Design and characterization of elevated CPW and thin film microstrip structures for millimeter-wave applications

A new family of low loss series/shunt matching stub structures, based on a CPW/thin film microstrip combination using an MMIC airbridge approach to realize an elevated transmission line, is presented. This airbridge approach to elevate the CPW centre conductor and thin-film microstrip line was developed to achieve low losses in the millimeter-wave frequency band with a wide impedance range. By elevating lines from the substrate, the dielectric loss can be reduced. We achieve high impedance with a lower attenuation level than conventional CPW and low impedance with an air-substrate thin-film microstrip. Experimental results are presented in support of the novel structures.