Electromagnetic Scattering from a Non-Planar Periodic Conducting Grating, and its Equivalent Surface Impedance

Abstract

A semi-analytical method for plane wave scattering by a two-dimensional (2D) non-planar, comb-like metallic grating with a one-dimensional periodicity is presented for both the transverse magnetic (TM) and transverse electric (TE) incident wave cases. The problem is reduced to a Cauchy-type singular integral equation for the magnetic (TM) and electric (TE) current jump across the vertical conducting strips. The singular integral equation is solved accurately using what is essentially a spectral domain moment method technique with Chebyshev polynomials as expansion and weighting functions. As an application, the equivalent impedance of the grating structure is calculated for situations where only the specularly reflected wave exists far from the structure. The condition under which the equivalent impedance becomes independent of the incidence angle is also addressed.