Novel $W$ -Band LTCC Transition From Microstrip Line to Ridge Gap Waveguide and its Application in 77/79 GHz Antenna Array

An ultra-wideband transition from microstrip line to ridge gap waveguide (GWG) is proposed for W-band system integration with antenna array and a transceiver. Substrate integrated waveguide bridge is used in the proposed transition for electromagnet wave propagation between microstrip line and ridge GWG, which can realize impedance matching for a wideband frequency range. Back-to-back transition prototypes are fabricated by the low-temperature co-fired ceramic (LTCC) technique, and the probe measurement results show that the transition can work at W-band. Moreover, the application of the proposed transition in a LTCC slot antenna array with magnetic coupling ridge GWG feeding network operated at 77/79 GHz is studied comprehensively. The antenna performance measurements demonstrate that the proposed transition has a potential massive application in the GWG active antennas.