Millimeter wave contactless microstrip-gap waveguide transition suitable for integration of RF MMIC with gap waveguide array antenna

A new simple transition from a microstrip to gap waveguides has been proposed in this paper. The transition has been implemented for ridge gap waveguide and a groove gap waveguide. The cavity coupling is used to couple the waves between the microstrip and the gap waveguides. This cavity acts as a backshort in the transition region and the microstrip lies inside the waveguide, which provides a solution to integration of RF MMIC circuits with the feed-network of the gap waveguide array antenna. Roger 3010 (εr = 10.2) was used as the microstrip substrate for these transitions. The optimised back-to-back Ridge Gap Waveguide (RGW)-microstrip transition shows relative bandwidth of 21% for S11 < −20 dB and Groove Gap Waveguide (GGW)-microstrip transition shows relative bandwidth of 20% for S11 < −17 dB. The insertion losses are better than 0.5 dB in the designed frequency bands for both the RGW and GGW transitions.