Improve the accuracy of the second-kind integral equations for generally shaped objects

Second-kind integral equations (IEs) are used to be considered as less accurate than their first-kind counterparts. Previously, it has been shown that by using the Buffa-Christiansen (BC) functions as the testing function, the numerical accuracy of the second-kind IEs in the far field calculation for spherical objects can be improved significantly. In this paper, this technique is generalized to be applicable for generally shaped objects for both the perfect electric conductor (PEC) and the dielectric cases by using the BC functions as the testing function, and handling the near-singularities in the evaluation of the system matrix elements carefully. Several examples are given to demonstrate the performance of this technique.