Improving the accuracy of the Calderón preconditioned CFIE by using a mixed discretization

The scattering of time-harmonic electromagnetic waves by perfect electrically conducting (PEC) objects can be modeled by several boundary integral equations. The most prominent ones are the electric and magnetic field integral equations (EFIE and MFIE). The former is applicable to both open and closed structures, whereas the latter is applicable to only closed structures. The EFIE is susceptible to the dense grid breakdown: when the smallest edge size in the surface mesh tends to zero, the condition number of the system matrix resulting from the standard boundary element method (BEM) discretization of the EFIE tends to infinity. This renders the iterative solution of the BEM system inefficient or even impossible. This problem can be mitigated by Calderon preconditioning, i.e. exploiting the self-regularizing property of the EFIE operator.