Wide-Angle Reflective Terahertz Beam Steering Metasurface Based on Cross-Polarization Conversion

The terahertz (THz) frequency range is considered an important spectrum for future 6G communication. However, the high propagation losses and poor penetration inherent to terahertz waves restricted its development. Wavefront manipulation techniques for beam steering to redirect the propagation directions are essential for mitigating these limitations. In this paper, cross-polarization conversion-based phase engineering for THz reflective beam steering is presented. This approach has the advantages of enabling quasi-linear phase response with sufficient phase shifting range and maintaining high reflection magnitudes over a wide frequency band. Furthermore, a four ports equivalent circuit is developed to explain the design principle and verify the effectiveness of the polarizers. As a result, the metasurfaces composed of the proposed unit cells achieve stable wide-angle beam steering with high reflection intensity and have continuous frequency-scanning capability. In addition, the metasurfaces are verified to support high-quality 16-QAM modulation with acceptable power penalty in a non-line-of-sight THz link.