Improving the MFIE´s accuracy by using a mixed discretization

The scattering of time-harmonic electromagnetic waves by perfect electrical conductors (PECs) can be modelled by several boundary integral equations, the magnetic and electric field integral equations (MFIE and EFIE) being the most prominent ones. These equations can be discretized by expanding current distributions in terms of Rao-Wilton-Glisson (RWG) functions defined on a triangular mesh approximating the scatterer´s surface and by testing the equations using the same RWG functions. The main advantage of the MFIE is that it is well-posed in the easy-to-understand L2-norm. Discretization of the MFIE leads to systems that can be solved efficiently using iterative solution techniques. In this contribution, the cause for the MFIE´s inaccuracy is discussed, and a new discretization scheme is proposed. Numerical results are presented that demonstrate the improvement realized by the new scheme over the classical one.