Effect of Dispersive Soil on the Electromagnetic Response of Buried Wires in the UHF Range

In this paper, we analyze the effect of the soil on the induced current in a buried wire excited by an external field in the ultrahigh frequency range. We use an extended version of the Messier model, which provides the electromagnetic (EM) properties of dispersive soils. Based on comparisons of the Messier model and experimental data, it is verified that this model can be used up to a frequency of about 4 GHz for wet soils. A buried straight wire is used for analyzing the soil effect on the EM coupling with an external plane wave impinging from the air. It is shown that the effects of the soil on the EM response of a wire are mainly (i) to modify its electrical length and (ii) to attenuate the incident wave and, as a consequence, the induced current in the wire. The accuracy of the path decomposition method is assessed. It is shown that this method can be used to estimate with reasonable accuracy the behavior of the induced current. Finally, we study the influence of the frequency‐dependence of the soil parameters on the EM coupling to a buried wire. We show that the dispersive nature of the soils affects the spectral content of induced currents in buried wires. Therefore, it can be concluded that the frequency dependence of the soil parameters should not be neglected in EM coupling calculations in the UHF range, especially for low resistivity soils (ρ < 300 Ωm, corresponding to wet soils).