阵列天线单元间的互耦分析与补偿技术

Abstract
Abstract
Antenna array as high-gain antenna has been widely used in various communication systems. However, the characteristics of antenna array changed fundamentally due to the mutual coupling between elements. That coupling is not negligible especially when the element spacing is small. Because of the effect of coupling, the distribution of array aperture, the input impedance and the radiation pattern were changed. It is necessary to analyze the mutual coupling in antenna array deeply and make some compensation, particularly in the development of high-performance antenna array such as low side-lobe antenna and ultra-low side-lobe antenna. That’s the reason why the analysis of the mutual coupling in antenna array has great significance and practical value. In this paper we use dipole array as an example to analyze mutual coupling in it and make certain compensation, with the purpose to illustrate the mutual coupling in slot antennas on waveguides based on the equivalence between dipole and slot antenna in their radiation pattern. Here we calculated the current distribution of a half-wave dipole antenna through the Matlab programming using the method of moments (MOM), and compared to the same result from the calculation of the simulation software FEKO which based on MOM to verify the correctness of the program, and then give the current distribution on each element in the linear dipole array with uniform element spacing by FEKO simulation, in this way to indicate the mutual coupling in antenna array. As the focus of this article, we analyze the mutual coupling in the dipole array which contains 104 elements and make certain of its mutual coupling compensation. By this way we illustrate the mutual coupling in a kind of irregular slot antennas on waveguides. Firstly we analyze the mutual coupling in the linear dipole array, and make certain of its mutual coupling compensation by adjusting the amplitude and phase of each element. Elements’ amplitude was weighted using Taylor incentive-weighted and their phase was adjusted by changing the length of each element according to the observation of each element’s resistance status after the simulation, so that they can achieve the minimum Voltage Standing Wave Ratio (VSWR). In this way the mutual coupling in the dipole array should compensated and its radiation performance improved; secondly we get to the analysis of the rectangular
西安电子科技大学 硕士学位论文 阵列天线单元间的互耦分析与补偿技术 姓名：席磊 申请学位级别：硕士 专业：电磁场与微波技术 指导教师：尹应增;马金平 20100101
摘要
摘
要Leabharlann 天线阵列作为高增益天线已被广泛应用于各种通信系统中。然而，在天线阵 列中常常因为单元间的互耦使得天线阵列的特性发生根本性的变化。特别当单元 间距较小的时候，耦合作用更是不可以忽略的。单元间互耦的存在，使阵列的口 径分布、输入阻抗和辐射方向图发生了改变。尤其是在研制低副瓣天线和超低副 瓣天线等高性能天线阵时，就需要对天线单元间的互耦进行深入的分析，并做出 必要的补偿。可见分析阵列单元之间的互耦影响具有很重要的意义和实用价值。 本文主要是以对称振子阵列为例来分析阵列单元之间的互耦影响，并对其互 耦做出一定的补偿，从而依据对称振子和缝隙天线的等效性来说明波导缝隙阵中 的互耦影响。文章通过 Matlab 编程用矩量法计算了半波振子天线上的电流分布， 并且和基于矩量法的仿真软件 FEKO 的计算的结果相比较， 验证了程序的正确性。 然后用 FEKO 仿真计算了均匀直线阵中各单元上的电流分布，说明了阵列天线中 阵元间的互耦影响。 为了说明一个不规则波导缝隙阵中的互耦影响，本文重点分析了一个相对应 的 104 元对称振子阵列单元之间的互耦影响，并对其互耦做出一定的补偿。文章 首先分析了均匀线阵的互耦影响，通过调节阵列单元的幅度与相位来对其互耦作 出一定的补偿。单元的幅度采用泰勒激励加权的方式，然后通过仿真来观察各个 单元的阻抗状况，以此对单元的长度进行相应的调节来改变其相位，使每个单元 的驻波比达到最小。这样我们就能对阵元之间的耦合做出一定的补偿，改善阵列 的性能；其次以均匀线阵为基础分析了包含整个波导缝隙阵轮廓的规则的矩形平 面阵。平面阵可以看成横向和纵向线阵的组合，所以我们只需采用和均匀线阵一 样的方法来调节各单元的幅度与相位，使各单元的驻波比达到最小；最后对于不 规则的对称振子阵列，去掉多余的单元之后，其余各单元间的耦合影响较之前会 发生很大的变化。由于阵列形式的特殊性，需要进一步调整阵列的激励幅度分布 及各单元的相位， 使单元驻波比最小， 从而对阵列单元间的互耦做出一定的补偿。 最终结果显示：对称振子阵列总增益为 24.5dB，因为对称振子阵列为双向辐 射， 所以对应单向辐射的波导缝隙阵增益应为 27.5dB。 阵列 E 面三个方向 （Phi=0， Phi=45，Phi=90）上的方向图副瓣电平均小于-17dB，满足增益不小于 27dB，副 瓣电平小于-16dB 的要求。各端口的驻波特性也得到了明显的改善。说明经过单 元的幅度与相位的调节，阵列单元间的耦合得到了一定的补偿，提高了阵列的性 能。 关键词：互耦补偿 矩量法 激励加权 相位调节 对称振子阵列
requirements that total gain>=27dB, side-lobe=<-16dB. Each element’s VSWR has also
improved significantly. It indicates that the mutual coupling in antenna array has a certain amount of compensation and the antenna array’s radiation performance improved. Key words: Mutual coupling compensation Phase adjustment Dipole array MOM Incentive-weighted
阵列天线单元间的互耦分析与补偿技术
planar array antenna containing the entire outline of the slot antennas on waveguides. Planar array is the combination of horizontal and vertical linear array antenna, we only need to use the same approach in linear array analyzed before to adjust the amplitude and phase of each element; finally for the irregular dipole array, the coupling has changed a lot after removing redundant elements. Because of the particularity of the dipole array form, we need to make further adjustment of each element’s amplitude and phase to achieve the minimum VSWR. The final result shows: The total gain of the array reaches 24.5dB. Because dipole array is two-way radiation, the gain of the corresponding one-way radiation slot antennas on waveguides shall be 27.5dB. The side-lobe of three directions (Phi=0, Phi=45, Phi=90) in E plane of the array pattern are all lower than -17dB, they meet the