Conductor-backed coplanar waveguide to microstrip transition on BCB polymer thin film with bandwidth over 60 GHz

A conductor-backed coplanar waveguide to microstrip via-hole less transition realized on a commercial BCB (Benzocyclobutene) polymer thin film is studied in this paper. By using thin substrates with a low-permittivity, the achieved experimental bandwidth covers the frequency band from 1 GHz to 69 GHz. This transition, using electromagnetic coupling between the bottom and top ground planes, is very useful and requested in component packaging, on-wafer measurements of microstrip based monolithic microwave integrated circuit and for interconnections in hybrid circuits including both microstrip and coplanar structures.