Full-wave Analysis of Microstrip and Slotlines

A full-wave approach based on the use of Green’s functions of layered structures is applied to determining the wave propagation constant. An open microstrip line with a layered substrate and a slotline located inside a rectangular waveguide are under investigation. The transverse resonance technique is used to determine the propagation constant. The proposed approach allows the use of materials with arbitrary electrophysical properties. The constant propagations of both the main mode and higher-order waves can be determined. A method for accurate and approximate determination of the wave impedance of the line is described. Graphs of the dependence of the propagation constant on the dielectric constant and the thickness of the substrate are presented. A large range of variation in the propagation constant of a slit line integrated into a rectangular waveguide is noted when its width varies. The results obtained are useful for designing transitions between microstrip, slit and waveguide transmission lines.