Ultra-wideband Search And Rescue Detection Numerical Simulation Of Finite Difference Time-domain

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.