【作者】 祝忠明；

【导师】 王绪本；

【作者基本信息】 成都理工大学 ， 地球探测与信息技术， 2017， 博士

【摘要】 近年来,自然或人为灾害等各类突发事件的潜在危险与日俱增,一旦发生,将会造成人民生命财产的巨大损失。国内外多次大震后抢救生命的事实证明:对压埋人员抢救愈及时,救生、救活的可能性愈大。因此,为确保在紧急救援中用最短的时间找到被困人员,采用各种方法和手段来获取生命信号并进行分析,从而判定生命体的存在与否,存活与否。开展先进的生命救助探测与定位方法研究,具有十分重要的意义。本文提出用超宽带(UWB)电磁法进行地下目标体探测或穿墙探测的方法。即使用电磁脉冲进行生命救助探测与定位方法研究,它体现了瞬态电磁场理论、窄脉冲信号发射技术、高速采样技术、UWB天线和信号处理技术等多学科领域的研究成果,具有模拟精确、无损伤、分辨率高和探测深度大(或穿透能力强)等优点。首先分析了UWB电磁脉冲信号的产生,讨论了超宽带信号的辐射和时域测量技术,重点讨论了冲击脉冲超宽带雷达的探测原理,同时分析了超宽带雷达对人体目标的测量方法及原理。针对探测中分辨率和探测深度双提高要求,研究了自由空间中的电磁波辐射及衰减特性,研究分析超宽带电磁波场的特征。通过对数学物理方程的计算和计算机模拟,研究了超宽带电磁脉冲的产生机理和传播特性,分析了一般时空源分布近远场超宽带电磁辐射特点和规律,完成超宽频带电磁脉冲的场分析、散射波特性分析。从电磁波对介质的穿透现象出发,分析了电磁波穿透介质的机理,并对超宽带电磁波在有耗介质中的波场特征及衰减特性进行了研究,最后对电磁波传播参数与介质电性质的关系进行了分析。在地下有耗介质里的传播特征、能量分布特征、分辨率与探测深度、发射电磁脉冲的时宽或频宽与回波中有效信息量的关系等基础理论问题;开展了用超宽带电磁脉冲对地下介质的高分辨率探测研究,使用有限面积的口径天线,馈入大功率、窄脉冲信号,以同时提高探测深度和分辨率。用高阶时域有限差分(FDTD)法对任意复杂地下介质模型和穿墙生命探测的理论模型进行数值模拟,揭示了窄脉冲电磁波在复杂介质里的传播规律和目标的脉冲响应特征;对超宽带信号源特征、超宽带电磁波的FDTD方法及吸收边界处理方法、进行了超宽带电磁波在地下介质中的波场模拟,根据模拟结果,分析了超宽带在地下介质的传播特征、分辨率、探测深度和能流密度分布特征。实现了任意复杂介质的UWB电磁波场模拟。直观显示了UWB电磁波在几种典型地下探测模型和地面上穿墙探测人体模型里的传播过程,解释了电磁波与有耗地下介质的相互作用机理;分析了天线参数和地电参数对辐射场性能的影响,进而讨论了UWB电磁法的分辨率和探测深度等问题,为UWB电磁法的解释和走向实际提供理论指导。更多还原

【Abstract】 Recently,natural or man-made disasters and other types of potentially dangerous incidents are increasing and would cause great loss of people’s lives and property,once occurred.It proves that the more timely to rescue the buried,the more possible to save the life after many life-saving home and abroad.Therefore,it is of great significance studying on the advanced detection and location method of life rescue,and using a variety of ways and means to obtain and analyze the signals,in order to determine the existence of life and survival.The method of underground target detection and through-wall detection for life rescue detection and location using ultra-wideband(UWB)electromagnetic pulse has been studied,which is the integration of multidisciplinary research including transient electromagnetic field theory,narrow pulse signal transmission technology,High-Speed sampling technology,UWB antenna technology,signal processing technology,and so on.There are such many advantages with it as non-invasive,high resolution and large depth(strong penetrability),etc.First of all,generations of UWB electromagnetic pulse signals are analyzed.And then,radiation and time-domain measurement technology of UWB signal has been discussed focusing on the detection and measurement methods of shock pulse UWB radar and principles of UWB radar when taking into account the target of the human body.Radiation and attenuation characteristics of UWB electromagnetic field in free space has been studied through analytic calculations and numerical simulations of mathematical physics equations.More than that,generation mechanism and propagation characteristics of UWB electromagnetic pulse had been investigated and the near and far field characteristics and laws of UWB radiation had been analyzed for improving detection resolution and probing depth.Mechanism of high resolution detection of UWB EMP has been studied.Characteristics of wave field,attenuation,energy distribution in underground lossy medium,and the relationship between the electromagnetic wave propagation parameters and medium electrical properties are all analyzed.Detection parameters of the detection depth,resolution,bandwidth and pulse width of electromagnetic wave,and the relationship between the amount of information of echo wave and them are decided.Further,the method of aperture antennas with finite area,feeding high power,narrow pulse signal is investigated to improve the detecting depth and resolution at the same time.The models of arbitrary complex underground medium and through-wall surveillance are set and simulated Using high order finite difference time domain(FDTD)method with absorbing boundary condition of CPML to investigate how the electromagnetic wave transmits in lossy dielectric,the characters of UWB pulse and it’s response to target,and show the detection depth,transmission character,resolution,and the distribution characteristic of energy flow density.More than that,several simulations of typical underground and through-wall models are carried out to show spreading process of UWB electromagnetic wave in complex medium,explain the mechanism of interaction between electromagnetic wave and underground media,discuss the problems of resolution and detection depth of UWB electromagnetic method,and provide theoretical guidance for interpretation and practice of UWB electromagnetic method.更多还原