An Investigation of Hybrid Techniques for Scattering Problems on Disjunct Geometries

We have investigated two kinds of hybrid methods for the electromagnetic scattering problem in the mid-frequency range. These are, a current-based approximation to the Magnetic Field Integral Equation called Physical Optics (PO) and the ray-based method Geometrical Theory of Diiraction (GTD), both combined with the Method of Moments (MM) such that MM is used on details that are small compared to the wavelength, and the approximation is used on details which are large in that sense. The methods have been tested on geometries that reveal both the beneets and drawbacks of the approximations used. The MM/PO hybrid iteratively corrects the currents by multiple reeections. The results show that the MM/PO hybrid produces Radar Cross Sections (RCS) whose shapes are close to the true MM solution. The MM/PO hybrid is signiicantly faster than the MM solver. The MM/GTD hybrid is tested on a RCS test case. The hybrid modiies the incoming eld to the MM-geometry by using GTD 2]. Also the scattered eld is modiied with GTD-terms. The test cases show that the hybrid is an eecient and accurate method if the two geometries, represented by two methods, are separated by more than a few wavelengths.