Electromagnetic wave scattering by an infinite plane metallic grating in case of oblique incidence and arbitrary polarization

A novel spectral-domain method combined with a sampling theorem is applied to the rigorous analysis of this quasi-two-dimensional problem. The accuracy and convergence of the method are examined numerically taking into account errors in comparison with extrapolated values, errors in the power relation, and the duality relationship. It is found that the numerical results exhibit good convergence. Another formulation related to Babinet´s principle is discussed, and a relationship between the fields of an original and its complementary gratings is demonstrated. Numerical calculations are carried out showing that the method provides precise numerical results not only for the far fields, such as transmitted and reflected powers, but also for the near fields, such as surface current distribution on a strip and electric field intensity in a slit. Some numerical results related to the dual problem are provided