微波波导连接器无源互调的研究

发布时间：2018-11-04 10:00

【摘要】：近年来,随着通信行业的蓬勃发展,用户数量急剧增加,通信链路的大规模建设,使无源器件的使用十分普遍;与此同时,由无源器件非线性而产生的无源互调(Passive Intermodulation,PIM)干扰也日益严重。无源互调产物一旦落入接收机的频带内,将严重影响系统的通信质量,因此,如何降低无源互调干扰的问题越来越受到通信行业的关注,要降低通信系统中的无源互调干扰,对无源互调产生机理的研究非常必要,所以,对无源互调的研究具有一定的理论意义和实际意义。本文以矩形波导连接器为基础,对无源互调的产生机理进行分析并建立无源器件两级级联模型。无源互调的产生机理主要有:材料非线性和接触非线性,波导结处的接触非线性是无源互调产生的常见原因之一,主要的非线性机理为接触机理和半导体机理。接触机理认为,看似紧密接触的两个波导法兰,从微观上看,实际接触只发生在粗糙平面的少数微凸体上,流过波导结的电流向接触微凸体聚集时因为突然收缩而产生非线性,导致无源互调的产生。半导体机理主要来源于波导结处的金属-绝缘层-金属(Metal-Insulator-Metal,MIM)结构,因为空气氧化、沾污等原因在法兰表面形成一层纳米级的绝缘层,形成MIM结构。本文着重研究了半导体机理中的量子隧道效应和热电子发射效应,分析了两个效应中互调干扰的主要影响因素,及无源互调电流密度随各因素的变化趋势;讨论了在相同条件下,起主导作用的产生机理,对降低无源器件的互调干扰具有指导性意义。无源器件的大量使用,使一条通信链路中不止存在一个无源器件,针对目前无源器件级联的普遍现象,本文将无源器件简化为波导结,建立了两级级联模型。分析输入载波信号连续经过两个波导结后,无源互调功率的变化,考虑到用于连接两个波导结的传输线对输入载波信号的相位有影响,研究了无源互调功率随传输线相位长度的变化规律,输入载波信号的相位差与传输线相位长度的关系,从而可以有效的避开无源互调功率累加最大值,达到降低无源互调干扰的目的。
[Abstract]:In recent years, with the rapid development of the communication industry, the number of users has increased dramatically, and the large-scale construction of communication links has made the use of passive devices very common. At the same time, passive Intermodulation (Passive Intermodulation,PIM) interference caused by the nonlinearity of passive devices is becoming more and more serious. Once the passive Intermodulation product falls into the frequency band of the receiver, it will seriously affect the communication quality of the system. Therefore, the problem of how to reduce the passive Intermodulation interference is paid more and more attention by the communication industry, and the passive Intermodulation interference in the communication system should be reduced. It is necessary to study the mechanism of passive Intermodulation, so the study of passive Intermodulation is of theoretical and practical significance. Based on the rectangular waveguide connector, the generation mechanism of passive Intermodulation is analyzed and a two-stage cascade model of passive devices is established. The generation mechanism of passive intermodulation mainly includes material nonlinearity and contact nonlinearity. Contact nonlinearity at waveguide junction is one of the common reasons of passive intermodulation. The main nonlinear mechanism is contact mechanism and semiconductor mechanism. According to the contact mechanism, the two waveguide flanges which appear to be in close contact with each other, from the microscopic point of view, only occur on a few microprotrusions in rough planes. When the current flowing through the waveguide junction accumulates to the contact protrusions, it is nonlinear because of the sudden contraction of the contact flanges. Resulting in passive Intermodulation. The semiconductor mechanism mainly comes from the metal-insulator-metal (Metal-Insulator-Metal,MIM) structure at the junction of the waveguide. Because of air oxidation and contamination, a layer of nanoscale insulating layer is formed on the flange surface to form a MIM structure. In this paper, the quantum tunneling effect and the hot electron emission effect in semiconductor mechanism are studied. The main influencing factors of the intermodulation interference in the two effects and the variation trend of passive Intermodulation current density with each factor are analyzed. Under the same conditions, the dominant mechanism is discussed, which is of guiding significance to reduce the intermodulation interference of passive devices. With the extensive use of passive devices, there is more than one passive device in a communication link. In view of the common phenomenon of cascading passive devices at present, the passive device is simplified as a waveguide junction and a two-stage cascade model is established. After the input carrier signal passes through two waveguide junctions continuously, the change of passive intermodulation power is analyzed, considering that the transmission line used to connect the two waveguide junctions has an effect on the phase of the input carrier signal. The relationship between the phase difference of the input carrier signal and the phase length of the transmission line is studied in order to avoid the accumulative maximum of the passive intermodulation power effectively. The aim of reducing passive Intermodulation interference is achieved.
【学位授予单位】：华北电力大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TN814

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