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 saw-tooth profile can he used to reduce the backscattering at high frequencies and elliptical profiles san be used to reduce the backscattering at certain low frequencies when a cover material is filled in the grooves
