Differential global surface impedance (DGSI): a rigorous model for analyzing periodic structures

Abstract

A new and efficient differential global surface impedance (DGSI) model has been developed for the analysis of periodic structures. The proposed rigorous model makes use of the equivalence principle to relate the surface electric current and the tangential electric field on the boundary of the object made of a general medium. This approach not only enables one to limit the discretization to the surface of the object located in one unit cell of the periodic structure but also eliminates the need for equivalent surface magnetic current in applying the equivalence principle. These advantages result in a great reduction in the need for computational resources and time. The use of an efficient periodic Green’s function by employing the complex images technique combined with the proposed DGSI model has increased the numerical efficiency of the proposed method. A number of dielectric periodic structures made of an array of cylinders with circular or square cross sections have been analyzed by this method. Accuracy of the proposed method as well as its numerical efficiency have been demonstrated by comparing its results with other methods in the literature employing surface and volume integral equations.