A Multi-Solver Scheme Based on Combined Field Integral Equations for Electromagnetic Modeling of Highly Complex Objects

A combined field integral equation (CFIE)-based multisolver scheme is presented for electromagnetic modeling of objects with complex structures and materials. In this scheme, an object is decomposed into multiple bodies based on its material property and geometry. To model bodies with complicated materials, the finite element-boundary integral (FE-BI) method is applied. To model bodies with homogeneous or conducting materials, the method of moments is employed. Specifically, three solvers are integrated in this multi-solver scheme: the FE-BI(CFIE) for inhomogeneous objects, the CFIE for dielectric objects, and the CFIE for conducting objects. A mixed testing scheme that utilizes both the Rao-Wilton-Glisson and the Buffa-Christiansen functions is adopted to obtain a good accuracy. In the iterative solution of the combined system, the multilevel fast multipole algorithm is applied to accelerate computation and reduce memory costs, and a preconditioner based on an absorbing boundary condition is employed to speed up the convergence. In the numerical examples, the individual solvers are first demonstrated to be well conditioned and highly accurate. Then, the validity of the proposed multisolver scheme is demonstrated and its capability is shown by solving scattering problems of electrically large missilelike objects.