基于缝隙背腔馈电的全息表面相控阵天线

The holographic surface phased array antenna based on back cavity feeder with slots, can realize beam scanning performance by encoding the diodes states to modulate the electromagnetic properties of surface. Traditional phased array antennas require large number of phase shifters or digital transceiver modules, resulting in high complexity and cost. In contrast, only single transceiver channel is needed in proposed phased array antenna with a simple control structure, which can be processed by cost-effective PCB technology, greatly reducing the cost of the phased array antenna. In addition, the antenna has low profile and high integration level, which can be used in a wide applications. This project will address the bottleneck problems of the proposed antenna, namely the high loss of the surface element, poor consistency of the excitation amplitude and high sidelobe level. Firstly, an elliptical complimentary electric-LC (cELC) metamatrial resonator element is illustrated to reduce the metal ohmic loss when resonating. Subsequently, this element is designed to be fed through a cavity from the waveguide slot, which can reduce the ohmic loss in diode for non-resonant case. In order to evaluate the consistency of excitation amplitude, probe arrays are introduced to record the field of the elements at different locations. By dividing the whole area to several regions, calibrations can be employed by regions rather than by each individual element. Finally, an optimization algorithm for holographic surface coding is proposed to suppress the sidelobe level. The work to solve the above three key issues will promote the practical development of the proposed phased array antenna.

课题提出了基于缝隙背腔馈电的全息表面相控阵天线，其通过对加载的二极管开关进行编码可调控界面的电磁属性，从而实现波束扫描。传统相控阵天线需要较多的移相器或者数字收发通道，设计复杂、成本较高。而该相控阵天线仅需单个收发通道，控制方式简单，可用印刷电路板（PCB）加工工艺，极大地降低了相控阵天线的成本。此外，天线剖面较低，可集成化高，适用范围较广。课题将围绕该类型天线存在的单元损耗大、单元激励幅度一致性差以及旁瓣较高的问题而开展研究。首先，设计椭圆形的互补电感电容超材料谐振单元（cELC）以降低单元谐振时的金属欧姆损耗，在此基础上将单元置于波导缝隙背腔上，减少非谐振时的二极管欧姆损耗。对单元激励幅度一致性的评估主要通过引入探针阵列来记录不同位置表面单元的场强，一致性校准则采用分区域补偿的方法。最后，课题提出了抑制旁瓣的全息表面编码优化算法。项目对三个关键问题的研究可推动该类相控阵天线的实用化。

课题针对低剖面低成本相控阵天线需求，开展了缝隙背腔馈电的全息表面相控阵天线技术研究。针对该类天线存在的单元损耗大的问题，首先研究了低损耗的椭圆形的互补电感电容超材料谐振全息表面单元；针对单元激励幅度一致性差的问题，评估分析了全息表面相控阵天线单元的激励一致性问题，并提出了区域补偿的解决方案；针对离散全息表面天线存在的旁较高的问题，通过引进随机相位的干扰抑制因子，实现了旁瓣和栅瓣的抑制；加工制作了一款64单元背馈式全息表面天线单元，馈电简单，可实现波束扫描功能。此外，设计加工了1款16单元的贴片式全息表面天线，其相对带宽较宽。项目期间累计发表了6篇SCI论文，3篇会议论文，培养了3名研究生。该课题研制的波束扫描天线，仅需单个收发通道，控制方式简单，天线剖面较低，可用印刷电路板（PCB）工艺加工，性价比高，有望推动超材料天线的实用化。