超宽带电磁场传播特性模拟与研究

【作者】 邹倩颖；

【导师】 王绪本；

【作者基本信息】 成都理工大学 ， 计算机应用技术， 2006， 硕士

【摘要】 超宽带电磁场在真空中和空气中的慢衰减规律前人已作过许多工作，也有比较系统的理论。本文的研究是国家自然科学基金“城市灾害救助的超宽带电磁探测方法研究”(No．40374027)项目的一部分工作。为了解决生命救护难题，填补我国这一领域的空白，本文开展了一系列关于在介质中的超宽带电磁脉冲信号的传播特性研究，主要工作包括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，分析辐射的超宽带电磁脉冲在不同介质中的后向散射性质，完成超宽频带电磁脉冲的时域波场分析、波场衰减特性分析，并将其与普通单频连续波作为探测源进行对比，得出超宽带电磁脉冲作为该基金项目辐射源是合适和有利的。本文的特色之处是所有模拟均使用的是数学物理方程的解析解而非一般常见到数值解。 本文围绕着超宽带电磁场辐射传播特性研究，从理论与模拟技术探讨了超宽带电磁场辐射理论、能流密度、与辐射器口径的关系以及在不同介质中特定目标体的散射情况等问题，主要包括以下内容： 1．从时域Maxwell方程出发，利用位势理论，探讨了一般时空源分布近远场超宽带电磁辐射特点和规律。超宽带电磁场的辐射特性可用冲激辐射特性来表示。激励信号的时间宽度决定了电磁场能量的衰减快慢。 2．研究了对超宽带天线口径的激励，结果表明如果观测点在口径的中轴线上则辐射电磁的幅度与天线口径的面积有关，与口径形状无关；如果观测点为空间中任意一点，则激励与电磁幅度有关，即对矩形口径而言，激励长边所产生的电磁场幅度大于激励短边所产生的。 3．基于应用要求，研究了在真空和土壤介质中理想导体对超宽带电磁场的散射特性。由于超宽带电磁场是时变电磁场，入射电场在介质中引起了色散，因此所得入射电场的频率与散射电场的频率不一致。 4．本文使用Matlab进行模拟，对所有计算结果均为解析解，并且都进行了模拟。模拟结果证明了计算结果的正确性与可靠性，从而证明了该项目的可行性。更多还原

【Abstract】 There are many systemic theories on decaying law of UWB electromagnetic field in vacuum and air. This work is one parts of National Science Fund, subject "A study on disaster savingness using UWB electromagnetic detect in city" (No: 40374027). For solving the problem of living security and filling vacancy in the field in our country, this paper are mainly about the simulation and study on the propagation property of UWB electromagnetic field, including: analyzing property of UWB electromagnetic field; through simulation and compute, studying given mechanism; analyzing the property of reflection and scatter of UWB electromagnetic field in different medium, completing the analysis of time domain field and decaying field of UWB electromagnetic field. At last, it compare with the ordinary radar using single frequency continuous wave as the exciting pulse. Specially, all the results are analytical of mathematical-physical equation, not the numerical solution.Studying around the propagation property of UWB electromagnetic field is involved in this paper. The problems are discussed in different extend using simulation and theories, included: radiation theory of UWB, energy density, the relationship of radiation aperture and the scatter of ideal target in different medium.1. The retarded potential is used to derive the transient radiation characterization of general space-time source distribution, based on the time domain Maxwell equation. Transient radiation is characterized by its short-time effect and can be described and represented by projection transform and impulse radiation characteristic. The finite during period of radiated electromagnetic field is decided by the time width of exciting pulse.2. Using Huygens equivalent principle, calculate the relationship between any shade of electric strength and exciting out of ultra-wide TEM antennas aperture radiation field. The conclusion is that, in radiation field, electric strength loading on long border exciting is bigger than short one at the same point.3. Base on application, study on the scattering property of UWB in vacuum and soil medium. As the UWB electromagnetic field is variant with the time going on, the incidence electromagnetic field accrues the dispersion, the frequency of incidence electromagnetic field which we got is not the same with the one of scattering electromagnetic field.更多还原