Ultra-Wideband CPW-to-Substrate Integrated Waveguide Transition Using an Elevated-CPW Section

In this letter, an elevated-coplanar waveguide (ECPW) is proposed for an intermediate section of a coplanar waveguide (CPW)-to-substrate integrated waveguide (SIW) transition. The ECPW is used to attain a gradual mode matching and to achieve the consequent wide bandwidth. The measurement results show 70% fractional bandwidth at 10 dB return loss and 0.9 dB insertion loss from 19 to 40 GHz. We expect that the proposed SIW transition plays an important role for the integration of high-Q SIW with CPW circuits, such as millimeter-wave system-in-package (SiP) using SIW circuits.