基于空气填充等效媒质的MEMS体硅集成太赫兹无源多波束天线

Multibeam systems are specifically required in terahertz communication, which has attracted the attentions of many countries. The passive multibeam systems are especially suitable to be applied in terahertz band, because of the balance in performance, complexity and cost. However, the terahertz passive multibeam antennas are faced with the major problems of high loss, low efficiency and low integration level. It is necessary to explore the new transmission medium, new multibeam generation mechanisms and new integration methods. Therefore, this project introduces the bulk-silicon microelectromechanical system (MEMS) techniques, and proposes an idea for constructing terahertz passive multibeam antennas based on the air-filled effective medium. The effective medium is constructed by electromagnetic crystals consisting of metallic periodic structures, and the effective dielectric properties are extracted by dispersion analysis. The functions of transmission, amplitude control and phase control based on the effective medium are studied. Furthermore, the mechanisms of terahertz multibeam wavefront generation are discussed based on the principles of matrix network and gradient-index lens. Considering the matching of functions, modes and structures, we research the integrated design methods of the terahertz passive multibeam antennas, and verify the methods by experimental realization. This project aims to achieve a solution of high-performance, easily integrated and cost-effective terahertz multibeam antennas, supporting the significant applications such as multi-user high-speed communication.

太赫兹通信技术已引起多国重视，且太赫兹通信系统有明确的多波束需求。在太赫兹频段，无源多波束系统在性能、复杂度、成本等方面更为平衡，具有实际应用价值。但太赫兹无源多波束天线当前面临损耗大、效率低、集成度低的突出问题，亟需探索新的传输媒质、多波束形成机理和集成实现思路。因此，本项目提出一种利用微机电系统(MEMS)体硅集成的，基于空气填充等效媒质的太赫兹无源多波束天线构建理念与方法。采用金属周期性结构构建电磁晶体，进行色散分析，提取等效介电性能，研究其太赫兹波传输和幅度相位调控功能；进一步，结合矩阵网络原理和非均匀等效折射率透镜原理，探讨太赫兹多波束等相位波前形成机理；融合功能匹配、模式匹配、结构匹配，研究太赫兹无源多波束天线的集成化设计方法，并进行MEMS体硅工艺制备和测试验证。获得具有自主知识产权的高性能易集成太赫兹无源多波束天线解决方案，支撑多用户高速通信等重要太赫兹应用。

本项目面向太赫兹通信背景，针对太赫兹空间高质量多信道构建需求，为解决太赫兹多波束辐射前端面临的性能、复杂度、集成度等关键问题，开展了一系列研究。首先，为解决太赫兹低损耗传输媒质和幅相调控问题，采用金属周期性结构构建了电磁晶体，进行了色散分析，提取了等效介电性能，研究了其传输和幅度相位调控功能；第二，为攻克太赫兹多波束形成机理，采用非均匀等效折射率透镜和周期漏波阵列原理，探讨了适用于太赫兹频段的多波束等相位波前形成方法；第三，为解决太赫兹多波束天线中功能网络与外部空间综合高效匹配问题，融合功能匹配、模式匹配、结构匹配，研究了太赫兹无源多波束天线的集成化设计方法，并进行了微纳工艺制备和测试验证。主要成果方面，第一，针对全金属梯度折射率透镜多波束天线的天馈一体化集成难题，提出了透镜-波导的结构新方案，实现了无过渡结构的高集成；并进一步提出了各向异性龙勃-麦克斯韦鱼眼透镜，具有辐射-传输功能复合的特点；第二，针对透镜多波束天线面临的多波束覆盖范围受限问题，提出了一种新型的全金属部分麦克斯韦鱼眼透镜天线，获得了一维半空间多波束覆盖；第三，针对全金属漏波天线频率扫描范围窄、扫描率小的问题，提出了匹配加载方法以实现半空间连续扫描，并提出了色散控制方法以在有限频带内获得更大的扫描角度；第四，针对300GHz以上太赫兹频段多波束天线的欠缺，提出了利用微纳尺寸精度增材制造技术构建透镜多波束天线的方法，实现了355GHz太赫兹表面波透镜多波束天线样件，并通过测试验证了该方法的可行性。获得了创新性的高性能易集成太赫兹无源多波束天线解决方案，为太赫兹多终端高速通信等重要应用奠定了理论与技术基础。