阵列LFMCW SAR模糊函数分析

Ambiguity Function Analysis of Array LFMCW SAR

模糊函数(AF)可以描述雷达信号决定的测量精度、杂波抑制特性及信号分辨特性。常规雷达模糊函数是基于时延和多普勒频率的函数,不适用于SAR分辨特性的分析。本文基于常规SAR广义模糊函数(GAF)理论,推导了线性调频连续波(LFMCW)SAR GAF,并进一步分析了前视和下视阵列LFMCW SAR两种典型阵列SAR的模糊函数。根据常规LFMCW SAR模糊函数研究了前视阵列LFMCW SAR GAF,针对下视阵列SAR特点,借鉴了编队卫星SAR模糊函数的分析方法对下视阵列LFMCW SAR GAF进行建模,并结合模糊因子分析了上述两种体制的分辨特性。本文利用模糊函数对阵列LFMCW SAR的分析方法,可为深入理解前视和下视阵列SAR的参数及系统设计提供参考。

Ambiguity Function（AF） can describe measuring accuracy,clutter suppression characteristic and signal resolution characteristic determined by radar signal.AF of conventional radar based on time delay and Doppler frequency of radar signal is not appropriate for resolution analysis of SAR.This paper deduces Generalized Ambiguity Function（GAF） of Linear Frequency Modulated Continuous Wave（LFMCW） SAR based on GAF theory of conventional SAR.AF of two new kinds of typical array LFMCW SAR system： forward-looking（FL） array LFMCW SAR and downward-looking（DL） array LFMCW SAR are analyzed further.GAF of FL array LFMCW SAR is investigated according to AF of conventional LFMCW SAR.According to the feature of DL array SAR,and inspired by AF of formation flying satellites SAR whose structure is similar to that of DL array SAR,GAF of DL array LFMCW SAR is modeled. Ambiguity factors are combined to analyze resolution characteristic of the above two kinds of system.The analyzing approach based on AF for array LFMCW SAR proposed in this paper can provide valuable reference for comprehension of parameter choice and system design of FL and DL array SAR.