Modal Analysis of a Parallel-Plate Waveguide Containing an Internal Perforated Sheet

This article considers a structure consisting of a planar metal sheet with periodic square perforations lying between two metal plates. Generalized sheet transition conditions (GSTCs) are used to model the perforated sheet, and standard representations of the fields in the two regions of the structure lead to expressions for determining the propagation constants of the guided waves. Waveguide modes of surface wave type are found to exist on this structure, and their propagation constants are calculated. Agreement between the results of the analytical approach and the finite-element simulations is shown for various values of the perforated screen parameters, showing the analytical method to be both accurate and efficient for design.