Scattering of a transient electromagnetic wave by a dielectric sphere

The transient scattered field from a lossless dielectric sphere is evaluated by the inverse Laplace transform of the frequency-domain solution. Two methods of obtaining the inverse transform are employed. In the first approach, direct numerical evaluation of the Bromwich integral is carried out. In the second approach, the asymptotically compensated singularity expansion method is employed. The numerical results obtained from both methods are in complete agreement. Reference to the physical origins of the various structures appearing in the time-domain response is made by considering the dependence of their magnitude and time of arrival on the permittivity. Verification of the various predictions previously given by frequency-domain analysis can be carried out in a different perspective with new physical insight.