Broadband transition between double-sided parallel-strip line and coplanar waveguide

A broadband transition between double-sided parallel-strip line and coplanar waveguide is proposed in this letter. This design is based on tapered structure and vertical coupling, which doesn't require any via hole. The proposed transition has a simple structure for easy fabrication. Several parameters are studied by simulation to optimize the transition. A demonstration back-to-back transition is fabricated and measured. The experimental results show that the insertion loss of less than 1.4 dB and the return loss of better than -10 dB is obtained from 1.3 to 9 GHz. © 2007 IEEE.