electromagnetic field approach. The mathematical model is based on a mixed potential integral equation with exact Green's functions in the layered medium that involve Sommerfeld type integrals. Computational model based on the method of moments yields currents, fields and voltages. This full-wave model is compared to more approximate but computationally more efficient model based on image theory. Also preliminary parametric analysis is presented for horizontal grounding electrodes.