HIGH-FREQUENCY ANALYSIS OF ELECTROMAGNETIC SCATTERING DUE TO A DIELECTRIC CYLINDER

As a canonical problem to understand the electromagnetic scattering by a dielectric body, the scattering characteristics of the plane wave by an infinitely long dielectric cylinder is analyzed by a high-frequency approximation. The rigorous solution of the scattered electromagnetic field by a circular cylinder is separated into the component scattered by the cylinder surface and the one transmitted into the interior of the cylinder by means of Watson transformation and Debye expansion. By applying appropriate high-frequency approximations to each component, geometrical optics representations for reflection, transmission, and diffraction are provided. Especially for the diffracted field, an approximate solution more accurate than the conventional approximate solution is obtained. By UTD extended to a dielectric cylinder problem, an approximate solution in the transition region is derived which has not been derived by the conventional high-frequency approximation. To investigate the validity of these approximate methods, the results of the analysis by the present method are compared numerically with the rigorous solutions in the frequency domain and the time domain. It is proven that the present high-frequency approximation method is extremely accurate except near the critical scattering angle.