基于脉间捷变频的低空聚束SAR快速成像算法

doi:10.12305/j.issn.1001-506X.2026.07.10

摘要/Abstract

摘要：

针对低空聚束合成孔径雷达在复杂电磁环境下抗干扰能力不足的问题，提出一种基于脉间捷变频的快速极坐标格式算法（polar format algorithm，PFA）。首先，构建捷变频信号的波数域空变相位误差模型，揭示传统PFA失效机理。其次，提出多域联合补偿策略：在时域利用距离轴?载频联合补偿矩阵实现距离向主瓣完全相位补偿，抑制空变误差对旁瓣的耦合效应；在波数域设计自适应频谱恢复函数，消除捷变频导致的方位频谱偏移与泄露。仿真结果表明，所提算法在保留PFA计算效率与运动适应性的基础上，点目标峰值旁瓣比与积分旁瓣比与固定载频PFA相比分别提升13.85 dB与14.26 dB，且抗干扰模式下虚假目标幅值衰减至真实目标的3.03%。所提算法计算量与固定载频PFA几乎相当，处理耗时仅增加12.20%。表明所提算法可为低空无人机载合成孔径雷达平台提供兼具高分辨实时成像与强抗干扰能力的解决方案。

关键词: 合成孔径雷达, 极坐标格式算法, 快速成像, 抗干扰, 脉间捷变频

Abstract:

A fast polar format algorithm （PFA） based on inter-pulse frequency agility is proposed to address the issue of insufficient anti-jamming capability of low-altitude spotlight synthetic aperture radar in complex electromagnetic environments. Firstly, a wavenumber domain spatially varying phase error model for frequency agility signals is constructed to reveal the failure mechanism of traditional PFA. Secondly, a multi domain joint compensation strategy is proposed: in the time domain, the distance axis carrier frequency joint compensation matrix is used to achieve complete phase compensation of the mainlobe in the distance direction, suppressing the coupling effect of spatially varying errors on sidelobes. An adaptive spectrum recovery function in the wavenumber domain is designed to eliminate azimuth spectrum offset and leakage caused by frequency agility. The simulation results show that the proposed algorithm improves the peak sidelobe ratio and integrated sidelobe ratio of point targets by 13.85 dB and 14.26 dB, respectively, compared to fixed carrier frequency PFA, while retaining PFA computational efficiency and motion adaptability. Moreover, in anti-jamming mode, the amplitude of false targets attenuates to 3.03% of that of real targets. The computational complexity of the proposed algorithm is almost equivalent to that of the fixed carrier frequency PFA, with a processing time increase of only 12.20%. This indicates that the proposed algorithm can provide a solution for low-altitude unmanned aerial vehicle synthetic aperture radar platforms that combines high-resolution real-time imaging and strong anti-jamming capabilities.

Key words: synthetic aperture radar （SAR）, polar format algorithm （PFA）, fast imaging, anti-jamming, inter-pulse frequency agility （IFA）

中图分类号:

TN 974

金梓涵, 江率, 刘彦斌, 曹越, 喻忠军. 基于脉间捷变频的低空聚束SAR快速成像算法[J]. 系统工程与电子技术, 2026, 48(7): 2229-2240.

Zihan JIN, Shuai JIANG, Yanbin LIU, Yue CAO, Zhongjun YU. Low-altitude spotlight SAR fast imaging algorithm based on inter-pulse frequency agility[J]. Systems Engineering and Electronics, 2026, 48(7): 2229-2240.

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参数	参数值
载频/GHz	5.4
捷变范围/MHz	200/0 （固定载频）
合成孔径时间/s	1.309 5
波长/m	0.055 6
飞机设计时速/（m/s）	100
发射脉冲宽度/μs	4
信号带宽/MHz	200
斜视角/（°）	0（正侧视）
平台高度/m	800
脉冲重复频率/Hz	1 000

点目标	PSLR		ISLR
点目标	距离向	方位向	距离向	方位向
A点（IFA-PFA）	−24.03	−14.43	−22.56	−10.38
A点（PFA）	−14.57	−15.27	−11.86	−10.22
B点（IFA-PFA）	−24.36	−13.60	−21.16	−9.71
B点（PFA）	−13.23	−13.34	−9.89	−9.78
C点（IFA-PFA）	−24.84	−16.94	−22.61	−11.25
C点（PFA）	−13.22	−17.64	−9.89	−11.75

算法	IFA-PFA	PFA
平均用时	2.856 5	2.545 7

图片	二维信息熵/dB	SSIM （对比真实模板）
图16（b）	6.195 77	0.394453439
图16（e）	8.130 87	0.362239322

算法	真实点幅值	干扰点幅值（平均）
PFA	1601.02	1596.77
IFA-PFA	1519.71	35.8896