Time-domain asymptotic solutions in the transition regions near geometrical boundaries and near caustics for scattering by a dielectric cylinder

Studies on the scattering of electromagnetic fields by a dielectric cylinder have been an important research subject for a variety of applications in the area of antennas and propagation. In this study, a time-domain asymptotic analysis is discussed for the scattered electromagnetic fields when the cylindrical wave radiated from a magnetic line source is incident on a dielectric cylinder. We assume the Gaussian-type modulated pulse source whose spectrum is distributed in the high-frequency domain. The time-domain scattered field solutions derived in this paper are applicable in the transition regions near the geometrical boundaries, produced by the incident ray on the dielectric cylinder from the tangential direction, and near the caustics, produced by the family of the reflected ray group on the concave side of the dielectric cylinder. Comparisons of the time-domain asymptotic solution with the reference solution calculated numerically from a combination of the eigenfunction representation and the First Fourier Transform (FFT) code confirm the validity and the utility of the proposed time-domain asymptotic solution.