New Substrate-Integrated to Coplanar Waveguide Transition

A novel design for a transition from substrate-integrated waveguide (SIW) to regular coplanar waveguide (CPW) is presented. In comparison with previously published transitions, which employ conductor-backed CPWs and via holes, the new design achieves better return-loss performance. Dispersion curves highlight the related modes and the available bandwidths. The new design is optimized in an HFSS environment and is presented as a single transition and as a back-to-back version with more than 30 dB and 26 dB return loss, respectively, over a bandwidth of 19.5 GHz to 27 GHz. All design parameters are specified. A SIW-to-conductor-backed CPW and via holes is presented for comparison, showing return-loss values of only 21 dB and 14.5 dB. All presented performances include dielectric and metallic losses and are verified by comparisons between HFSS and CST Microwave Studio.