A New Class of Full-Dimensional Planar True-Time-Delay Beamforming Networks

This work introduces a new class of low-cost, passive, planar, multibeam, true-time-delay (TTD) millimeter-wave (mmWave) beamforming networks that scan in both azimuth and elevation planes. Namely, the traditional Blass matrix topology, which is capable of exciting M beams in a linear array of N antenna elements, is redesigned to excite M beams in a planar array of H \times V elements. Contrary to other 2-D scanning multibeam networks found in the literature, the proposed design is (to our knowledge) the first planar, TTD implementation. Notably, a formulation for designing M -beam (H \times V) antenna networks is derived, and an example of an 8-beam 2 \times 4 antenna network is prototyped to validate the performance of the proposed approach. The measurements show good agreement with simulations, validating the proposed multibeam methodology. Specifically, our results demonstrate the capability of simultaneously generating 8 squint-free beams that can scan both the azimuth and elevation planes across the entire 24-40-GHz range of instantaneous bandwidth.