基于数字示波器的环境电磁波测试方法研究

【作者】 李群岭；

【导师】 王拓； 王建忠；

【作者基本信息】 中国工程物理研究院 ， 辐射防护及环境保护， 2011， 硕士

【摘要】 在国防高功率微波武器研究中,所产生的高能微波脉冲具有功率高,脉宽窄,占空比低等特点,由于其脉冲峰值很高,因此会对人体和设备造成严重危害。目前,场强测量主要集中在频域范围内,没有时域场强标准,而现有的频域方法无法完成对该类脉冲信号的测量,超低占空比的瞬态窄脉冲电磁波测量是我国环境电磁波测量研究和评价中的一个空白。本论文从超低占空比的窄脉冲环境电磁波测量和环境评价的需求出发,分析了现有标准对这类信号测量和评价时存在的不足,设计并实现了一套基于数字示波器的时域场强测量系统,主要用于测量环境中距离辐射源在不同距离上瞬态脉冲信号的电场强度,并利用现行有效的标准作为判定依据,做出是否对人体造成危害的判断。在对该系统进行理论分析和实验验证中,以连续波为激励信号,与现行标准规定的非选频式宽带辐射测量仪器(PMM8053B电磁辐射分析仪)和选频式辐射测量仪器(ESI40测量接收机)测量结果比较,证明基于数字示波器的测量系统测量结果与这两套系统有很好的一致性。完成了窗函数对傅里叶变换的影响分析,并对宽带信号的复合场强利用不同算法完成数值模拟,研究出了一种适合计算调制脉冲信号复合场强的计算方法：峰值算术和法。在分析宽带信号中各分频信号功率与总信号功率的关系时,得出宽带信号总电压为各分频信号电压线性和,与仿真结果一致；并且数字示波器测量系统不受占空比的影响,其实验结果与仿真结果取得了较好的一致性,比现行标准规定的两套测量系统更加适用于调制脉冲信号复合场强测量。另外,本文还对该系统测量电场强度结果的不确定度进行了评定,其扩展不确定度为2.8 dB。在实验过程中用到了一些环境电磁波测量和电磁辐射防护的相关标准,随着实验的深入发现了这些国标中在一些关键内容上含义模糊,而且不同标准之间存在内容不统一的现象,对这些问题提出一些改进的观点和建议,对复合场强的计算、脉冲场强限值、远近场等内容进行了较为详细的讨论。希望能为以后的标准修订工作提供帮助。更多还原

【Abstract】 In the defense industry, high power microwave weapons (HPW) can emit high-energy pulse, which has the characteristic of high power, narrow pulse and low duty cycle, by the antennas. Its high peaks will harm human and damage equipment seriously. At present, the measurements of electromagnetic field strength are mainly concentrated in frequency domain range, without time domain standards. The frequency domain method of standard cannot measure this kind of pulse signal. It is a blind spot to measure and evaluate ultra-low duty cycle transient pulse in our country.This paper is for the environment electromagnetic measurement and evaluation demands of the narrow and ultra-low duty cycle pulses and the limitation of this kind of signal measurement and evaluation through present standards is discussed. A set requirement of time domain environment electromagnetic test system is designed based on digital oscilloscope to the need of test narrow width and low duty cycle pulse. This system is mainly used for test different distance environment electric intensity of pulse signal and use the prevailing standards to judge whether it will harm to human. The continuous wave is excitation signal in the system theoretical analysis and experimental verification, by the current standards of the frequency selective type broadband radiation test instruments (PMM8053B electromagnetic radiation analyzer) and frequency selective radiometric (ESI40 EMI Test Receiver), proofing the measurement system based on digital oscilloscopes measurement results and other two systems’good uniformity. The impact analysis is completed from window function to FFT. Peak plus method is developed to suit for calculating modulation pulse signal by numerical simulation of the calculation method of comprehensive intensity of field.When analyes the relationship between total power and each frequency power, the line relationship between broadband signals and each frequency of voltage is discovered, and the duty cycle has no influence on the digital oscilloscopes measurement system,which are consisted with simulation results.so the digital oscilloscope measurement system is more suitable to modulate pulse signal comprehensive intensity of field measurements than other two systems.Furthermore, this paper introduces the expanded uncertainty of the system in measuring electromagnetic intensity of field is 2.8 dB.When use the related standards about environmental electromagnetic wave measurement and radiation protection, there are some fuzzy key contents and incoherency between those standards. Comprehensive intensity of field calculation, pulse intensity of field and near and far field are also discussed in detail. Some suggestions were put forward to expecting to provide help in future standards recession.更多还原