Transient electromagnetic wave scattering by a dissipative dielectric sphere

The scattered field from a step-excited dielectric sphere is evaluated by the numerical Bromwich integration and a recently developed asymptotically compensated singularity expansion method. Both lossless and dissipative cases are considered. Excellent agreement is observed between the numerical results obtained using the two techniques. An interpretation of the various features in the return signal in terms of their physical origin is presented. It is concluded that spectral summation methods provide an effective means for the treatment of dissipation and dispersion phenomena which are encountered in realistic scatterers and wave supporting media. The use of proper asymptotics or its compensation allows not only a considerable reduction in the computation time required to achieve a given accuracy but also the determination of unknown entire functions, making the recovery of the early-time response possible.<>