面向“低小慢”目标探测的微波光子MIMO雷达关键技术研究

To deal with the threatens caused by low-flying targets with small size and low velocity, and solve the difficulties to detect such targets, a microwave photonic multiple input multiple output (MIMO) radar is proposed and its key techniques are investigated in this project. The key techniques and advantages of the proposed radar are as follows. Firstly, by applying harmonic-and-noise-suppressed high-order microwave photonic frequency multiplication, high-conversion-efficiency and large-dynamic-range microwave frequency mixing, and optical wavelength division multiplexing, the proposed radar can have a large operation bandwidth, and thus a high range resolution can be achieved. Secondly, through multi-dimensional target detection and fusion in spatial domain and spectral domain based on the orthogonal frequency division multiplexing MIMO mechanism, a high performance for target detection and parameter estimation can be obtained. Thirdly, multi-channel de-chirping and separation are realized based on broadband microwave photonic frequency mixing, which enables the capability for real-time signal processing and target detection. In this project, the theory, mathematical model, and digital signal processing method of the microwave photonic MIMO radar will be investigated. Numerical simulations will be implemented before experimental investigation of the target detection performance by the microwave photonic MIMO radar. A 4 x 4 microwave photonic MIMO radar system will be established, and the goal is to detect and track small targets with a radar cross session as low as 0.01 square meters in real time within a detection range of 3 km. This project will solve the problems in high-resolution, multi-dimensional and real-time target detection, and provide technique support in the detection of low-flying targets with small size and low velocity.

为应对“低小慢”目标对低空域安全的威胁，解决其难以探测的问题，本项目提出一种面向“低小慢”目标探测的微波光子MIMO雷达并研究其关键技术。此雷达的关键技术与创新之处为：①通过抑制谐波与噪声的微波光子高次倍频、高效率大动态的微波光子混频，结合光波分复用技术实现宽带工作，具有高分辨目标探测能力；②采用正交频分复用MIMO雷达机制实现空域与频域多维探测，通过空域与频域信息融合实现高性能目标检测与参数估计；③借助微波光子混频同时实现多通道回波去斜与分离，具备实时信号处理与实时探测能力。本项目将研究微波光子MIMO雷达理论、模型与信号处理方法，并在仿真研究的基础上搭建4发4收微波光子MIMO雷达系统开展实验研究，实现对3km范围内雷达散射截面低至0.01平方米的“低小慢”目标的实时探测与追踪。本项目的研究能解决对“低小慢”目标进行高分辨、多维度、实时探测的难题，为此类目标的探测提供有力的技术支撑。

对小型无人机等“低小慢”目标探测是雷达技术的难点，尤其针对无人机集群中的个体目标高分辨探测。本项目主要研究面向“低小慢”目标探测的微波光子MIMO雷达关键技术，旨在借助微波光子技术的大带宽工作能力提升雷达距离分辨能力，借助MIMO阵列技术提升方位或角度分辨能力。主要开展了基于电光调制非线性高次倍频的雷达线性调频信号产生技术研究，基于微波光子混频的宽带回波去斜技术研究、微波光子MIMO雷达架构及数字信号处理方法研究，以及微波光子MIMO雷达高分辨探测与成像实验研究。建立了正交频分复用与时分复用微波光子MIMO雷达的数学模型与系统设计方法，完成了微波光子MIMO雷达目标探测与成像的仿真研究，分别研制了正交频分复用微波光子MIMO雷达演示系统与正交时分复用微波光子MIMO雷达演示系统，其中频分复用微波光子MIMO雷达采用4发4收阵列，单通道带宽4GHz，实现雷达探测的距离分辨率3.75cm，时分复用微波光子MIMO雷达采用4发8收阵列，单通道带宽8GHz，实现雷达探测的距离分辨率2cm。研制的微波光子MIMO雷达实验系统实孔径角度分辨率最高达到1.1°。基于微波光子MIMO雷达实验系统，完成了对小型无人机目标的高分辨数字波束扫描成像与逆合成孔径雷达成像。本项目的研究成果为解决“低小慢”目标的高分辨探测难题提供了重要技术支撑，其科学意义在于丰富微波光子信号产生、处理与阵列的理论与技术体系，进一步推进微波光子技术与雷达技术的交叉融合与实用化发展。