SDFMM-based fast analysis of radiation and scattering from finite microstrip structures

The prediction of radiation and scattering from microwave circuits and multilayered patch antennas is essential in the design of many communication systems. The analysis of electromagnetic phenomena involving large-scale quasiplanar structures requires efficient and accurate numerical techniques. The most popular approach for analyzing scattering and radiation from such structures relies on surface integral equation formulations and method of moments (MoM) based solution techniques. The application of the MoM to solve surface integral equations leads to a matrix equation involving a dense matrix. In this work, the steepest descent fast multipole method (SDFMM) is applied to the full-wave analysis of microstrip structures on finite substrates and ground planes. The quasiplanar nature of such structure is exploited to obtain matrix vector products in O(N) CPU time and memory, resulting in a dramatic solution efficiency. Owing to the multiregion nature of the present analysis problem, not all N MoM basis functions are independent. The required identification of independent functions, N/sub ind/ in number, and enforcement of appropriate boundary conditions are incorporated through another matrix transformation. The SDFMM permits the solution of scattering and radiation from extremely large and complex structures within realistic times. These include large microstrip patch arrays with finite substrates and ground planes modeled using 90,000 or more MoM basis functions.