阵列天线散射条件下的互耦校正

Mutual Coupling Calibration of Array antenna in the Presence of Scattering

当阵列存在近场散射源时,互耦效应的分析和校正更加繁杂,这就导致了阵列互耦矩阵的参数化建模需要做进一步的扩展,使得互耦矩阵不再为方阵。然而现有的参数化互耦校正方法均假设互耦矩阵是一个具有特殊数学结构的方阵,对非方阵的互耦矩阵模型不适用。本文通过引入少量远离阵列且相互间隔较远的辅助阵元(互耦效应可以忽略)和方向未知的校正信源,提出了一种阵列天线散射条件下的互耦校正的参数估计算法。首先,推导了扩展后的非方阵互耦矩阵系数与方位依赖的幅相误差的等价关系;然后,对每次单源实验,得到校正源方位和各阵元方位依赖的幅相误差的联合估计,建立估计的幅相误差以非方阵互耦系数为参数的方程;最后,将多次单源校正得到的方程进行整合构建方程组,利用Tikhonov正则化方法求解不适定方程组实现互耦系数的有效估计,进而对阵列互耦进行校正。计算机仿真实验结果表明所提算法可以很好地解决阵列天线散射条件下的互耦校正问题,从而验证了算法的有效性。

Analysis and calibration of mutual coupling is more complicated in the presence of structure scattering caused by the platform or conducting plate located near the array.The parametric model of mutual coupling matrix should be extended,this makes the mutual coupling matrix is no longer a square matrix.Besides,the existing parametric array calibration methods for mutual coupling don＇ t work yet because they are proposed on the assumption that the mutual coupling matrix is a square matrix with a special structure. By using some instrumental sensors（the mutual coupling between them can be omitted） and auxiliary sources of unknown locations,an algorithm for array mutual coupling calibration in the presence of scattering is proposed.Firstly,the equal relation between the angularly dependent gain and phase distortion and the non-square mutual coupling matrix is presented.The non-square mutual coupling matrix can represent the effects of the mutual coupling between the array elements and the scattering simultaneously.Secondly,the angularly dependent gain and phase distortion of every array element and the DOA of the auxiliary source can be estimated every time with only one auxiliary source,the angularly dependent gain and phase distortion is a function of both the array steering vector and the non-square mutual coupling matrix.Lastly,repeat second procedure a few times,a few equations can be established.Combining the equations obtained together and solving equations with the help of Tikhonov Regularization,the non-square mutual coupling matrix can be computed effectively.Then the mutual coupling can be calibrated with the estimated non-square mutual coupling matrix.Computer simulation results demonstrate the proposed algorithm can achieve a favorable estimation of the non-square mutual coupling matrix for the purpose of array mutual coupling calibration in the presence of scattering.The effectiveness of the proposed algorithm is also demonstrated by the simulation results.