A study of the augmented EFIE with a Calderón preconditioner

The electric-field integral equation (EFIE) is widely used for analyzing electromagnetic scattering and radiation problems because of its excellent accuracy. However, the poor spectrum property of the EFIE operator results in a very slow convergence rate in an iterative solution. Calderon preconditioner is used to improve the spectrum property of the EFIE operator, leading to a fast convergent equation which can converge independently with respect to the mesh density of the discretization. Unfortunately, the application of the Calderon preconditioned EFIE to electrically large problems is seriously limited due to the internal resonance problem that the EFIE suffers. In order to avoid the internal resonance corruption, the magnetic-field integral equation (MFIE) is added to the Calderon preconditioned EFIE to obtain a Calderon preconditioned combined-field integral equation (CFIE). Although the internal resonance can be avoided, the accuracy of the solution is compromised because of the introduction of the MFIE. In this paper, the augmented EFIE (AEFIE) is adopted to remove the internal resonance corruption while preserving the pure electric-field characteristics and hence the accuracy, and then preconditioned with the Calderon preconditioner to improve its convergence. Several numerical examples show that the Calderon preconditioned AEFIE can indeed eliminate the internal resonance effectively and converge fast.