一种多尺度稀疏极化敏感阵列及其DOA估计方法

针对单个电磁矢量传感器(SS-EMVS)的孔径受限和传统稀疏阵列无法提供目标极化信息的问题,结合分离式电磁矢量传感器和稀疏阵列,提出了一种由SS-EMVS组成的多尺度稀疏极化敏感阵列。该阵列的阵列单元为1个完整的分离式电磁矢量传感器,沿y轴分布,整个阵列按阵元间距分为2个均匀子阵,而且这2个阵元间距都可以大于入射信号的半波长,从而构造一个多尺度稀疏极化敏感阵列以得到目标波达方向(DOA)的高精度估计值。该阵列结合了SS-EMVS可降低阵元互耦和稀疏阵列可扩大阵列孔径的优点,提高了目标DOA估计精度的同时降低了阵元互耦,并且对噪声也具备较好的鲁棒性。而在算法上,首先利用矢量叉积算法得到目标方向余弦的低精度无模糊估计值;其次根据2个子阵的空域旋转不变性得到目标方向余弦的高精度模糊估计值,针对这些方向余弦的估计值提出了一种多尺度解模糊算法,可得到目标方向余弦的高精度无模糊估计值;最后经过运算得到目标的高精度DOA的估计结果。仿真结果证明了所提阵列和算法的有效性。该阵列可应用于某些空间受限的实际应用场合中,如安装在飞行器上的传感器阵列,从而发挥电磁矢量传感器的单天线多分量的特点,也可以与MIMO雷达进行结合,借助极化信息提高雷达系统的检测性能和目标二维DOA的估计精度。

Multi-scale Sparse Polarization Sensitive Array and the DOA Estimation Algorithm

Combined with spatially-spread electromagnetic-vector-sensor(SS-EMVS) and sparse array, a new multi-scale sparse polarization sensitive array configuration composed of SS-EMVS is proposed in this paper. This array is placed along the y-axis, and the unit is a unique SS-EMVS. The whole array is composed of two subarrays with two different inter-element spacings which can be larger than a half-wavelength of the incident source, thus to form a multi-scale sparse polarization sensitive array to obtain the high accuracy estimations of direction of arrival (DOA). The proposed array combines the advantages of SS-EMVS that can reduce the mutual coupling of array elements and the advantages of sparse array that can expand the aperture of array. So that the estimation accuracy of target DOA is improved, the mutual coupling of array elements is reduced, and the robustness to noise is better. As for the algorithm, firstly, we perform the vector-cross-product algorithm to the SS-EMVS to obtain the low-accuracy but unambiguous direction cosine estimations. Secondly, we impose the spatial rotational invariance of the two subarrays to get the high-accuracy but cyclically ambiguous direction cosine estimations. Following this, a multiscale disambiguation algorithm is developed to obtain the high accuracy and unambiguous estimations of direction cosines, thus the elevation angles, azimuth angles of multiple sources. Simulation results verify the effectiveness of the proposed array and algorithm. This array can be used in some space-constrained applications, such as the sensor array installed on the aircraft, so as to give play to the characteristic of the electromagnetic vector sensor, which single antenna has multiple components. And it can also be combined with MIMO radar to improve the detection performance of radar system and the estimation accuracy of target 2-dimensional DOA with the addition of polarization information.