An iterative MPIE formulation for the RCS computation of microstrip patches

The use of FFT (fast Fourier transform) algorithms for the computation of resonant frequencies of microstrip patches is examined. Ordinarily, such a scheme alone may not be adequate for a precise solution. However, a judicious combination of the mixed potential integral equation (MPIE) formulation and iterative methods at the vector-level provides acceptable answers for particular geometries and for certain far-field quantities of interest. In the example chosen, a rectangular patch was discretized into 14*10 square cells and a 32*32 point FFT was used. A primary advantage of the approach is its simplicity and the very flexible upper limit on the number of the cells that can be handled, arising from the absence of the moment-method matrix. This allows a very convenient treatment of finite ground planes and also of coupled patches of odd geometries. The disadvantages are those inherent in all FFT-based and iterative methods.<>