天线阵列编码合成孔径成像

Synthetic Aperture Imaging of Antenna Array Coded

合成孔径雷达(SAR)方位理论分辨率为天线长度的二分之一,使得SAR高分辨率、远距离成像对天线的要求相互矛盾。该文提出了对天线阵列编码的合成孔径成像方法,通过将长天线分解为子阵、发射不同的信号进行阵列编码、协同工作,提高空间能量利用率,实现子阵小天线的高分辨率以及全阵列长天线的高增益,从而解决了高分辨率与远距离成像难以同时兼顾的问题。在介绍阵列编码基本概念的基础上,给出了阵列编码雷达成像模型及处理流程,对系统的分辨率、信噪比、脉冲重复频率(PRF)及距离方位模糊等性能进行了理论分析与探讨。在飞行测试实验中,用4个子阵获取了方位分辨率优于0.1 m、幅宽超过8 km的连续条带图像,打破了传统SAR采用聚束模式实现高分辨率时只能小范围成像的制约,新方法为解决传统SAR的原理限制问题提供了有效的途径。同时,通过阵列编码扩展了信号维度,为雷达系统能力的增强提供了技术基础。理论分析及实验结果验证了该文天线阵列编码方法的显著优势及工程实现的可行性。

The theoretical azimuth resolution of Synthetic Aperture Radar(SAR)is half the antenna length,presenting conflicting requirements on the antenna for SAR high-resolution and long-distance imaging.In this paper,a method for antenna array coding synthetic aperture imaging is proposed.By dividing long antennas into subarrays to work together,the space energy utilization rate can be improved,a high resolution of the small antennas of the subarrays and a high gain of the long antennas of the whole array are achieved,and the problem that it is difficult to balance high-resolution and far-distance imaging is solved.On the basis of introducing the basic concept of array coding,the imaging model and processing flow of array coding radar are given,and the system performance metrics,such as resolution,signal-to-noise ratio,Pulse Repetition Frequency(PRF),and range-azimuth ambiguity,are theoretically analyzed and discussed.In a flight test experiment,a 0.5 m antenna is divided into four sub-arrays,and a strip-map image with a resolution of 0.1 m and a swath width of 8 km is obtained,which breaks the restriction of small-area imaging when traditional SAR adopts the spotlight mode to achieve high resolution.This new method effectively solves the limitations of traditional SAR and extends the signal dimension,providing a technical basis for enhancing radar system capability.Theoretical analysis and experimental results verify the considerable advantages and engineering implementation feasibility of the proposed method.