Rigorous analysis of scattering from a strip grating twist reflector

Abstract

Periodic metallic grating structures, with periods of the order of the wavelength of the incident electromagnetic field, influence both the phase and polarization of the reflected field. A convenient decomposition of the polarization is into fast and slow polarized modes, where the magnetic or electric field component parallel to the grating direction, respectively, is zero. In the case of a corrugated surface twist reflector, Kok and Gallagher,1 derived the optimum height required for various angles of incidence in order for the reflected fast and slow polarized modes to be in phase. In practice twist reflectors are also constructed by placing wires or strip gratings on a dielectric slab of some thickness w, backed by a conducting ground plane. Recently we presented a rigorous analysis of scattering from a strip grating. We extend our solution procedure to be applicable to the analysis of scattering from a strip grating twist reflector. It is shown that completely erroneous results are obtained if an approximate procedure is used. We compare the operation of the strip grating twist reflector to the corrugated surface twist reflector and show that the two behave similarly if air is used as the dielectric for the strip grating twist reflectors.