针对现有多输入多输出（multiple input multiple output,MIMO）雷达互耦率高、自由度低的问题，提出了一种低互耦率、高自由度的展开增广互质阵MIMO雷达设计方式。首先在收发两端分别部署展开增广互质阵列。然后通过引入稀疏扩展因子，使展开增广互质阵列子阵的阵元间隔得到扩展，并得到所提出的展开增广互质MIMO雷达阵元位置的闭式表达式。随后通过广义和差联合阵列的概念，详细推导出了雷达的连续自由度和总自由度的闭式解。最后通过基于空间平滑的多重信号分类方法得到波达方向（direction of arrival,DOA）估计。与其他互质MIMO雷达结构相比，所提出的展开增广互质MIMO雷达能够获得更多的连续自由度并具有更低的互耦率。仿真结果验证了所提出的雷达结构在DOA估计方面的有效性和优势。
Aiming at the problem of high mutual coupling rate and low degree of freedom (DOF) of existing multiple input multiple output (MIMO) radar, an unfolded augmented co-prime MIMO radar is proposed in this paper. First, the unfolded augmented co-prime array is deployed in both transmitter and receiver. Then, by introducing the sparse expansion factor, the inter-element spacing of different subarrays in unfolded augmented co-prime array is extended, and the closed-form expression of the position set for the unfolded augmented co-prime MIMO radar is obtained. Then, the generalized sum and different co-array (GSDC) concept is used to derive the closed-form solutions of continuous DOF and total DOF. Finally, the direction of arrival (DOA) is obtained by spatial smoothing multiple signal classification (MUSIC) method. Compared with other co-prime MIMO radar structures, the proposed MIMO radar offers higher DOF and lower mutual rate. Simulation results verify the effectiveness and advantages of the proposed radar structure in DOA estimation.
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