140-GHz Low-Loss Wideband Air-Filled Waveguide Transition Integrated in LTCC and The Antenna Application

Air-filled waveguide integrated in Low Temperature Co-fired Ceramic (LTCC) has advantages of low loss and high efficiency compared with the SIW using dielectric substrate-filled waveguide and is suitable for the design of sub-millimeter wave and terahertz circuits and components. In this paper, a 140 GHz low-loss integrated air-filled waveguide is designed in LTCC, and to feed the integrated air-filled waveguide, a wideband transition from metal rectangular waveguide to LTCC air-filled waveguide is presented using a stage impedance matching structure based on the LTCC manufacture process technology. Moreover, a horn antenna integrated in LTCC is designed at 140-GHz band and fed by the low-loss integrated air-filled waveguide. To obtain higher gain, a dielectric loaded SIW stage horn antenna is designed. The transition and antenna show good performance and demonstrate the application potential over the sub-millimeter wave and terahertz frequencies of integrated air-filled waveguide in LTCC.