电导率对巷道中电波传播的影响

Influence of conductivity on radio waves propagation in tunnels

为了研究真实巷道中电波传播的特性,必须考虑巷道壁电导率的影响。根据圆形巷道和矩形巷道的电波传播模型,分析了电波衰减率和电导率的关系,并且提出了电导率断点的概念。研究结果显示:当电导率小于断点时,电磁波衰减率几乎不受影响,当电导率高于断点时,电磁波传播特性会有较大的变化。电导率断点主要受传播频率的影响,而与巷道横截面尺寸和极化方式几乎无关。

In order to study the characteristics of radio waves propagation in real tunnels, the influence of the conductivity of tunnel walls must be considered. Based on the radio waves propagation models of circular tunnels and rectangular tunnels, the relation between attenuation and conductivity is analyzed and the concept of conductivity breakpoint is presented. The results show the influence of conductivity is minor and can be ignored when the tunnel wall conductivity value is lower than the breakpoint; however, when the value is bigger than the breakpoint, the influence is greater. The breakpoint is determined mainly by the frequency, and nearly independent of the transverse dimensions of tunnels and the polarization modes.