正交三偶极子阵列MIMO雷达近场目标定位
Near-Field Target Localization with a Three Orthogonal Dipole Array MIMO Radar
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摘要: 本文基于发射端和接收端都配备了正交三偶极子阵列的双基地多输入多输出(Multiple-Input Multiple-Output, MIMO)雷达系统,结合三线性分解提出了一种近场源多维参数估计算法。该算法首先利用接收端匹配滤波器的输出数据构建了一个三阶平行因子(Parallel Factor, PARAFAC)模型。同时为了加快算法的收敛速度以及避免所提算法对迭代的初值敏感,利用复平行因子分析(COMplex parallel FACtor analysis, COMFAC)算法来得到发射阵列和接收阵列导向矩阵的估计值。接着,根据发射阵列导向矩阵和接收阵列导向矩阵的结构特征得到每个目标的波离角(Direction-of-Departure, DOD)和波达角(Direction-of-Arrival, DOA)的粗估计值,并且基于双基地MIMO雷达阵列系统的几何关系得到从发射阵列到目标的距离以及从目标到接收阵列的距离的粗估计值。最后,基于得到的近场多维参数的粗估计值得到发射阵列和接收阵列的空间相位估计值,并进而从空间相位的估计值中得到更精确的DOD,DOA,从发射阵列到目标的距离和从目标到接收阵列的距离的精估计值。该算法适用于阵元间距为半波长的均匀线性阵列,相比于传统近场定位需满足阵元间隔为四分之一波长的前提,所提的MIMO阵列系统降低了阵列孔径损失,同时所提算法不需要进行谱峰搜索以及额外的参数配对操作。仿真结果表明,基于正交三偶极子阵列的MIMO雷达测向算法较传统标量阵列的算法具有较高的参数估计精度。Abstract: A near-field (NF) multiple parameter estimation algorithm based on trilinear decomposition is proposed for a bistatic multiple-input multiple-output (MIMO) radar system, configured with three orthogonal dipoles at the transmitter and receiver. The algorithm first constructs a third-order parallel factor (PARAFAC) model using the output data from the matched filter of the receiver. To accelerate the convergence speed and avoid initial value sensitivity for the proposed algorithm, the COMplex parallel FACtor analysis (COMFAC) algorithm is employed to estimate the steering matrices of the transmit and receive arrays. Subsequently, rough estimates of the unambiguous direction-of-departure (DOD) and direction-of-arrival (DOA) for each target are obtained from the structural characteristics of the transmit and receive array steering matrices, and based on the geometric relationships of the bistatic MIMO radar array system, rough estimates of the ranges from the transmit array to the target and from the target to the receive array are also obtained. Finally, based on the rough estimates of the NF multi-dimensional parameters, unambiguous spatial phase estimates of the transmit and receive arrays are obtained, leading to more precise estimates of the DOD, DOA, and the ranges from the transmit array to the target and from the target to the receive array. The proposed algorithm is applicable to uniform linear arrays with an element spacing of half a wavelength, and the proposed MIMO array system reduces array aperture loss compared to traditional NF localization, which requires a quarter-wavelength separation between array elements. Simultaneously, the proposed algorithm does not require spectral peak searching or additional parameter pairing operations. Simulation results show that the MIMO radar direction-finding algorithm based on the three orthogonal dipole arrays has higher parameter estimation accuracy compared to the traditional scalar array algorithm.