Via-hole less broadband conductor-backed coplanar waveguide to coupled microstrip transition

Abstract

A broadband via-hole less transition from a conductor-backed coplanar waveguide (CBCPW) to a parallel coupled microstrip line (CMS) via microstrip section (MS) is reported in this paper that is realized on a MCL FX-2 substrate (100 µm thick). This transition should find a wide variety of applications due to its demonstrated broadband (from 4.5 GHz up to 39.5 GHz) behavior, ease of fabrication, and low manufacturing cost. In addition, utilization of the MS section between the CBCPW and CMS sections allows putting ground electrode in a different plane than the signal electrodes. This flexibility made possible by electromagnetic field coupling between the bottom and top ground planes simplifies the transition manufacturing and facilitates the characterization of optical components driven with CMS line using coplanar probes.