【作者】 姚善化；

【导师】 吴先良；

【作者基本信息】 安徽大学 ， 电磁场与微波技术， 2010， 博士

【摘要】 空间受限的电磁波传播环境是矿井巷道电磁波传播的基本特征,受巷道中各种因素的严重影响,电磁波在巷道中不能很好地传播。本文旨在对巷道空间结构变化下的电磁波传播特性以及矿井环境参数对传播衰减的影响进行系统研究,建立巷道电磁波传播的一般预测模型,为矿井无线通信系统的规划设计、进一步提高通信可靠性和质量、解决抗多径衰落技术难题等提供必要的理论支持。主要思路和研究内容有以下几个方面：(1)空直矿井巷道电磁波传播特性基于宏观相似性,论文将矿井巷道看作是含有有损介质的波导,采用波导模式匹配WGMD(wave-guide mode matching)理论分析空直类矩巷道中电磁波传播的一般规律,得出矿井巷道电磁波传播有两种场型：Emn(h)模和Emn(v)模,推导出不同边界条件下各传输模的传播常数、传输截止频率的计算公式和衰减率近似解,分析了空直巷道中的电磁波能量损耗。并利用基尔霍夫近似法研究了矿井巷道不规则粗糙面的电磁散射问题,推导出水平极化和垂直极化的散射系数,数值模拟了不同极化方式的电磁散射特性。(2)巷道环境因素对传输特性的影响论文分析了矿井巷道四壁材料电参数随着地层压力、开采深度、材料结构的变化规律,推导出不同异型巷道的电磁波波模方程和传输常数,用有限元方法分析了金属单体支柱和矿井运输机车对传输截止频率的影响,并数值模拟了复杂环境下巷道截面尺寸与电磁波的传播模式、波模截止频率之间、以及变化的环境电磁参数与电磁波信噪比衰减之间的关系。(3)多径信道传播模型的建立论文综合考虑了巷道壁的介电常数等环境因素的影响,讨论了波导模式匹配方法和光波导中的射线光学方法(ray tracing)在预测巷道中电磁波场强分布的优缺点,得出波导模式匹配方法适用于远源区的场强预测,在近源区更适用射线跟踪技术进行场强预测的结论,并利用射线跟踪技术建立了矿井巷道的近源区多径信道预测模型,提出了三维空间的锯齿螺旋射线传播总路径和入射角、反射角的计算方法,讨论了巷道形状与传输频率、传输损耗的变化关系式。(4)基于MIMO的抗多径衰落技术论文对类矩矿井巷道特定频段电磁波的大尺度和小尺度传输损耗特性进行了分析,提出收发两端采用阵列结构的MIMO技术方案用于提高矿井无线通信系统抗多径衰落性能的方法,并建立了两种矿井MIMO信道模型。分析了收发天线的空间相关性对系统性能的影响,最后提出了一种在发射功率受限条件下比特功率递增分配算法。(5)导行电磁波的传播特性分析了巷道中导行电磁波的传播特性,用细导线的表面阻抗近似方法简化井下巷道复杂的电缆表面边界条件描述,采用细电缆近似方法推导了含有轴向导体的巷道导行波的传输衰减近似解,最后研究了漏泄同轴电缆的传递特性,分析了单线波模和双线波模的传播特性,推导出了两种波模的波动方程。论文以一般性的空直类矩矿井巷道为研究目标,通过分析复杂矿井巷道的电磁波传播特性、环境因素对传输特性的影响,揭示了复杂环境的矿井电磁波传播机理,并提出了抗多径衰落技术研究方案,为解决矿井无线通信问题提供了相应的理论基础。更多还原

