Scattering at open perfectly electrically conducting objects using calderón preconditioning and fast multipole methods

Calderón preconditioning is very succesful in stabilising the EFIE and the use of BC functions makes the formalism valid on open surfaces. Through applying a broadband fast multipole method, the complexity can be reduced from O (N
²
) to O(N log N), allowing the simulation of very large structures. In the high frequency case a localised version of the preconditioner must be used to avoid excessive scattering of the eigenvalues of the combined operator.