Calderón multiplicative preconditioned EFIE with perturbation method

In this paper, we address the low-frequency breakdown and inaccuracy problems in the Calderón multiplicative preconditioned electric field integral equation (CMP-EFIE) operator, and propose the perturbation method as a remedy for three-dimensional perfect electric conductor (PEC) scatterers. The electric currents at different frequency orders as a power series can be obtained accurately in a recursive manner by solving the same matrix system with updated right hand side vectors. This method does not either require a search for the loops in the loop-tree/-star based method or include charge as additional unknown in the augmented EFIE method. Numerical examples show the far-field pattern can be accurately computed at extremely low frequencies by the proposed perturbation method.