微波频段无源互调干扰研究

发布时间：2018-01-20 10:37

本文关键词： 微波通信高功率无源互调非线性失真测试技术　出处：《哈尔滨工业大学》2014年硕士论文　论文类型：学位论文

【摘要】：近几年，随着高功率、大容量、高灵敏度通信系统的发展和应用，无源互调（Passive Intermodulation，简称PIM）问题作为一个技术难点而越来越得到人们的重视。无源互调本身是由无源器件的弱非线性特性引起的，，例如非线性电路特性和非线性电磁特性。在小信号条件下，无源非线性失真是可以忽略的。但是，在高功率条件下，原本可以忽略的无源弱非线性失真变得异常突出。通常，有源器件非线性产生的失真信号可以通过滤波技术消除在允许的范围内。然而，无源互调失真产物紧邻工作频率的特点使其可以落入工作频带内。这成为了消除技术的难点所在。此外，无源互调往往还会出现在滤波器后面，因而是难以消除的。严重的失真不仅会降低接收机灵敏度、影响正常通信质量，还会使整个系统恶化，甚至发生故障。无源互调产生的机理是错综复杂的，往往是多种物理过程综合作用的结果，因而人们往往凭经验和行为模型来描述其背后的原因。本文首先从无源非线性机理出发，阐述引起无源非线性的主要物理原因，数学模型以及分析方法。其次，以电热效应为背景，研究了印刷电路板上微带线无源互调产生的机理。从物理机理和现象学两个角度，分别利用两种方程对微带线无源互调产生、分布以及特点规律进行研究。最后，利用现有仪器搭建了无源互调测试系统。当输入信号的功率为27dBm时，我们观察到了比较明显的三阶互调信号。制作了多阻抗共面微带板，对多个微带板进行了测试，重点研究了不同阻抗匹配情况、微带线线长度与三阶互调信号产生的关系，并基于电压驻波原理，提出了一种短路线测量方法。实验测试证明，短路驻波能将电压波腹点处的互调信号放大17dB以上。这将大大提高系统的测量动态范围，实现在相对较小的输入功率下测试到相同大小的互调信号，大幅度降低互调测试对于输入功率的要求。
[Abstract]:In recent years, with the development and application of high power, large capacity and high sensitivity communication systems, passive Intermodulation has been adjusted passively. As a technical difficulty, the problem of PIMs has been paid more and more attention. Passive Intermodulation is caused by the weak nonlinearity of passive devices. For example, nonlinear circuit characteristics and nonlinear electromagnetic characteristics. In small signal conditions, passive nonlinear distortion can be ignored. However, under high power conditions. The passive weak nonlinear distortion which can be neglected has become very prominent. Usually, the distortion signal generated by the nonlinear of active devices can be eliminated within the allowable range by filtering technique. The passive Intermodulation distortion products can fall into the working frequency band, which is the difficulty of the elimination technology. In addition, passive Intermodulation often appears behind the filter. Therefore, it is difficult to eliminate. Serious distortion will not only reduce the receiver sensitivity, affect the normal communication quality, but also make the whole system deteriorate or even fail. The mechanism of passive Intermodulation is complicated. It is often the result of a variety of physical processes, so people often use experience and behavior model to describe the reasons behind it. In this paper, the main physical reasons, mathematical models and analysis methods of the passive nonlinear are first expounded from the passive nonlinear mechanism. Secondly, the electrothermal effect is taken as the background. In this paper, the mechanism of passive intermodulation of microstrip lines on printed circuit board is studied. From the point of view of physical mechanism and phenomenology, two kinds of equations are used to produce passive intermodulation of microstrip lines. Finally, the passive intermodulation test system is built using the existing instruments. When the power of the input signal is 27dBm. We have observed the obvious third order intermodulation signal. We have made multi-impedance coplanar microstrip plate and tested several microstrip plates with emphasis on different impedance matching. The relationship between the length of the microstrip line and the generation of the third order intermodulation signal, and based on the principle of voltage standing wave, a short line measurement method is proposed. The short circuit standing wave can amplify the intermodulation signal at the voltage wave belly point by more than 17dB. This will greatly improve the dynamic range of the system and realize the measurement of the same size intermodulation signal at relatively small input power. The requirement of input power for Intermodulation testing is greatly reduced.
【学位授予单位】：哈尔滨工业大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TN972

【参考文献】