RCS computation for a large array of waveguide slots with finite wall thickness using the MoM accelerated by P-FFT algorithm

This correspondence presents an accurate and efficient method of moments (MoM) for analyzing electromagnetic scattering by a large finite array of waveguide slots with finite thickness. In this method, the mixed potential integral equation (MPIE) is utilized onto both upper and lower surfaces of the slots, and the subdomain MoM procedure is implemented to obtain the equivalent magnetic current distributions. The precorrected fast Fourier transform (P-FFT) method is employed to accelerate the entire computational process to reduce significantly the memory requirements for large arrays. During the MoM procedure, the Rao-Wilton-Glisson (RWG) functions are used as the basis and testing functions, with both z- and x-directional magnetic currents considered. This approach extends applicability of the present method to solve the MPIE for characterizing waveguide slots of arbitrary shape and distribution and the capability of the integral equation based fast algorithm. Numerical results are obtained and compared with the experimental results, to verify the accuracy and efficiency of this technique.