A Simple Way of Applying the Caldern Preconditioner to a Finite-Element Boundary-Integral Method

The Calderon preconditioner effectively improves the convergence of the iterative solution of surface integral equations (SIEs). This work presents an alternative way to apply the Calderon preconditioner to a finite-element boundary-integral system, as well as a twofold iterative solver where the finite-element subsystem and boundary-integral subsystem are preconditioned separately. In this approach, the finite-element domain can utilize second-order basis functions to reduce the number of unknowns required for scatterers with large dielectric constants. Numerical experiments are provided to compare the accuracy and convergence of the proposed method with the approach based on the Poincare-Steklov (PS) operator.