In this paper, we develop a method for the analytical evaluation of the inverse Laplace transform representations for a transient transverse magnetic (TM) plane wave obliquely incident on a conductive half-space. We assume that the permittivity and conductivity of the dispersive half-space are independent of frequency. The time-domain expressions for the reflected and transmitted waves are first represented as inverse Laplace transforms. The transient fields are then shown to consist of two canonical integrals. The canonical integrals, in turn, are solved analytically, thereby yielding closed-form solutions involving incomplete Lipschitz-Hankel integrals (ILHI's). The ILHI's are computed numerically using efficient convergent and asymptotic series expansions, thus enabling the efficient computation of the transient fields. The exact, closed-form expressions are verified by comparing with previously published results and with results obtained using standard numerical integration and fast Fourier transform (FFT) algorithms. An asymptotic series representation for the ILHI's is also employed to obtain a relatively simple latetime approximation for the transient fields. This approximate late-time expression is shown to accurately model the fields over a large portion of its time history.
ASJC Scopus subject areas
- Electrical and Electronic Engineering