Ultra-wideband (from DC to 110GHz) CPW to CPS transition

A new ultra-wideband, low-loss and small-size coplanar waveguide (CPW) to coplanar strip (CPS) transition which can be used from DC to 110 GHz is presented. The proposed transition connects CPW wiht CPS by the reformed air-bridge. Two ground planes of VPQ are tied at their ends by a line and the centre of the line is connected to the ground strip of CPS by another line. Owing to the symmetry of the proposed structure, the currents of two ground planes of VPQ are combined with the same phase and reansferred to the ground strip of CPS. With height of 3mum, the signal line of CPW passed over two connecting lines and is connected to the signal strip of CPS. For the back-to-back transition structure, insertion loss <1 dB and return loss > 15 dB are obtained from 0.5 to 110 GHz.