Effect of substrate dielectric inhomogeneity in the dispersion characteristics of a microstrip line

Abstract

In this article, we apply the spectral domain method of moments to calculate the dispersion characteristics of a microstrip line, which is located on top of a grounded dielectric substrate. The dielectric substrate is a one-dimensional inhomogeneous material whose permittivity varies continuously in the direction normal to the ground plane. To make the spectral domain analysis applicable to a general inhomogeneous profile, we propose an accurate numerical algorithm to calculate the spectral domain transverse dyadic Green's function for an inhomogeneous substrate with an arbitrarily varying permittivity. The method is then used to obtain the dispersion curves for several inhomogeneous profiles and the results are compared with those of Ansoft HFSS simulator to verify the validity and accuracy of the proposed method. © 2014 Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:1819–1822, 2014