Sub-Terahertz Fully Metallic Sliding-Aperture Wide-Angle-Multibeam Antenna Based on Mixed-Waveguide Phase Shifter Array

This letter presents an experimental realization of a sub-terahertz (sub-THz) fully metallic sliding-aperture multibeam antenna with a wide beam scanning range based on mixed-waveguide (mixed-WG) phase shifter array for the first time to the best of the authors' knowledge. To meet the requirements of wide scanning range without grating lobes, each mixed-WG phase shifter array is composed of a rectangular waveguide (WG) phase shifter and a double-ridge WG phase shifter, yielding a much smaller element spacing in the radiating aperture. To reduce the effect of the open boundary condition which damages the illuminating property from the edge port and causes worse scan loss, additional mixed-WGs are added symmetrically on both sides. The antenna is fed by nine rectangular WGs, serving nine independent beams. A ridged flare is added as a transition from the mixed-WG phase shifter array to free space, improving the radiation performance. A prototype operating within the band from 175 to 195 GHz is fabricated by high-precision computer numerical control (CNC) machining technique and experimentally verified. The measured results show good reflection coefficients below -15 dB at all ports, a best beam scanning range of ±52°, peak gains above 15.5 dBi, and scan loss better than 2.2 dB, agreeing well with simulation. This work demonstrates a novel feasible and reliable solution of waveguide-based fully metallic sub-THz multibeam antenna for the application demanding wide angle scanning.