A method for analyzing waves in structures consisting of metal strips on dispersive media

A method for analysis of wave propagation on structures consisting of periodic metal strips is presented. The method is an extension of earlier theories based on Legendre polynomial expansions of the electric field. The extension allows analysis of strips on any material or layers of materials, provided the electromagnetic properties can be expressed in terms of a wavenumber-dependent permittivity. Layers of dielectrics, piezoelectrics, semiconductors, and metals are typical of the materials of practical interest in connection with surface wave acoustics. Strip configurations such as interdigital transducers, multistrip directional couplers and reflectors, and strip coupled amplifiers can be analyzed by the present approach. Prescriptions for calculating the amplitudes of the space harmonics of the electric field strength are given. Closed-form expressions for strip current and voltage are developed.