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 millimeter wave (mmWave) beamforming networks that scan in both azimuth and elevation plane. 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 × V elements. Contrary to other 2D scanning multibeam networks found in the literature, the proposed design is (to our knowledge) the first planar, true-time-delay implementation. Notably, a formulation for designing M -beam ( H × V ) antenna networks is derived, and an example of an 8-beam 2 × 4-antenna network is prototyped to validate the performance of the proposed approach. The measurements show good agreement with simulations, validating the proposed multi-beam 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 GHz to 40 GHz range of instantaneous bandwidth.