用于小型化宽带环境射频能量收集天线的新型人工电磁材料研究

Ambient RF energy-harvesting is an important way to achieve self-supply of power by the new generation of low/ultra-low power consumption wireless network. How to design the energy-harvesting antenna that can harvest ambient RF energy with low power density, wide frequency spectrum and strong fluctuation as well as statisfy multiple restraints such as size and geometric configuration remains a key technical issue to be addressed immediately. This project aims at miniaturized broadband adaptive energy-harvesting antenna and focuses investigation on new planar artificial electromagnetic material. We examine the mechanism of miniaturized broadband material, and employ dual/multiple resonance introduced by dual plane structure to resolve the conflict of size and bandwidth so as to keep both size and bandwidth into control. Then, we put forth a method to analyze the electromagnetic features of miniaturized broadband material in bending condition and establish an equivalent circuit model for flexible material performance characterization. Finally, we design two kinds of integrated new material miniaturized broadband antenna to analyze their far-field pattern when bended differently. We also build a test and verification platform where energy-harvesting experiment in many real circumstances is conducted to validate the correctness and feasibility of the analysis and provide theoretical and technical support for maximum ambient RF energy harvesting.

环境射频能量收集是新一代低功耗/超低功耗无线网络实现自供电的重要手段。如何设计出匹配环境射频能量功率密度低、频率分布广、波动性强的分布特征，同时满足可用空间尺寸、几何构型等多重约束条件的收集天线是亟需解决的关键技术问题。本项目以小型化宽带自适应收集天线为导向，聚焦新型平面人工电磁材料这一有效途径开展研究工作，具体包括：研究小型化宽带材料的实现机理，提出通过双层结构引入的双/多重谐振来克服传统材料尺寸和带宽的相互制约，实现材料尺寸和带宽的双重可控；提出小型化宽带材料在弯曲条件下的电磁特性分析方法，建立用于柔性材料性能表征的等效电路模型；设计两类集成新型材料的小型化宽带天线，分析两类天线在不同弯曲时的方向图特性，搭建测试验证平台，进行多种实际场景下的能量收集实验，验证理论分析的正确性和可行性，为环境射频能量的最佳收集提供理论支撑和技术保障。

本项目深入研究了平面人工电磁结构设计方法及其在高性能低剖面天线等方面的相关应用。首先，提出通过控制结构单元间的等效电容产生多重谐振，成功拓宽了传统结构的同相位反射带宽；提出通过双层结构构造双/多重谐振实现小型化宽带材料的新途径，构建了相应的等效分析模型；构造了一种具有线-圆极化转换的宽带超表面，在4.5个倍频程内实现电磁波的极化调控。其次，系统研究了低输入功率条件下的高效宽带整流电路设计方法，利用阻抗调节单元、双频匹配网络等手段，实现了多型高灵敏度宽带整流电路，并给出了指导电路设计的完整闭合解析式。最后，探索了人工电磁结构在高收发隔离天线、低剖面宽带天线、宽角扫描天线、天线阵列RCS减缩等方向的应用，其中，基于人工电磁结构的共口径收发隔离天线、单馈点双频双圆极化天线及大角度扫描天线阵列成功获得飞行器平台应用。在整个研究期内，共申请发表期刊论文8篇，会议论文7篇，发明专利3项，协助培养硕士生5名。