Solution to 3-D electromagnetic problems discretized by a hybrid FEM/MOM method

A hybrid finite-element method/method of moments (FEM/MOM) is used to solve 3-D electromagnetic problems. We are focused on the solution to the resulting system of linear equations. Because of the hybrid nature of the FEM/MOM method, the coefficient matrix of the linear system has a very special structure with sparse but indefinite sub-matrices generated by the FEM and dense sub-matrices generated by the MOM. Preconditioned Krylov subspace methods are employed to solve the linear systems. Three preconditioners are considered and analyzed regarding the special structure of the coefficient matrix. Numerical results obtained from scattering and radiation problems show that the BICGSTAB method accelerated by a preconditioner, which employs several GMRES iterations to approximate the Schur complement, is reliable and efficient for the solution of the linear system.