A modified geometrical optics method for scattering by dielectric bodies

Abstract

A method based on ray optics is developed for calculating the scattering from dielectric bodies. The fields of geometrical optics are used except for two types of rays where the fields must be corrected from physical optics solutions. The customary advantages of ray techniques are realized, namely, a simplicity in the resulting formulas, a ready interpretation of the scattering mechanism and the possibility of extension to a wider class of problems through the inclusion of additional rays. The method has been applied to several lossless dielectric shapes: the circular cylinder, the sphere, the prolate spheroid and to a lossy dielectric shell. The relative dielectric constants considered range from 0.25 to 1.80, except in the case of the shell. The calculated results are compared with those obtained from boundary value solutions, with the exception of the spheroid where measured values are used. Good results are obtained for all sizes considered except those which are very small and behave as Rayleigh scatterers. The failure in the region of Rayleigh scattering is to be expected. Thus, for the class of dielectric scatterers treated here there is no region of scattering resonance corresponding to that of similar metallic shapes where the geometrical optics solution is no longer valid.