Electromagnetic Scattering by Surface of Arbitrary Shape.

Abstract : The electric field integral equation (EFIE) is used with the moment to develop a simple and efficient numerical procedure for treating problems of scattering by arbitrarily-shaped objects. The objects are modeled for numerical purposes by planar triangular surface patch models. Because the EFIE formulation is used, the procedure is applicable to both open and closed bodies. Crucial to the formulation is development of a set of special subdomain basis functions defined on pairs of adjacent triangular patches. The basis functions yield a current representation which is free of line or point charges at subdomain boundaries. A second approach using the magnetic field integral equation (MFIE) and employing the same basis functions is also developed. Although the MFIE applies only to closed bodies, the moment matrix of the MFIE is also needed in dielectric scattering problems and in the so-called combined field integral equation used to eliminate difficulties with internal resonances present in the MFIE and EFIE formulations. The EFIE approach is applied to the scattering problems of plane wave illumination of a flat square plate, a bent square plate, a circular disk, and a sphere. Comparisons of surface current densities are made with previous computations or exact formulations and good agreement is obtained in each case. The MFIE approach is also applied to the sphere and reasonable agreement with exact calculations is obtained.