【作者】 王伟；

【导师】 段宝岩；

【作者基本信息】 西安电子科技大学 ， 机械制造及其自动化， 2011， 博士

【摘要】 在国家重大基础科研(国防973)项目的支持下,基于前人的工作,本文主要就机械结构因素对反射面天线电性能的影响机理以及基于影响机理的面板调整方法进行了研究。完成的主要工作和取得的成果如下:1.根据分块反射面天线的结构特点,推导出了面板偏移量与口面相位误差的转换矩阵。基于此误差转换矩阵,分析了面板位置误差对分块反射面天线电性能的影响机理。建立了面板加工误差与副面位置误差对天线电性能的影响关系模型。最后,在3.7米口径Ku频段反射面天线上对影响机理模型进行了实验验证。选择了6米口径Ku频段反射面天线上进行了仿真实验,给出了有用的结果数据和曲线。2.基于对天线结构受力情况的精确分析,得出了结构位移随天线仰角的变化关系。应用最小二乘法计算了变形反射面的最佳吻合抛物面,把表面节点相对于最佳吻合面的均方根误差表示为天线仰角的函数。应用Ruze公式得到变形后反射面天线效率。把天线在各个仰角或者各个工作仰角区段出现的概率作为加权因子,以天线的增益损失最小为目标,建立了天线反射面面板最佳安装调整角的优化模型。3.分析了大型反射面天线面板安装调整的特点,选择最佳吻合面作为调整目标面,给出了一种有效的面板调整方式以及相应的最佳调整量的计算方法。在此基础上研制了天线面板安装测调软件。对某6米口径Ku频段反射面天线进行了仿真分析,优化计算出了面板调整量,并对调整效果进行了分析。4.为提高天线面板调整效率,以反射面天线的远区电场方向图为研究对象,应用物理光学法建立了表面节点位移与远区电场的关系模型,将面板调整量与远区电场联系起来,从而实现了由远区电场方向图反推天线反射面的面板调整量。对工程案例进行了分析,给出了相关数据和曲线。讨论了此方法的适用范围,为天线反射面板的精确调整提供了指导。5.为抵消赋形曲面天线在各个工作仰角的部分变形,给出了一种通过调整副面位置来实时补偿的方法。首先应用标准抛物线对天线理论母线进行分段拟合,得到一组标准抛物环面。用此组抛物环面去吻合天线在各个仰角的变形主面,同时保证各抛物环面的焦点落在设计理论面的焦线段上,得到一组主面吻合参数。根据主副面之间的匹配关系,计算出天线在各个仰角的副面调整参数。在天线实际工作过程中,计算机控制读取副面的调整参数,驱动副面移动到最佳位置,方可实现对主面变形的实时补偿。更多还原

【Abstract】 This work was supported by a grant from the National Program on Key Basic Research Project (973 Program). On the basis of the predecessor work, this thesis is mainly concerned with the influence mechanism of mechanical factors on the electrical performance of reflector antenna and its application in surface panel adjustment. The main research work can be described as follows.1. In accordance with the characteristic that the large parabolic reflector antenna surface are divided into panels, the ETM (Error Transformation Matrix) between panel positional errors and aperture phase errors is derived. Based on the ETM, the influence mechanism of panel positional error on the electrical performance of reflector antenna is analyzed. And the effect model of panel fabrication error and sub-reflector positional error on the electrical performance of reflector antenna is given. Then, an experiment is implemented on a 3.7m reflector antenna with 12 panels which verified the method mentioned above. At last, a 6m reflector antenna is simulated and some useful data and figures are obtained.2. Based on the precise analysis of antenna structure, a gravity deformation model was derived by superposition which described the main reflector distortion over the entire range of elevation angles. The corresponding formulae were also deduced based on the analysis of antenna structure. The BFP (Best-Fit Paraboloid) of the deformed reflector surface is calculated by the LSM (Least Squares Method). In accordance with convention, the distortion RMS (Root Mean Square) of the deformed reflector surface was considered with respect to the BFP. The aperture efficiency and gain loss is calculated using Ruze formula. An optimization method was presented to calculate the best rigging angle for reflector surface accuracy. To verify the present equations, a finite element model of 12m parabolic antenna structure was created and input to the ANSYS program for numerical simulation.3. After the analysis of the characteristic of panel adjustment for large segmented reflector antenna, the BFP is chosen as an objective surface shape. Then, an efficient method of panel setting is given, which can be used to optimize the quantity of panel adjustment. Based on the theoretical derivation, a software platform for surface measurement and panel adjustment of reflector antenna is developed. The simulation on a 6m parabolic reflector antenna with Ku band is done and the panel adjustment quantity is calculated. At last, the efficiency of the method mentioned in the thesis is discussed. The numerical simulations showed that the results may be applied to antennas with realistic panel schemes, for prediction of their electrical performance and surface adjustment.4. To improve the efficiency of panel adjustment of large segmented reflector antenna, a method for determination of panel adjustment quantity from far field pattern is presented. Using the method of Physical Optics (PO), the relationship between the far field value and the node displacement is derived. Then the panel adjustment vector is related to far field pattern with linear equations. Singular Value Decomposition (SVD) is used to find out a vector of panel adjustment quantity, which will be used for quick adjusting. An experiment is implemented on a 3.7m reflector antenna with 12 panels and some useful data and figures are obtained. The applicable range of the proposed method is also discussed, and the results are going to be useful guide for panel adjusting of large reflector antenna efficiently and precisely.5. On the degradation of electrical performance due to the main reflector deformation of large shaped Cassegrain antennas, a method for compensation by moving sub-reflector is presented. A group of best-fit paraboloids are found by least-square fitting the theoretical discrete data. The group of paraboloids is used to fit the deformed main reflector, with the constraint of all these focuses being in line. The best-fit parameters are optimized and the adjustments of sub-reflector are derived with the ratio of main reflector and sub-reflector. The adjustments at various attitudes are saved in a look-up table to real-time compensate for main reflector deformation. From the simulation testing on a 65m reflector antenna, satisfactory results are obtained and will be used in practice.更多还原