Dielectric and conductor losses in coplanar waveguides

Abstract

AbstractConductor and dielectric losses in a coplanar waveguide are analyzed and the results are verified experimentally. Since the waveguide is made of two conductors, TEM transmission is assumed and the Laplace equation for the potential distribution in the waveguide cross section is solved. From the resultant potential distributions, the current distributions on the conductor surfaces and the conductor loss are obtained. We also obtain the effective dielectric constant, which expresses the electrical effect exerted on the waveguide by the dielectric substrate. From this quantity, the dielectric loss is derived. The Laplace equation is solved numerically on a computer using the successive overrelaxation method. Only one quarter of the cross section is analyzed due to symmetry, so that computation time and memory requirements are reduced. The experiment verification of these results involves measurement of Q of a resonator consisting of a coplanar waveguide. The difference between the theoretical and experimental values is less than 25% for the conductor loss and less than 6% for the dielectric loss.