微波暗室设计评估与验证方法的研究

发布时间：2018-04-05 15:36

本文选题：屏蔽效能　切入点：反射率电平　出处：《北京交通大学》2017年硕士论文

【摘要】：微波暗室利用屏蔽材料屏蔽外界电磁干扰,吸波材料抑制内部电磁多路径反射干扰,二者结合获得一个相对寂静的电磁测量环境。它能提供电平低而恒定的电磁环境,提高测量的精度和可靠性。在城市轨道交通中,无线通信射频设备具有传输频率范围宽(0.5GHz-6GHz)、传输方式多样性(定向天线、漏泄电缆、漏泄波导管)等特点,普通微波暗室无法满足城市轨道交通射频设备的测量需求。搭建一个专门用于测试城市轨道交通射频设备的微波暗室,减小无线电磁波干扰对测试结果的影响,对更准确的分析设备性能很有帮助。本文主要研究用于城市轨道交通射频设备测量的微波暗室的设计、评估和验证方法。具体研究内容如下:1)研究用于城市轨道交通射频设备测试的微波暗室设计方案。从传输方式、传输频段的角度分析了城市轨道交通射频设备的测量需求,定量计算了微波暗室设计需要的主要参数指标,为微波暗室的屏蔽材料和吸波材料的选取提供具体的参数,给出微波暗室的结构和测量系统的设计方案。2)研究微波暗室主要参数指标的评估方法和评估过程。分析了微波暗室屏蔽效能、静区反射率电平、交叉极化度、场幅度均匀性、多路径损耗五个主要性能指标对测量结果的影响,结合微波暗室的实际设计情况,确定具体的评估方法和评估过程,得到评估结果。与理论计算的结果进行对比,评估微波暗室的设计满足城市轨道交通射频设备测量需求。3)对用于城市轨道交通无线通信系统的八木天线、漏泄波导管进行测量,分析测量结果,验证微波暗室的测量系统性能。比较了微波暗室测量的天线方向图与标准天线方向图的最大接收电平、最大副瓣电平、3dB波宽等电参数误差。采用快速傅立叶变换(FFT)将天线近场测量结果转换成远场,比较与远场天线方向图间的3dB波宽误差。分析了漏泄波导管多次测量结果误差。验证了微波暗室测量系统的可用性和稳定性。结果表明,通过对微波暗室的多项性能指标的评估,微波暗室的测量环境满足设计过程中提出的各项性能指标要求。定向天线测量结果与标准天线方向图对比,3dB波宽误差在±1°左右,接收端最大电平、最大副瓣电平误差在±3dB之内,标准喇叭天线近场测量结果转换成远场,对比远场天线方向图,3dB波宽的误差角度在±4°范围内,满足工程上的测量误差需求。漏泄波导管多次测量结果误差在土 1dB之间,满足微波暗室测量稳定性需求。微波暗室的设计达到了城市轨道交通射频设备性能测试的要求。
[Abstract]:The microwave darkroom uses shielding material to shield the external electromagnetic interference and absorbing material to suppress the internal electromagnetic multipath reflection interference. The two methods combine to obtain a relatively quiet electromagnetic measurement environment.It can provide a low-level and constant electromagnetic environment and improve the accuracy and reliability of the measurement.In urban rail transit, radio frequency equipment for wireless communication has the characteristics of wide transmission frequency range of 0.5GHz to 6GHz, diversity of transmission modes (directional antenna, leaky cable, leaky waveguide tube), etc.Ordinary microwave darkroom can not meet the measurement requirements of urban rail transit RF equipment.A microwave darkroom specially used to test the RF equipment of urban rail transit is built to reduce the influence of the radio electromagnetic wave interference on the test results. It is helpful to analyze the performance of the equipment more accurately.This paper mainly studies the design, evaluation and verification method of microwave darkroom used for measuring RF equipment of urban rail transit.The main contents are as follows: (1) the design of microwave darkroom for testing RF equipment of urban rail transit is studied.From the point of view of transmission mode and transmission frequency band, the measurement requirements of radio frequency equipment for urban rail transit are analyzed, and the main parameters needed for the design of microwave anechoic chamber are calculated quantitatively.This paper provides specific parameters for the selection of shielding materials and absorbing materials for microwave anechoic chamber. The structure of microwave darkroom and the design scheme of measuring system are given. 2) the evaluation method and evaluation process of the main parameters of microwave anechoic chamber are studied.The effects of five main performance indexes, such as shielding efficiency, static area reflectivity level, cross-polarization, field amplitude uniformity and multipath loss, on the measurement results are analyzed.Determine the specific evaluation methods and evaluation process, and obtain the evaluation results.Compared with the theoretical calculation results, the design of microwave darkroom is evaluated to meet the measurement requirements of radio frequency equipment of urban rail transit. 3) the Yagi antenna and leakage waveguide tube used in urban rail transit wireless communication system are measured, and the measurement results are analyzed.Verify the measurement system performance of microwave darkroom.The maximum receiving level and the maximum sidelobe level of the antenna pattern measured in the microwave anechoic chamber are compared with those of the standard antenna pattern.The near field measurement results of antenna are converted into far field by fast Fourier transform (FFT), and the 3dB wave width error between the antenna pattern and the far field antenna pattern is compared.The error of multiple measurements of leaky waveguide is analyzed.The availability and stability of the microwave anechoic measurement system are verified.The results show that the measurement environment of the microwave darkroom can meet the requirements of the design process through the evaluation of several performance indexes of the microwave anechoic chamber.Compared with the standard antenna pattern, the measurement result of directional antenna has a 3dB wave width error of 卤1 掳, the maximum level at the receiver end and the maximum sidelobe level error within 卤3dB. The near-field measurement results of the standard horn antenna are converted to the far field.Compared with the far-field antenna pattern, the error angle of 3dB wave width is in the range of 卤4 掳, which meets the requirement of engineering measurement error.The error of multiple measurement results of leaky waveguide is between soil 1dB, which meets the requirement of stability measurement in microwave anechoic chamber.The design of microwave darkroom meets the requirements of RF equipment performance test for urban rail transit.
【学位授予单位】：北京交通大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TN03;TN820

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