Design of a wideband phased array using true-time-delay and phase-shifter (TTD-PS) hybrid beamforming for beam squint mitigation

This paper designs a wideband phased array using a hybrid beamforming architecture that employs true-time-delay (TTD) circuits at the subarray level and phase shifters (PS) at the element level to effectively mitigate beam squint. For a practical demonstration, a 1024-element large-scale array is constructed by tiling four 256-element Ku-band phased array panels, which are fed by four TTD chips. An experimental comparison is conducted between two configurations: a conventional architecture relying solely on internal phase shifters for beam steering, and the proposed hybrid architecture. The experimental results demonstrate that at a 60$^\circ$ scan angle, the proposed architecture reduces the maximum beam pointing error across an 800 MHz bandwidth from $\pm$3.5$^\circ$ to $\pm$1$^\circ$. This significant improvement in scan dispersion characteristics directly translates to enhanced communication quality: when transmitting a 600 MHz bandwidth 64QAM signal, the system's error vector magnitude (EVM) improves from an unacceptable $<$7% to $<$2%. This work validates the effectiveness of the hybrid architecture for building scalable, high-performance, large-aperture phased array systems, offering a critical technical pathway for the development of next-generation satellite communication and radar systems.