On the equivalent circuit representation of the slitted parallel-plate waveguide filled with a dielectric

An investigation of the equivalent π circuit representation for the transverse slit in the wall of a transverse electromagnetic (TEM) parallel-plate waveguide is presented. For the narrow slit, approximate analytic expressions for the equivalent circuit parameters are given in terms of the centerline representation and, for the arbitrarily width slit, the equivalent circuit parameters are considered by the method of moments in terms of both the centerline representation and edge representation, and various characteristics of the equivalent π admittance circuit representation are discussed. A critical look is taken at the validity of the previous model of th E-plane gap coupling between two rectangular microstrip patch antennas, and the improved model is considered for the narrow slit (gap) width case