Padé approximation for time-domain plane wave reflected from a lossy earth

Abstract

To deal with the behaviour of wire structures subjected to electromagnetic waves with the finitedifference time-domain (FDTD) method, it is necessary to establish the external electromagnetic excitation in time-domain. For a homogeneous lossy half-space problem, the Fresnel reflection coefficients for arbitrary polarization plane wave are usually multiplied by the pulse spectrum in the frequency domain and the result is transformed into the time-domain. In this paper, an accurate method based on the Padé approximation theory in conjunction with the partial fraction expansion is used, and leads to expressions of the field above a homogeneous lossy earth that can analytically be transformed into the time-domain. The influence of the common degree of the numerator and denominator of the Padé approximant on the accuracy of the proposed method is discussed.

Time-Domain Analysis for the Coupling Problem of Overhead Lines Above Multilayered Earth

“…In order to study the plane wave coupling to overhead lines over stratified soil, the primary field composed of the incident electric field e i (t) and the field e r (t) reflected from the soil [18] is needed to obtain explicit expressions of the distributed voltage and current sources along the line. The general expression of the primary field in the time domain E(t) above the stratified medium is…”

“…Given the nature of the waveform, i.e., a biexponential, the convolution product γ Υ e 0 (t) appearing in expressions ( 14) and ( 15) is accurately calculated using the recursive convolution introduced in [18].…”