【作者】 尚军平；

【导师】 傅德民；

【作者基本信息】 西安电子科技大学 ， 电磁场与微波技术， 2010， 博士

【摘要】 测量相控阵天线的辐射特性是一个复杂的技术课题。在现代相控阵雷达中,如何能快速准确地确定单元的幅相激励,并能诊断出单元的故障,对相控阵天线的研制和校验都具有重要的意义。近年来随着相控阵天线的应用越来越普及,对其测试技术也提出了新的要求。为适应这一要求,本文研究了一种快速测量及诊断相控阵天线的新方法即换相测量法。该方法的基本思想是在相控阵天线和测量探头均保持固定的情况下,测量相控阵天线不同配相状态下探头的接收信号幅相,然后用数学算法对实验数据进行处理即可确定任意配相状态下各通道激励的幅相,进而根据一次试验结果复原所有的方向图。该方法同时可进行单元故障鉴别,这是与其它测量法相比最大的优点。本文的主要成果包括以下几个方面:1.对在中等距离上用固定探头测量相控阵天线特性的基础理论进行了深入研究,建立了一个把相控阵天线在不同配相状态下,固定探头接收信号的幅相和相控阵天线各通道激励波的复振幅联系起来的数学表达式。对该测量方程的解的情况进行了分析,发现对于不同控制步骤得到的方程的系数矩阵的秩总不是满秩的。而且测量方程的求解过程中需要求其广义逆,这样造成求解通道激励特性的多值性。研究利用相控阵天线中相移器的一些先验信息和相移器的相移状态发生变化时它的幅度基本不变(或变化很小)的特点来消除多值性,评估其真实的激励,并可对通道故障进行判别和诊断。2.从该测量方法的数学模型可以看出,该测量方法主要是要确定各个辐射单元的阵中方向图和各通道的激励振幅。而且单元在阵中方向图不仅在各通道激励的求解过程中用到,在整个方向图的复原中也要用到,因此单元在阵中方向图的精度将直接影响到测试精度。本文对对称阵子为单元的相控阵天线的单元在阵中方向图进行研究,给出了满足一定精度要求的单元在阵中方向图的确定方法。3.为求解各个通道的激励,必须解相控阵天线不同配相时通道激励与探头接收信号建立的线性方程组。对单元数很多的大型相控阵天线不同测量控制步骤时的广义逆矩阵的求解仍然是一个未解的问题,但对一些特殊的矩阵形式,可以应用快速算法求解其逆矩阵。本文分别研究了按单元控制、以循环移位为基础的控制、以沃尔什函数为基础的控制、最佳配相控制制定的控制步骤,研究了它们各自的适应范围、测量误差及相应的快速算法。在理论研究的基础上,对以对称阵子为单元的相控阵天线模型的快速测量全部过程进行计算机仿真,仿真结果验证了该方法的正确性和高效性。4.研究发现换相测量法也存在着一些不足之处,特别是不管如何配相,控制步骤矩阵均为奇异矩阵。这样在解测量方程时,必须引入其他的先验知识。为了使换相测量法更实用,本文提出了改进的方法,即提出了换相测量法和编码矩阵方法相结合的方法,这样就不必引用其他先验知识,这不仅减少了测量次数还提高了测量的精度。5.在理论研究的基础上结合多年从事天线测量研究的经验,给出了相控阵天线快速测量系统的设备构成。对探头的最佳配置进行了讨论,并对该测量方法的设备误差、方法误差、数学算法误差、方向图的复原误差进行分析,提出了对系统和环境的要求。相控阵天线快速测量方法基于其自身的突出优点,能大大减少检测时间,对环境要求也低,因而具有很强的实用性。这使得它必将在未来相控阵天线的研制和生产中得以应用并发挥重大作用。更多还原

【Abstract】 Measurement of phased array antennas’radiation characteristics is a complex technical subject. In modern phased array antennas area, how to identify the amplitude and phase of element excitation rapidly and accurately and diagnose element faults are of great significance to the phased array antennas’manufacture and verification. Recently with the widespread application of phased array antennas, it has put forward new demands on measurement. To meet this requirement, a fast measurement method of phased array antennas called phase-shifted measurement method is introduced in this paper. The basic idea is that with the phased array antennas and probe both fixed, we measure the received signal’s amplitude and phase of phased array antenna corresponding to different phase states, then use mathematical algorithms to process the experiment data. Therefore we can determine channel excitation in any phase state, and further, we can recover all the patterns according to one of the measurement result. At the same time, element fault can be identified, which is the greatest virtue compared with other measurement methods. The main achievements are as follows.1. Through the intensive study of basic theories of using fixed probe to measure the characteristics of phased array antennas in the middle distance, a mathematical expression is established. The expression contacts the amplitude and phased of the fixed probe signal with the complex amplitude of each channel excitation wave of phased array antennas under condition of different match. Through the analysis of the solution to the expression, we find the rank of the expression’s coefficient matrix under different control steps is not full rank. And it is necessary to solve its generalized inverse matrix in the process of solving. It causes multi valuedness of the solution to channel excitation characteristics. Some priori information of the phase shifters of phased array antennas and the constant amplitude characteristics (or very tiny changes) as the phase state changes is utilized to eliminate multi valuedness of the solution, evaluate the real excitation and identify and diagnosis the channel faults.2. The main work of the measurement method is to determine the array pattern of each radiating element and the excitation amplitude of each channel. Since the array pattern of elements is used in the process of solving each channel excitation and the recovery of whole pattern. The accuracy of the array pattern of each element will directly affect the accuracy of measurement. The array pattern of elements in the phased array antennas made up of dipole antennas is studied in the paper. And a method to determine the array pattern of elements that meet certain accuracy is put forward.3. To obtain the excitation of each channel, the linear equations established by the excitation of channels and received probe signal of phased array antennas in different phase states must be solved. Solving the generalized inverse matrix remains an unanswered question in different measurement control steps of large phased array antennas composed of many elements. But for some special matrix form, we can use rapid algorithm to obtain its inverse matrix. The conforming rules of establish experimental steps is made based on the characteristics of phase-shift method. The control steps of the unit control, the circular phase-shift control and the Walsh function control, and the optimized phase-control is studied base on the principle of minimum error and measure numbers. The adaptation range, measurement error and corresponding fast algorithm are also studied. The whole process of the fast measurement of phased array antennas model made up of dipoles is simulated by computer on the basis of theory study. The results showed the correctness and efficiency of the method.4. The phase-shift measurement is characterized by its rapid recovery of the amplitude and phase of element excitation in different phase state. However, due to the singularity of the measurement equation, can be solved only by introducing additional equations. This cause much inconvenience and recovery error. Hence the combination of phase-shift measurement method and encoding matrix method as an improvement to made the measurement equation full rank. The method can reduce the measurement numbers and improve the measurement precision with any other priori knowledge.5. With the experience in antenna measurements research based on the theory study, the equipment composing of fast measurement system of phased array antennas is proposed. We have discussed the optimal configuration of probe, and analyzed the equipment error, the method error, mathematical algorithms error and the pattern’s recover error of this measurement method. Some requirement of system and environment is also proposed.Based on its advantage, the fast measurement method of phased array antennas can greatly reduce the test time. And the requirements of environmental are low. It will be used widely and play important role in the study and manufacture of phased array antennas in future.更多还原