Dispersion behavior of the apparent permittivity for Quasi-TEM transmission lines up to 110 GHz

This paper elaborates the dispersion behavior of the apparent permittivity for microstrip lines and conductor-backed coplanar waveguides up to 110 GHz. For both transmission modes, measurements of different transmission line lengths were carried out to reduce the impact of manufacturing tolerances on the evaluated apparent permittivity. The dispersion behavior is discussed and explained by measurements and simulated electric field patterns. The field simulations for an in detail discussion of surface trapped plane waves, as well as the extended frequency range of the measurements up to 110 GHz present unprecedented results within this research area.