Full-wave analysis of various coplanar bends and T-junctions with respect to different types of air-bridges

Various types of air bridges within bends and T-junctions are innvestigated using an extension of the spectral domain analysis method for analyzing three-dimensional metallization structures. Generalized scattering parameters are calculated to compare the different bridge layouts. In order to check the accuracy of the algorithm, four coplanar T-junctions on a GaAs substrate containing three standard air bridges and one modified air bridge have been built and measured. For the even mode scattering parameters, a very good agreement over the whole frequency range, compared to the calculated results, is obtained. Various data for conversion from the even mode to the odd mode within these structures are also given. As a result of the investigations, some design ideas for coplanar waveguide (CPW) circuit designers are determined. Problems in coplanar measurements using probe tips are discussed.<>