空拱形巷道中电磁波的传输特性

Propagation Characteristic of Electromagnetic Wave in Empty Arched Tunnel

分析了电磁波在空拱形巷道中的传输特性。运用波导理论并结合数值计算法推导出巷道内的衰减率计算公式。对传输频率、巷道横截面以及围岩介质电参数对电磁波传输衰减率的影响做了软件仿真。结果表明:在300～3000MHz特高频段,工作频率越高衰减越小,巷道横截面积越大衰减率越小,围岩介质的相对介电常数越大,衰减越大,且介电常数的变化对垂直极化波的影响大于水平极化波,围岩介质的电导率对衰减的影响不大,可忽略不计。

The propagation characteristic of electromagnetic wave in an empty arch tunnel was analyzed. Using the waveguide theory and the numerical calculation method, the formulas of attenuation rate in an empty circular tunnel were given. In addition, software simulation was done to simulate the influence of transmission frequency, cross sections of tunnel and dielectric parameter of surrounding rock on attenuation rate of electromagnetic wave transmission. The results showed that at 300 -3000MHz the higher the work frequency was, the smaller the attenuation rate was ; the larger area of cross section was, the lower attenuation rate was. The attenuation rate increased as the relative dielectric constant of surrounding rock enlarged, and the effect of variation of the dielectric constant on vertically polarized wave was greater than that of horizontally polarized wave. The influence of surrounding rock conductivity on the attenuation was minor and could be ignored.