Relevance of the resonances of Green's functions when solving shielded cavity-based structures with an mpie strategy

The relationship between the Green function of an empty rectangular cavity with perfectly electric conducting (PEC) walls, its resonances and the eventual modal degeneracy is described. For this purpose a classification of the cavity modes according to their degeneracy will be presented first. Afterwards these modes will be identified inside the expressions of the Green functions appearing in the Mixed Potential Integral Equation (MPIE) formulation. Later these modes will be related to waveguide modes. Finally results are presented.