A Full-Wave Hybrid Numerical Method for Quasi-Optical System With Multiple Complex Objects

In this letter, to improve the calculation efficiency, a novel full-wave hybrid numerical method based on the finite-difference frequency domain method (FDFD) and the surface integral equation method (SIE) is proposed for the quasi-optical (QO) system featuring multiple objects with complex structure. The objects are modeled by FDFD in separate regions, which are coupled with each other and the reflectors in the QO system by SIE are derived from Stratton–Chu formula. The use of FDFD makes the solution matrix sparse, and employing SIE enables the elimination of grids on the transmission path, both of which can improve the calculation efficiency. A quasi-optical beam splitter system is taken as an example to prove the correctness and effectiveness of our method. Compared with the commercial software FEKO using the multilevel fast multipole method, the results calculated by our method are verified, and the calculation speed can be improved several times in normal case.