Systematic Broadband Design Paradigm of PCB Metagratings for Terahertz Beam Steering

Efficient terahertz (THz) beam steering is crucial for promoting next-generation wireless communication, radar, and imaging systems. While printed circuit board (PCB) type metagrating demonstrates powerful beam manipulation capabilities, the narrowband characteristic induced by the uniform atom distribution and single-frequency design presents a significant challenge for achieving broadband operation and high efficiency in THz. To address this issue, we propose a systematic broadband design paradigm leveraging nonuniform spatial arrangements. We treat the atom position as a free variable and establish a comprehensive database that maps the geometric parameters of atoms to frequency response and load-impedance density. By refining the fitness function of the particle swarm optimization algorithm, the broadband design problem is reformulated as a geometric parameter optimization task. Unlike conventional single-frequency optimization, our approach ensures stable beam steering across a 25% relative bandwidth. Finally, experimental validation is performed on prototypes fabricated via RF magnetron sputtering, which confirms the effectiveness of the proposed paradigm.