【Abstract】 The basic characteristic of electromagnetic wave propagation in mine laneway is a space-constrained environment. Electromagnetic wave propagation in mine laneway is very influenced by underground environmental factors and human factors seriously, so electromagnetic wave can not be well disseminated in the laneway.This paper researches the propagation characteristics of electromagnetic waves under changeable spatial structure in different laneway, as well as changing environmental parameters impact on propagation attenuation, establishes a common prediction model of electromagnetic wave propagation in mine laneway, which provide reliable arguments for designing of wireless communication systems, improving the reliability and quality of communication, solving technical problems of anti multipath fading. The main contents and research methods in the following areas:(1) Electromagnetic wave propagation characteristics of mine tunnelsMine roadway will be regarded as a waveguide which containing detrimental media, according to waveguide transmission theory, it is proposed to use WGMD (wave-guide mode matching) and Marcatili to analyze a general law of electromagnetic wave propagation in an empty straight roadway, gets the two field-types:those are Emn(h) model and Emn(v) model, derives the transmission constant of propagation model under different boundary conditions, the calculation formula of transmission cut-off frequency and the approximate solution of attenuation rate,据接收机的反馈信息,发射机为发送符号!!EMBED Equation.DSMT4(?)分(2)(?)wironmental factors on the transmission characteristicsThe electromagnetic field intensity distribution which got by the above method is not for the physical environment and the mine roadway with special configuration (Such as the roadway wall is a low-conductivity mine roadway, and includes power cables, rails, locomotives and hydraulic metal backbone of the road, and the curved roadway, etc.). This paper analyzes the electrical parameters of the roadway walls changed with formation pressure, mining depth and material structure, derives the electromagnetic wave mode equation and transfer constants under different conditions according to the characteristics of special-shaped roadway such as class matrix roadway, circular roadway and bended roadway, etc. analyses metal single pillar and transport locomotive made impact on transmission cut-off frequency using finite element method, and numerical simulates the relationship among the roadway cross-section size, communication model of electromagnetic waves and wave-mode cut-off frequency in complex environment of roadway, as well as the relationship between the electromagnetic parameters of changing environment and the attenuation of electromagnetic wave signal to noise ratio.(3) The establishment of Multi-path channel transmission modelAs the underground roadway is limit propagation space, multi-path propagation is the significant characteristics of mine electromagnetic wave propagation because of the rough roadway walls and obstacles which is more important.This paper takes the impact of environmental factors such as the dielectric constant of roadway wall into account, discusses the advantages and disadvantages of the electromagnetic field intensity distribution by using the waveguide mode matching method and ray tracing in predicting roadway, pointes out that the waveguide mode matching method can be applied field strength prediction of the far-field zone, ray-tracing method is more suitable in the near-field area, establishes a near-field zone with multi-path channel prediction model of mine roadway using ray-tracing method, proposes three-dimensional zigzag spiral light transmission path and the calculation method of incident angle and reflection angle, and discusses the changing relationship among the shape of the roadway, transmission frequency and transmission loss.(4) Anti-multi-path fading based on MIMO technologyThis paper analyzes transmission loss properties between large scale and small scale of specific band of electromagnetic waves in class matrix roadway, explores some of the advantages of MIMO technology, which has possibility to be used in wireless communications mine according to the application environment of underground mobile communication terminal, signal processing complexity and portability requirements, proposes the idea of using the array structure of sending and receiving ends of MIMO technology to enhance the anti-fading performance of mine wireless communication systems and establishes two mine MIMO channel models. This paper also analyzes spatial correlation of the transceiver antenna which has effect on system performance, proposes increasing the bit-power allocation algorithm in terms of transmission power is limited finally. The algorithm allocates the largest part of power to the sub-channels which have maximum eigenvalue by calculating the peak power of all sub-channels to meet the target bit error rate, improve the use efficiency of transmission power and the capacity of the system obviously.(5) The propagation characteristics of guided electromagnetic wavesThe actual roadway of the mine contains a lot of axial conductors such as cables, pipes, rails and power lines. The reliable solution is setting up one or more of guided-wave cable in order to achieve low-loss, long-distance transmission. This paper analyzes the propagation characteristics of guided electromagnetic waves in the roadway, simplifies the description of the complex cable surface boundary conditions of underground roadway with surface impedance approximate method of thin wire, derives the approximate solution of guided wave transmission attenuation in roadway which contains axial conductors using approximate method of thin cable, finally, this paper Studies the transmission characteristics of leaky coaxial cable, analyzes the propagation characteristics of single-mode and two-wave-mode, and derives the wave equation of two-wave model.更多还原