A new dual-broadband liquid-crystal programmable metasurface (LCPM) has been proposed to support terahertz wireless communications in non-line-of-sight scenarios, according to a study published in Engineering. The device enables flexible beam manipulation across two frequency bands and helps maintain stable links when direct line‑of‑sight paths are blocked, supporting high-speed data transmission under various modulation schemes.
Terahertz communication is regarded as a key spectrum technology for future wireless networks, offering large contiguous bandwidth for ultra-high data rates and low latency. However, terahertz waves suffer from high propagation, diffraction, and penetration losses, making communication unreliable in non-line-of-sight environments. Traditional passive reflecting surfaces rely on specular reflection and cannot adapt to dynamic user locations, while active reconfigurable intelligent surfaces based on semiconductors often face high costs and fabrication challenges at terahertz frequencies. The LCPM developed in this work uses liquid crystal as the tuning material, featuring low cost, low power consumption, large phase-tuning range, and scalability for large-scale arrays.
The metasurface employs an anisotropic meta-atom design that responds differently to orthogonal polarizations. It operates in the W band covering 94 GHz for x-polarized incidence and the D band covering 140 GHz for y-polarized incidence. The meta-atom structure supports 1-bit phase coding with a phase difference within 180°±20° across targeted broadband ranges. The full metasurface array consists of 50×50 meta-atoms, organized into 25×25 independently controllable super-elements. Numerical simulations and experimental measurements confirm that the LCPM can realize dual-beam steering, single-beam scanning, and dual-band independent beam control through partition coding schemes.
Researchers built a terahertz wireless communication system to evaluate the LCPM in blocked link conditions. In tests where line-of-sight propagation was obstructed, the LCPM dynamically regulated wireless channels in three-dimensional space by adjusting coding patterns, establishing stable connections that could not be maintained with a fixed passive reflecting surface. The system supported QPSK, 16-QAM, and 64-QAM modulations in both operating bands, achieving real-time high-speed video transmission. Broadband performance was verified over a 10-GHz bandwidth in the D band, with consistent error vector magnitude values across the operating range. Long-distance measurements showed reliable communication at extended propagation lengths, demonstrating the metasurface's ability to enhance coverage and link stability.
The experimental results validate the feasibility of using the liquid-crystal programmable metasurface for terahertz wireless communications. The dual‑broadband operation, programmable beam control, and stable non-line-of-sight links lay a foundation for developing ubiquitous terahertz networks. Future work will focus on upgrading phase coding to higher bit depths, reducing liquid-crystal thickness for faster response, and integrating sensing and communication functions into intelligent metasurface systems.
The paper "A Dual-Broadband Liquid-Crystal Programmable Metasurface and Its Application in Terahertz Wireless Communications," is authored by Yuan Fu, Yuanbo Li, Xiaojian Fu, Lu Xu, Yujie Liu, Qun Yan Zhou, Jun Yang, Chong Han, Jun Yan Dai, Qiang Cheng, Tie Jun Cui. Full text of the open access paper: https://doi.org/10.1016/j.eng.2025.08.040
