射频连接器无源互调机理研究与建模

Radio Frequency (RF) connectors are extensively used in communication systems to transmit signals between different circuit modules. It is generally known that the connectors will be degraded by the effect of environmental factors such as temperature, humidity, vibration, atmosphere corrosion and so on. Therefore, a serious passive intermodulation (PIM) interference will be induced by the nonlinear effect of RF connectors, especially in the high-power and multicarrier situation. These phenomena have received a lot of attentions in both academy and industrial. In this project, the generation mechanism and modeling of the passive intermodulation in RF connectors will be studied. The main contents include three parts as follows. First, the generation mechanism of PIM will be modeled based on the electrical contacts and material properties of connectors. Second, an equivalent circuit model of the degraded contact surface will be developed to investigate the effect of degraded connectors with different pollution level on the high frequency electric performance. And then, based on the high frequency impedance model, a series of accelerated tests considering different environmental stresses will be designed to study the influence of the degradation level of connectors on the PIM performance. Finally, by comparing the PIM characteristic models of two-tone signal in different wireless communication frequency bands, a novel method of modeling and predicting the PIM of broadband signal will be designed. Thus, the effect of analog modulation and digital modulation on the PIM will be analyzed and modeled. This research results will be of scientific significance for designing connector with low PIM interference, developing testing standards, improving connector reliability, improving quality of communication, as well as developing electrical contact theory in high frequency.

射频连接器是通信系统中大量存在的重要接口元件，随着环境因素如温湿度、振动、大气腐蚀等的影响，在大功率和多载波情况下，其非线性效应产生的无源互调直接影响整个系统的通信质量，该问题受到学术界和工业界的高度关注。本项目研究射频连接器无源互调产生的机理与建模。主要内容包括：基于连接器电接触表面和电接触材料特性，对无源互调产生机理进行建模；建立退化连接器的接触表面等效模型，分析连接器在不同退化程度下对高频电参数的影响，针对不同环境应力，设计加速试验，研究连接器退化程度对互调产物功率的影响机理；研究连接器通过不同无线通信频段的双音信号互调特征模型，设计宽带信号无源互调仿真与实验方案，研究模拟调制和数字调制信号互调特征模型。本项目研究对于降低互调干扰的连接器设计与工程应用、射频连接器检测标准的制定、提高连接器可靠性、提高通信系统可靠性具有重要的理论和实际意义，对于发展高频电接触理论具有重要的科学意义。

本项目“射频连接器无源互调机理研究与建模”针对射频连接器中复杂的无源互调形成机理和射频连接器中无源互调干扰抑制需求，在连接器结构设计、无源互调模型搭建、接触面等效电路模型构建，以及无源互调测试等方面取得了创新性成果。主要研究成果包括：（1）射频连接器无源互调产生机理与建模。基于连接器的电接触表面和电接触材料特性，分别对接触以及材料引起的无源互调进行理论建模；（2）环境引起的连接器退化对无源互调的影响研究。针对不同环境应力，设计加速试验，研究连接器退化程度对互调产物功率的影响规律；（3）连接器无源互调对不同传输信号影响机理与建模。通过电路仿真研究宽带信号无源互调的行为特点，建立模拟调制和数字调制信号的互调特征模型；（4）系统无源互调特征建模与应用研究。针对系统中存在的多互调源，进行整个系统的无源互调干扰建模并给出无源互调抑制方案；（5）高频高速电连接的失效机理研究与建模。将电连接失效机理研究扩展到高频高速，对高频高速电连接中存在的退化、失效问题进行研究与建模。本项目创新成果为低互调射频连接器设计与工程应用提供了建模思路、理论支持和技术参考，解决通信链路中连接器端的无源互调信号干扰问题，从而提高通信系统整体的可靠性。