Compact stubs for micromachined coplanar waveguide

This paper presents the characteristics of compact stub configurations which are suitable for coplanar waveguide implementation. The motivation behind this work is based on recent results which demonstrate that micromachined, membrane-supported transmission lines are a high-performance medium for microwave and millimeter-wave circuit design. Since the effective permittivity of the substrate is very close to 1, however, circuit dimensions can become relatively large, particularly at the low mm-wave frequencies. It is therefore desirable to reduce the component size, and a technique for accomplishing this with CPW-type series tuning stubs is described herein.