Broadband transition between rectangular waveguide and substrate integrated waveguide

A novel broadband waveguide-to-substrate integrated waveguide transition is presented. The transition is realised by using a fin line probe inserted into a rectangular metal waveguide. A single back-to-back transition covering the KA band is designed, fabricated and tested. Measured results show that good agreement with simulation, an insertion loss less than 1.4 dB and a return loss better than 15 dB at 25–40 GHz are obtained for a back-to-back structure. This broadband transition between the rectangular waveguide and substrate integrated waveguide can be used widely in microwave and millimetre-wave circuits and systems.