The Shape Factor Analysis Of Tunnel Electromagnetic Wave Propagation

With the development of time, the mine mobile communicationis more and more important. With the development of the energy industry, especially the development and utilization of mineral resources, mine mobile communication appears more and more powerful. It can not only help prevent, deal with all kinds of sudden accident, more important is to provide a strong guarantee for work safety, promote the coal mine safety and high efficiency production. So, the research on wireless communication of mining has an important meaning abstractly and valuably. Based on the research findings of predecessors, a detailed study of the influence of the shape factor on electromagnetic waves propagation in tunnels. And some useful conclusions are obtained.Firstly, this dissertation detailed introduces the electromagnetic wave propagation model of rectangular tunnel and ellipse tunnel, it raises the rate of attenuation of electromagnetic wave formula of rectangular and ellipse tunnel, provide the theoretical basis for the following derivation of shape factor and the electromagnetic wave attenuation rate formula. Secondly, some inherent propagation property of electromagnetic wave is introduced, this paper discussed the communication frequency and the tunnel section size influence on the electromagnetic wave attenuation rate, and thus leads to the concept of tunnel shape factor. Finally, a brief introduction to the research methods of this paper--software simulation method.Then this paper mainly studies the influence of the shape factor on electromagnetic waves propagation in tunnels, it analyzes the rectangle, ellipse, arched tunnel, derived from the shape factor and the electromagnetic wave attenuation rate formula. And then discusses the relationship between the frequency of electromagnetic wave, the cross sectional area of surrounding rock of tunnel, the dielectric constant and the shape factor of electromagnetic wave attenuation rate, some useful conclusions are obtained: The shape factor of the minimum attenuation has a relationship with the relative permittivity of the tunnel walls, and not with the cross sectional area and frequency. When the relative permittivity of different shape tunnels is increases, the shape factor is also increases.Finally, this paper studies the tunnel shape factor in the equivalent analysis method. The semi-circular arched and trapezoid tunnel as an example, this paper proposes a new equivalent scheme analysis, with prior equivalent analytical method is compared.The innovation of this paper is to put forward the concept of tunnel shape factor, research on the the influence of the shape factor on electromagnetic waves propagation in tunnels. And apply it to the equivalent analysis method analysis of special section tunnel.