Gap-coupled patch-type waveguide-to-microstrip transition on single-layer dielectric substrate at V-band

A compact gap-coupled patch-type waveguide-to-microstrip transition at V-band is proposed. It uses the coplanar waveguide feed patch and the gap-coupled parasitic patch antenna radiating into the waveguide to improve the bandwidth. This type of transition has a wide bandwidth (BW=4.7%) more than a single-patch-type transition (BW=1.3%) on a single-layer alumina substrate for -15 dB return loss.