Application of the impedance sheet concept to thin periodically varying dielectrics

The impedance sheet concept used to predict the transmission and reflection properties of thin dielectrics is extended to determine the transmission and reflection properties of thin periodically varying dielectrics. For plane-wave incidence, the effect of the periodic interface is to generate a higher order modal distribution on both sides of the boundary. It is shown that situations exist where the higher order modes can be strongly excited, and in fact can carry more power than the dominant transmitted mode. The frequency response of the dielectric is obtained and shown to be quite different than the homogeneous thin dielectric except at lower frequencies.