基于可重构超表面结构的非衍射波束的方向调控研究

Non-diffractive beam, whose energy is not diffracted within the transmission distance, has an important application value for near-field microwave power transmission. However, the mechanism of the near-field electromagnetism control is not mature, and it is difficult for the non-diffractive beam to achieve the direction control at a fixed frequency. To solve this problem, the project aims at the microwave power transmission system with one transmitting antenna and multiple targeting antennas, and a new idea for the non-diffractive antenna design to control the beam direction is proposed. The detailed research is carried out as following: Firstly, the modulation function will be studied to produce the non-diffractive beam with low sidelobes. Then, the electromagnetic characteristics of the modulation function will be analyzed to determine the concrete form of the function, and the waste of power in the transmission will be reduced. Secondly, the mechanism of the electromagnetism control by using the metasurface structure will be thoroughly researched. Combined with the reconfigurable technology, the relationship between the switch state and the beam characteristics will be investigated, and the reconfigurable metasurface structure will be proposed for the electromagnetism control. Thirdly, based on the modulation function, by using the electromagnetic optimization algorithm, an optimal scheme for the layouts of the switches with biasing networks will be put forward to achieve the high power transmission, and the initial model of the non-diffractive antenna, which can be experimentally verified at microwave frequency, will be presented to manipulate the non-diffractive beam direction flexibly. This study is dedicated to the exploration on the mechanism of electromagnetism control, and provides a reliable technical way and method to achieve high efficiency spatial power transmission for multiple targeting antennas.

非衍射波束，在传输过程中能量具有非扩散特性，对于近场微波输能具有重要的应用价值。然而，近场电磁调控机理尚不成熟，在固定频率下非衍射波束的方向调控还难以实现。本项目围绕这一问题，针对一对多目标的微波输能系统，提出波束方向可调的非衍射天线研究新思路。具体研究内容如下：1.研究产生低旁瓣非衍射波束的调制函数，确定其函数形式，分析其调制函数的电磁特性，以减少波束传输能量浪费；2.研究超表面结构的电磁调控机理，引入可重构技术，分析可调器件的不同状态与波束特性之间的关系，从而提出电磁可调的可重构超表面结构；3.基于低旁瓣非衍射调制函数，采用电磁优化算法，以高能量主波束传输为目标，提出电调器件及其偏置电路的最佳布局方案，并在微波频段内提出经过实验验证的非衍射天线初始模型，最终实现非衍射波束方向灵活调控。该研究致力于探索电磁调控机理，为实现高效率多目标的空间能量传输提供可靠的技术途径和实现方法。

目前，近场电磁调控机理尚不成熟，在固定频率下非衍射波束的方向调控还难以实现。本项目旨在针对于一对多目标系统，研究超表面电磁可调理论和关键技术，为产生低旁瓣非衍射波束及实现波束方向调控的新方法提供可靠的理论依据、高效的设计方法及经过实验验证的若干初始模型。本项目研究取得的主要结论如下：1）引入Gauss函数，利用Gauss函数低旁瓣特性，提出Bessel-Gauss径向槽天线模型，实现低旁瓣非衍射波束；2）提出超表面电磁分析模型，采用超表面结构，分别实现三维空间上和二维表面波的非衍射波束偏折；3）采用可重构技术，建立可重构超表面漏波天线模型，在固定频率下实现了非衍射波束动态可调。本研究揭示了超表面电磁灵活调控机理，实现了低旁瓣非衍射波束，且波束灵活可调，开辟了非衍射天线新的研究方向和应用场景。