| In this thesis a straightforward means of including independently time-varying material properties in finite-difference time-domain (FDTD) formulations is presented. The approach is systematically applied to three classes of problems, namely electromagnetic wave propagation through a medium with time-varying permittivity, electromagnetic wave propagation along a medium with time-varying permittivity, and electromagnetic wave radiation from a source on a medium with time-varying permittivity. The first-mentioned class of problem has received limited attention in the literature either analytically or numerically. The second and third classes have received virtually no attention in the literature using any approach prior to the present study. By carefully selecting examples from the above-mentioned classes of problem the correctness of the FDTD predictions for these examples has been confirmed in spite of the unavailability of precise analytical solutions (due to the inherent difficulty of finding such solutions for time-invariant problems in electromagnetics) or experimental results (due to the fact that appropriate materials are not yet extant). (Abstract shortened by UMI.). |
