A fast converging resonance-free global multi-trace method for scattering by partially coated composite structures

Global and local multi-trace formulations provide a flexible and efficient method for the modelling of scattering and transmission of time harmonic electromagnetic waves by composite structures. This contribution extends the domain of applicability of global multi-trace formulations to cases where penetrable domains, perfectly conducting domain, and perfectly conducting thin sheets are all part of the design. A novel and easy to implement resonance free equation to model scattering by perfect conductors is introduced. A Calderón preconditioner designed to limit the number of iterations required for the solution of the discrete system is designed and studied. The accuracy, flexibility, and efficiency of the method is demonstrated on a representative range of examples.