Finite difference analysis of cylindrical two conductor microstrip transmission line with truncated dielectrics

The characteristics of the quasi-static TEM mode of a cylindrical microstrip transmission line are investigated using the finite difference technique. The transmission line consists of two perfectly conducting strips located between two different layers of dielectric materials, and a dielectric notch embedded in the substrate between two strips. The dielectric overlay and substrate are truncated for practical purposes. The formulation of the problem is based on the solution of Laplaceʹs equation subject to appropriate boundary conditions and the use of Taylorʹs expansion to approximate the first and second order derivatives in Laplaceʹs equation. To truncate the finite difference mesh, two artificial boundaries have been considered. The goal of this research is to study the effects of the parameters of the multi-layered cylindrical transmission line on the odd and even mode phase velocities, and to present several techniques to minimize the coupling and distortion between the two conductors.