Top-Layer Wideband Transition from Waveguide to Planar Differential Line for 60 GHz Applications

The paper describes a waveguide to planar differential line transition realized on Rogers RO4350B substrate and operating in the V band. The transition is based on a differentially-fed patch radiating element that excites a rectangular waveguide through a compact U-shaped metal adapter. The response of a single transition has been extracted from the measurement results of the fabricated back-to-back structure using a TRL calibration standard realized on the same substrate. It also allowed to accurately calibrate the differential line loss. The transition provides maximum 0.8 dB insertion loss and more than 15 dB return loss over the 57-64 GHz frequency band, whereas differential line loss of 1.3 dB per centimeter is mainly determined by the chosen substrate material. High performance and cost-effective design makes the proposed transition highly promising for different mm Wave transceivers and for verification of custom planar devices using standard waveguide test equipment.