Novel $W$ -Band Millimeter-Wave Transition From Microstrip Line to Groove Gap Waveguide for MMIC Integration and Antenna Application

For monolithic microwave integrated circuit integration and antenna application, a novel W-band millimeter-wave transition from microstrip line to groove gap waveguide (GWG) is proposed in this communication. The transition is achieved by a modified planar triangular microstrip patch resonator with an inner shorting via. To give a physical insight, E-field analysis is presented, and its working mechanism is similar to that of the passband filter based on coupled resonators. The proposed transition may contribute to a potential groove GWG application in the W-band radar and communication system. Finally, a back-to-back transition prototype is fabricated and assembled for measurement. To improve S11 of the prototype, a modified CPW probe pad is applied. Moreover, the influences on S11 and S21 of the conductor losses are given. The measured results show that there is an excellent transition passband from 90 to 99.5 GHz, in which frequency band, S11 is almost below -12 dB.