应用于毫米波段的宽带波束调控超表面设计

毫米波段因其较高的数据传输速率和较大的容量而备受关注。为满足现代通信系统对宽带、波束偏转和高辐射效率等天线需求，本文提出了一种工作在88.5～94.6 GHz频带范围内的石墨烯-金属复合结构超表面。该超表面通过调节石墨烯的费米能级，对超表面单元的反射相位进行实时调控编码。调整金属层结构尺寸，可以调制不同编码状态下超表面单元的相位、幅度响应以及编码频段范围。经优化设计，在石墨烯费米能级分别为0 eV和1 eV时，编码超表面单元在88.5～94.6 GHz的宽频带内具有180°±20°的反射相位差，并且反射幅度均大于0.7。利用该单元设计了7×7的超表面，通过合理排布编码单元，可对毫米波段波束进行偏转和多波束切换等动态调控。实验结果显示，单波束最大偏转角度可达105°(-55°～50°),且可实现1～5个波束的切换。该超表面为多功能天线设计提供了新的解决方案，在高速无线局域网、车载雷达、卫星通信等领域具有潜在的应用价值，对毫米波段通信技术的发展具有重要意义。

Design of a Broadband Beam-Modulated Metasurface for Millimeter-Wave Applications

Millimeter-wave applications are receiving considerable attention due to their high data transmission rates and large capacity. To meet the demands of modern communication systems for wide bandwidth, beamforming, and high radiation efficiency, a graphene-metal composite metasurface operating in the 88.5-94.6 GHz frequency range is proposed in this paper. The metasurface enables real-time beamforming control of its elements by adjusting the Fermi level of graphene. By optimizing the dimensions of the metal layer, the metasurface elements exhibit different phase and amplitude responses, as well as coding frequency ranges for various coding states. After optimized design, the encoded metasurface unit exhibits a reflection phase difference of 180 °± 20° in the broad frequency band of 88.5-94.6 GHz, at graphene Fermi levels of 0 eV and 1 eV, respectively, with all reflection amplitudes being greater than 0.7. Utilizing the unit design, the metasurface allows dynamic control of millimeter-wave beams, including beam steering and multi-beam switching, achieved by arranging the coding elements appropriately. Experimental results demonstrate that the maximum deflection angle of a single beam can be up to 105° (-55° to 50°) and the switching from 1 beam to 5 beams can be realized. The proposed metasurface presents a novel solution for multifunctional antenna design, holding potential applications in high-speed wireless local area networks, vehicular radar systems, satellite communications, and other fields. Its significance lies in advancing millimeter-wave communication technology.