基于液晶材料的宽带平面反射阵波束扫描机理研究

Radars in special field, satellite communications and large-scale deep-space detection systems require antennas with strong anti-interference and communication distances. Although traditional beam scanning planar reflector array antennas can meet the above system requirements, it has some shortcomings of narrow bandwidth and broadband phase mismatch of array elements. In this program, according to the tuning characteristics of the liquid crystal material, the reflective phase of the array element is controlled by loading the reflective cell of the liquid crystal material, thereby realizing the design of the high-performance broadband beam scanning planar reflective array. This program will carry out the following research: establish a physical characteristic model of liquid crystal material under large-signal excitation and a key parameter equivalent model that affects the performance of "liquid crystal cell structure", and provide a theoretical basis for the rapid design of a broadband planar reflective array of liquid crystal materials. The use of liquid crystal material with large anisotropy and multi-resonant reflector structure, combined with phase real-time delay technology, to broaden the working bandwidth of the reflective array. Taking the phase compensation method based on the phase information of the incident field, a precise beam scanning control is achieved by real-time independent bias control of the liquid crystal material loaded in each unit of the reflection front. In combination with numerical analysis and theoretical analysis, a liquid crystal broadband planar reflection array electrically regulated dynamic circuit model is established. The research results of this program are of great significance to the development of liquid crystal antenna arrays.

特殊领域雷达、卫星通信以及大规模深空探测等系统要求天线具有抗干扰性强、通信距离远等功能。传统波束扫描平面反射阵天线虽可满足以上系统需求，但存在带宽窄、阵元宽带相位失配等缺陷。本课题根据液晶材料的调谐特性，通过加载液晶材料的反射单元来实现阵元反射相位的调控，进而实现高性能宽带波束扫描平面反射阵设计。本课题将开展以下研究：建立液晶材料在大信号激励下的物理特性模型及影响“液晶单元结构”性能的关键参量等效模型，为快速设计液晶材料宽带平面反射阵提供理论依据；采用各向异性较大的液晶材料及多谐振反射单元结构，结合单元相位实时延迟技术，提升反射阵工作带宽；采取基于入射场相位信息的相位综合补偿法，通过对反射阵面每个单元所加载的液晶材料进行实时相互独立偏压控制，从而实现精准波束扫描控制；结合数值算法与理论分析，建立液晶宽带平面反射阵电调控动态电路模型。本项目的研究成果对促进液晶天线阵的发展具有重要意义。

特殊领域雷达、卫星通信以及大规模深空探测等系统要求天线具有抗干扰性强、通信距离远等功能。传统波束扫描平面反射阵天线虽可满足以上系统需求，但存在带宽窄、阵元宽带相位失配等缺陷。本课题根据液晶材料的调谐特性，通过加载液晶材料的反射单元来实现阵元反射相位的调控，进而实现高性能宽带波束扫描平面反射阵设计。具体内容包括：.1.通过圆片谐振法和互补开口谐振环微带谐振传感器两种方法研究了大信号激励下液晶材料在微波频段的介电常数，通过圆片谐振法中谐振器的品质因数Q研究大信号激励下液晶材料在微波频段的介电损耗特性，通过偏光干涉法中液晶层的双折射率研究大信号激励下液晶材料在微波频段的偏振特性。已完成圆片谐振法和偏光干涉法的总结，并处理分析数据得到大信号激励下液晶材料在微波频段的介电损耗特性和偏振特性。.2.开展了基于液晶材料的平面反射阵天线设计，并针对窄带问题将真实时延技术引入到平面反射阵天线单元设计中，研究基于液晶材料反射阵的宽带化技术，完成了反射阵单元结构的仿真设计，并对相应单元进行加工测试分析。.3.针对平面反射阵单元提出了基于真实时延的液晶平面反射阵天线单元，设计了一个工作在K波段的平面反射阵天线，测试结果表明，在半功率束宽（HPBW）为4.75°、旁瓣电平小于3dB的情况下，天线最大增益为20.2dBi，通过矩阵键盘控制平面反射阵天线各单元输入偏压值，主波束方向可实现二维相扫，增益变化范围小于4.3 dB，最大可覆盖45°的角度范围。