Backscattered short pulse response of surface waves from dielectric spheres

A short pulse response for surface waves involved in the backscattering by dielectric spheres is considered in the time domain. Since the surface-wave contributions for the cw backscattering are known, pulse returns for the surface waves are obtained from the cw solutions by Fourier synthesis. Large savings in computation time for a Fourier series were realized with the use of the fast Fourier transform algorithm. The return positions in the short pulse response can be approximately estimated from a scattering model for surface waves depicted by Van de Hulst. With the propagation constant in the dielectric sphere rather than in free space for a wave traveling along the sphere surface, a better agreement between the predicted and calculated positions for the short pulse returns was obtained. Significant returns of surface waves for the backscattering come from the surface waves that have made the maximum number of shortcuts possible through the sphere.