In this paper the authors apply the Method of Moments (MoM) to the analysis of the scattering of a multilayered periodic strip grating by a plane wave with oblique incidence and arbitrary polarization. The problem is initially solved by means of the MoM in the spectral domain. However, since this approach leads to the computation of slowly convergent series, the problem is also solved by using a mixed potential integral equation (MPIE) formulation of the MoM in the spatial domain. Thanks to the efficient computation of the periodic potentials Green?s functions and thanks to the closed-form integration of part of the integrals involved in the MoM matrix entries, important CPU time savings are attained when applying the MoM in the spatial domain. In fact, the implemented spatial domain version of the MoM turns out to be one order of magnitude faster than the spectral domain version when basis functions that account for edge singularities are used in the modeling of the current density on the metallizations
