Backscattering of TE waves by periodical surface with dielectric cover

Several types of periodical surfaces are studied on their backscattering to a normally incident TE plane wave. The surfaces are perfect conductor and are covered with dielectric materials to make a flat surface due to aerodynamic consideration. The effects of frequency, surface profile shape, period-to-depth ratio, and cover permittivity are analyzed. It is observed that a sawtooth profile can be used to reduce the backscattering at high frequencies and elliptical profiles can be used to reduce the backscattering at certain low frequencies when a cover material is filled in the grooves.