Modified Separated Potential Integral Equation for Low-Frequency EFIE Conditioning

In this work, a methodology to address the low-frequency stability issues common to electric-field integral equation (EFIE)-based 3-D full-wave electromagnetic solvers is presented. The proposed formulation uses a separated potential integral equation (SPIE) approach which appends scaled electric scalar potentials to the electric currents as unknowns. The limitations of the existing SPIE technique, particularly for lossless and low-loss geometries, are addressed by enforcing charge neutrality and a potential referencing scheme. An appropriate preconditioning strategy is implemented for fast iterative solution of the system. The method seamlessly transitions into high-frequency solutions and therefore presents a true broadband formulation. Numerical experiments demonstrate over 20x speedup in convergence at low frequencies as compared to traditional SPIE