列车顶部对半椭圆形隧道中电磁波截止频率的影响

Effect of train's top on the cut-off frequency of semi-elliptical tunnel

列车的存在改变了隧道的截面形状和尺寸,从而影响了电磁波的截止频率。本文在对列车-隧道导波问题进行物理建模的基础上,应用FEM法研究了列车的高度、位置以及半椭圆形隧道和列车顶部椭圆的偏心率的变化对半椭圆形隧道电磁波截止频率的影响。其结果对铁路隧道、公路隧道、煤矿井下巷道等有限空间的无线通信有重要的参考价值。

The cut-off frequency can be changed by a train in the tunnel,which seriously affected the transmission of electromagnetic wave because of the modification of the shape and size of the tunnel's section.In this paper,the train-tunnel is constructed as a model of waveguide and the boundary value problem is obtained.The FEM is used to analyze the semi-elliptical tunnel's cut-off frequency when the train's height,width,location is changed in the tunnel,as well as the changes in eccentricity of the semi-elliptical tunnel with the train's top.According to the calculation of the cut-off frequency,the variational characteristic of cut-off frequency in the tunnel is studied.The achievement has an important reference value to wireless communication in finite space of railway-tunnel,highway-tunnel and mine-tunnel.