A general framework for the OSRC-preconditioned EFIE in computational electromagnetics
We investigate on-surface radiation condition (OSRC) preconditioners for the electric field integral equation (EFIE), considering Electric-to-Magnetic (EtM) and Magnetic-to-Electric (MtE) approximations applied from both the left and the right. A pseudodifferential analysis establishes the well-posedness of the four resulting formulations and shows that, locally, the OSRC EtM and MtE approximations present a similar structure to the EFIE itself and its inverse, respectively. At the discrete level, both MtE formulations are compatible with the standard RWG/SNC discretization and can be implemented without barycentric refinement, whereas the EtM formulations require an appropriate discrete duality map and BC/RBC spaces. Numerical experiments show that the OSRC preconditioners substantially improve GMRES convergence compared with the unpreconditioned EFIE, with the refinement-free MtE formulations also providing the lowest computational cost among the formulations considered.