A broadband transition between microstrip and coplanar stripline

A design for a broadband microstrip-to-coplanar-stripline transition using broadside-coupled strips is proposed in this letter. Two transitions are designed in back-to-back configuration and the insertion loss is optimized in X-band (8.2 GHz/spl sim/12.4 GHz). Both simulation and measurement are in good agreement. The measured bandwidth for 1 dB insertion loss and 20 dB return loss is from 6.9 GHz to 12.4 GHz.