自适应阵列天线互耦校准方法的研究

发布时间：2018-10-10 13:26

【摘要】：阵列天线广泛应用于雷达、通信、导航、电子对抗等众多领域。然而,随着小型化及宽带化需求的增加,互耦对阵列性能的影响不容忽略。由于互耦的影响,可能导致雷达分辨力降低、测向误差增大、干扰零陷抬高以及波束指向偏离等不良后果。为了提高阵列天线的性能并适应更广泛的应用,研究互耦校准方法具有重要意义。本文针对以上研究背景开展了阵列天线互耦校准方法的研究。本文详细介绍了阵列互耦产生的机理及分析方法,总结了已有方法的优缺点,提出了新的互耦校准方法,并在此基础上提出了宽带阵列互耦校准方法。论文的主要工作包括以下几个方面:1.在分析了互耦机理及已有互耦校准方法的基础上,从电磁分析的角度提出了新的互耦校准方法——单元方向图重建法。该方法利用单元孤立方向图和单元阵中方向图的差异,建立互耦矩阵的求解方程,并采用最小二乘法实现互耦校准矩阵的求解。在此基础上,进一步推导出阵列单元形式一致的简化单元方向图重建法表达式。2.针对全向天线及定向天线阵列开展了互耦校准的研究,将提出的方法应用于阵列天线的互耦校准。实现了对不同阵列单元、不同阵列形式的互耦校准研究。具体研究了全向、定向及线极化、圆极化等天线单元形式。研究的阵列形式包括线阵、圆阵及共形阵等。并将单元方向图重建法运用到一维和二维DOA估计算法中,实现了对阵列接收信号的校准,仿真验证了所提出的互耦校准方法的有效性。3.在单元方向图重建法的基础上,结合自校正方法的思想,提出了根据来波信号方向自适应的选择拟合区域对信号进行互耦校准的方法。该方法与MUSIC算法相结合,通过交替迭代实现了宽角度DOA估计。在此基础上,将提出的方法用于一维线阵、二维L形阵列的互耦校准,实现了一维和二维DOA的精确估计。4.提出了采用插值法实现宽带阵列互耦校准的方法。针对宽带信号耦合矩阵参数与频率的关系曲线,基于单元方向图重建法,提出采用保形分段Hermite插值法实现宽带互耦校准。仿真设计了宽带对称振子并用其构成八元均匀圆阵,DOA效果验证了所提出方法的有效性。5.研究了互耦对MIMO系统信道容量的影响。利用加载枝节和改变地板缝隙的方法分别设计了两款小型化多频缝隙天线,并用其构成MIMO阵列。利用单元方向图重建法实现对MIMO阵列天线互耦矩阵的求解,针对瑞利衰落信道开展互耦对信道容量影响的研究。6.搭建了系统实验平台,利用DOA估计实验完成对单元方向图重建法的验证。该实验平台包括天线阵列、射频模块和数字信号处理模块等。针对单极子天线阵列及微带天线阵列,进行DOA估计实验,分析对比了不同情况下的DOA估计结果,验证了单元方向图重建法的有效性和实用性。
[Abstract]:Array antennas are widely used in radar, communication, navigation, electronic countermeasures and many other fields. However, with the increasing demand for miniaturization and broadband, the effect of mutual coupling on array performance should not be ignored. Due to the influence of mutual coupling, the radar resolution may be reduced, the direction finding error will increase, the interference will be raised and the beam-pointing will deviate. In order to improve the performance of array antennas and adapt to more extensive applications, it is of great significance to study mutual coupling calibration methods. In this paper, the mutual coupling calibration method of array antenna is studied in view of the above research background. In this paper, the mechanism and analysis method of array mutual coupling are introduced in detail, the advantages and disadvantages of existing methods are summarized, a new mutual coupling calibration method is proposed, and a wideband array mutual coupling calibration method is proposed. The main work includes the following aspects: 1. Based on the analysis of the mutual coupling mechanism and the existing mutual coupling calibration methods, a new mutual coupling calibration method, the unit pattern reconstruction method, is proposed from the point of view of electromagnetic analysis. In this method, the solution equations of the mutual coupling matrix are established by using the difference between the isolated pattern of the element and the square diagram of the element array, and the solution of the mutual coupling calibration matrix is realized by using the least square method. On this basis, the expression of simplified element pattern reconstruction method with uniform array element form is derived. 2. The mutual coupling calibration of omnidirectional antenna and directional antenna array is studied, and the proposed method is applied to the mutual coupling calibration of array antenna. The mutual coupling calibration of different array elements and different array forms is realized. The antenna elements such as omnidirectional, directional and linear polarization and circular polarization are studied in detail. The array forms are linear array, circular array and conformal array. The method of cell pattern reconstruction is applied to one and two dimensional DOA estimation algorithm to realize the calibration of array received signals. The simulation results show that the proposed method is effective. Based on the method of unit pattern reconstruction and the idea of self-tuning method, a mutual coupling calibration method is proposed based on the adaptive selection of fitting region according to the direction of incoming signal. The method is combined with the MUSIC algorithm and the wide angle DOA estimation is realized by alternating iteration. On this basis, the proposed method is applied to the mutual coupling calibration of one dimensional linear array and two dimensional L shape array, and the accurate estimation of one and two dimensional DOA is realized. A method of wideband array mutual coupling calibration using interpolation method is proposed. Aiming at the relation curve between the parameters of wideband signal coupling matrix and frequency, based on the method of cell pattern reconstruction, a new method of wideband mutual coupling calibration based on conformal piecewise Hermite interpolation is proposed. A wide-band symmetric oscillator is designed and used to form an octa-element uniform circular array. The DOA effect verifies the effectiveness of the proposed method. The influence of mutual coupling on the channel capacity of MIMO system is studied. Two miniaturized multi-frequency slot antennas are designed by means of loading branches and changing floor slits, respectively, and MIMO arrays are constructed with them. The method of cell pattern reconstruction is used to solve the mutual coupling matrix of MIMO array antenna. The influence of mutual coupling on the capacity of Rayleigh fading channel is studied. The system experiment platform is built and the DOA estimation experiment is used to verify the method of unit pattern reconstruction. The experimental platform includes antenna array, RF module and digital signal processing module. The experiment of DOA estimation for monopole antenna array and microstrip antenna array is carried out. The results of DOA estimation under different conditions are analyzed and compared. The validity and practicability of the method are verified.
【学位授予单位】：西安电子科技大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：TN820

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