Risley-Prism Metalens Antenna for On-Demand Beam Steering in Terahertz Sensing and Imaging

High-directivity beam steering critically overcomes severe path attenuation in terahertz (THz) links by enhancing equivalent isotropic radiated power (EIRP), sensing resolution, and field of view (FoV). Reconfigurable THz beamforming devices still confront challenges in steering coverage and precision, in loss mitigation, and particularly in array scalability requiring element-level tuning. Here, a horn-fed Risley-prism metalens antenna (RP-MLA) is developed to achieve high-gain THz beam steering over ±50° FoV. Two cascaded 3.1 in. aperture metasurfaces, patterned with prism/lens-like phase profiles on high-resistivity silicon wafer, are servo-driven to dynamically reconfigure the phase gradient for steering. An evaluation workflow is proposed to quantify steering efficiency and beam gain in electrically large RP-MLA arrays. The prototype demonstrates a peak gain of 38 dBi and beam-pointing accuracy 20 dB and a 3 dB gain roll-off at extreme steering angles. Active beam squint correction is realized over a −3 dB bandwidth of 320–370 GHz. The RP-MLA-enabled transceiver uniquely combines THz-aware adaptive beam alignment, concealed object imaging, and focal probing, delivering an integrated communication-sensing solution with a superior performance-to-cost ratio.