Characteristic impedance of integrated substrate gap waveguide

Abstract

A theoretical method is presented by which characteristic impedance of integrated substrate gap waveguide (ISGW) is analyzed. The method is essentially based on a variational function for the transmission-line capacitance in Fourier-transformed domain with test/trial functions of charge density distribution, in which transverse transmission-line Green's function is used to facilitate the variational analysis. The presented method simplifies the determination of the potential distribution function which must satisfy the complex boundary conditions of the ISGW. Moreover, two types of ISGW, that is, twoand three-layer ISGW, working in K and E band are considered and analyzed by this method. Finally, the method is compared to the simulated using High Frequency Structure Simulator (HFSS) as well as measurements, and it is shown that the method leads to a very small inaccuracy compared to previously reported methods.