基于有源频率选择表面的可重构谐振腔天线研究

Resonant cavity antennas have been widely utilized in many applications owing to their intrinsic merits of high gain, simple feeding network, and ease of integration. However, the conventional architectures are unable to adjust themselves to complicated electromagnetic situations or task mode due to their fixed characteristics, such as frequency, beam, polarization, orbital angular momentum, etc. To meet the urgent demands of multi-functionality and software-defined characteristics of antenna by complex EM environment and diverse wireless systems, operating and controlling mechanism of reconfigurable antennas based on Fabry-Perot interference and tunability of diodes are investigated in this proposed project. The analysis model of active frequency selective surfaces loaded with diodes is built by combining full-wave EM method and equivalent circuit model firstly, and the impact of biasing status of diodes on the performance of scattering characteristics are analyzed. Active frequency selective surfaces loaded with diodes are utilized to construct reconfigurable partially reflective surface and tunable artificial magnetic conductor as superstrate and ground plane of cavity antenna. The approach to synthesize the aperture field distribution of cavity antenna under frequency-tuning, beam-steering and vortex mode-reconfigurable mode circumstances are derivated. The grouping and controlling methodology of diodes subject to different reconfigurable mode is explored. This project aims to broaden the tuning range of frequency, realize 2D beam scanning and generating mode-switchable vortex wave in the theory and technique domain.

谐振腔天线因增益较高、馈电简单、易于加工集成等优点而获得广泛应用，但传统的谐振腔天线具有固定的频率、波束、极化和轨道角动量等特征。鉴于电磁环境和无线系统对天线多功能与软件可定义的迫切需求，本课题拟开展对基于谐振腔干涉模型和二极管电调模型的可重构天线的调控机理研究。具体包括利用电磁场全波分析与等效电路模型建立加载PIN二极管和变容二极管的有源频率选择表面的分析模型，并量化二极管偏置状态对其散射特性的影响；利用有源频率选择表面构造可重构部分反射表面和可重构人工磁导体作为谐振腔天线的覆层和背板，依据谐振腔天线的干涉机制，揭示谐振腔天线在谐振频率、波束指向和涡旋模态可重构模式下的口径场综合方法与分布规律；探索谐振腔天线在不同可重构模式下二极管的分组与控制方式。本课题的研究旨在为可重构谐振腔天线在拓展频率调制范围、实现二维波束扫描、产生模态可控的涡旋电磁波方面提供一定的理论依据和技术途径。

随着无线系统的快速发展和电磁环境的复杂多变，在认知无线电等领域中，天线的性能需要根据电磁环境或任务模式的变化做出适应性调整，具有频率捷变、极化切换、波束切换或扫描等功能的可重构天线获得广泛应用。本项目结合法布里-珀罗干涉模型和基于二极管的可重构技术对基于有源超表面的可重构谐振腔天线展开研究。在项目开展过程中，以几何光学近似模型、切向等效网络模型和漏波模型为理论基础，对具有不同辐射特征（法向辐射的笔形波束、偏离法向辐射的笔形波束和偏离法向辐射的锥形波束）的谐振腔天线的分析方法进行了补充与拓展。利用几何光学简化分析模型研究了基于“锯齿分布”超表面的一维和二维倾斜波束无源谐振腔天线，并将其与切向等效网络模型结合，提出了加载变容二极管的频率和波束多功能可重构谐振腔天线的设计方法，分别实现了频率可重构、E面波束扫描、H面波束扫描和二维波束扫描，并且显著简化了直流偏置电路的独立控制通道数量，降低了成本。基于漏波模型和切向等效网络模型并结合微带天线腔模理论，提出了涡旋谐振腔天线的设计方案，改善了馈源的增益和波束发散角。本项目的研究结果为多功能软件可定义天线提供了一定的理论探索和技术验证。