A well-posed combined field integral equation for scattering from perfect electrically conducting objects

This work presents a novel regularization of the combined field integral equations (CFIE) which is immune from ill- conditioning due to dense spatial discretizations and free from internal resonances. Unlike previous approaches for preconditioning the CFIE, here regularization is achieved via analytical inversion of the hypersingular part of the CFIE followed by a summation over the Helmholtz components, this without negative repercussions on computational complexity or need for further localizations. Numerical results are presented that show the effectiveness of the proposed formulation. This paper presents the proposed regularizer in 2D because this permits a natural/intuitive and simple presentation of the underlying ideas, but the proposed preconditioner allows for a direct extension to 3D, however.