An impedance formulation to determine specular reflection from metamaterial absorbers composed of capacitively loaded strip inclusions

An impedance approach to describe specular reflection of plane waves with general direction of incidence and polarization from metamaterial absorbers composed of a metasurface of sub-wavelength sized capacitively loaded strip inclusions on a grounded dielectric substrate is studied. The possibility to model the absorber as an impedance boundary with an effective surface impedance is examined and a simple method to determine the specular reflection coefficient at oblique incidence from the normal incidence reflection coefficient is proposed.