A wideband differential microstrip-to-waveguide transition at W-band

A W-band inline transition between differential microstrip lines and a rectangular waveguide is presented. It is based on finlines on an ultrathin liquid crystal polymer substrate inserted in a WR10-waveguide. The designs are presented and the performance of the transitions is evaluated in simulation and measurements. The back-to-back measurement results show good agreement with simulation and exhibit less than 1.6 dB insertion loss and more than 8 dB return loss over the whole W-band.