Field Representation for the Scattering of Electromagnetic Waves by Several Obstacles

The design of complex structures such as metasurfaces requires the development of efficient numerical methods, so as to deal with possibly aperiodic structures. During an optimisation process, it is necessary to perform many computation at the same wavelength while the position and properties of the scatterers are varied. We propose here a numerical scheme that allow to pre-calculate the scattering properties of arbitrary bodies in order to enhance the efficiency of the optimisation process. The method is based on a representation of the field by means of fictitious sources decomposed on a modal basis adapted to the geometry of the scatterer.