Oblique scattering from lossy periodic surfaces with applications to anechoic chamber absorbers

Plane wave scattering from lossy, periodic surfaces with periodicity in one direction is considered for arbitrary polarization and incidence angles. The material is assumed to be homogeneous and characterized by complex values of permittivity and permeability. Muller-type coupled integral equations are derived for the surface electric and magnetic currents. The power reflection coefficient is defined in terms of the scattered far fields. The integral equations are solved by the boundary element method (BEM) with constant elements. Arbitrary surfaces are accommodated by approximating the actual profile by means of linear segments. Other speed-up techniques are utilized to generate a numerically efficient solution. Substantial comparison is made for special cases to verify the formulation. The reflection coefficient is calculated for a variety of surface shapes. A new profile shape is presented that results in a lower reflection coefficient than the commonly used triangular shape