考虑到雷达阵列对多目标的分辨率大小是评价波达方向估计算法性能的重要因素,论文基于非均匀线阵模型从克拉美罗-界角度分析了不同信噪比下阵列对两目标的最小分辨率极限.首先推导了关于未知参数(电角度和噪声方差)的双源远场信号模型下非矩阵形式的闭式克拉美-罗界解析式.在此基础上,通过建立最小距离分辨率与克拉美-罗界之间的关系等式,并用泰勒展开等数学运算做近似处理,推导得到了阵列对两信源在正交和非正交情况下的最小距离分辨率极限公式,并进一步揭示了影响系统分辨率性能的物理因素,蒙特卡罗仿真结果验证了理论推导的正确性.该结论可作为评判非均匀阵列设计和衡量波达方向估计算法性能优劣的重要理论依据.%Considering the resolution of the radar array is an important performance measure for the directions-of-arrival (DOA) estimation algorithm, the minimum separation resolution limit (MSRL) from the perspective of the Cramér-Rao bound (CRB) is deduced based on the non-uniform linear array model and different signal-to-noise ratios.First, closed-form expressions of the CRB about the unknown parameters (electric angle and the noise variance) under two sources far-field signal model are derived.On this basis, the analytical expression of separation resolution limit is established by relating the resolution limit with the CRB.Through some mathematical approximate processing, an explicit analytical expression of this distance resolution limit is derived under orthogonal and non-orthogonal conditions.Simulation results verify the correctness of the theory.This conclusion can be used as the primary standard to evaluate the design of non-uniform array and performance of DOA estimation algorithm.
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