A combined finite element-boundary element formulation for solution of two-dimensional problems via cgfft

A method for the computation of electromagnetic scattering from arbitrary two-dimensional bodies is presented. The method involves a combination of the finite element and boundary element methods with particular emphasis on forms of the boundary integral aimed at reducing the storage requirement. Two types of boundary enclosures are investigated, both leading to convolutional boundary integrals which may be evaluated via the FFT in conjunction with the CG algorithm to reduce the storage requirement. Specifically, the circular and ogival enclosures are considered. Of these, the first leads to completely convolutional integrals, whereas the ogival contour yields partially convolutional integrals and the remaining must be efficiently evaluated to maintain the O(N) memory requirement. Results for several circular and ogival structures are presented and shown to be in excellent agreement with those obtained by traditional methods.