铁路沿线山岬对电波传播特性影响分析

Analysis of Influence for the Propagation Characterstics of Radio Waves in Chasm Along Railway

利用波导分析理论及介质表面阻抗的概念，分析了电波在非理想表面的山岬中的传播特性．同时，对频率为９００ ＭＨｚ 的电波在非理想表面的矩形山岬内的传播特性进行了理论计算与分析．计算分析结果表明，环境媒质的相对介电常数对电波传播特性的影响较其它环境参数对电波传播特性的影响要明显得多．非理想表面介质增加了电波传播能量的损耗，缩短了纵向传播距离．在传播的横截面上，水平方向的电场衰减呈现波动分布．

This paper analyzed the propagation charactersitics of radio waves in imperfect surface chasm along railway with the concepts of waveguide theory and surface impedance. The results in the paper have a good approximation as compared with the practical measurements. Meanwhile, the propagation characteristics for 900 MHz radio waves in rectangular chasm with imperfect surface are analyzed and calculated in theory. The results of calculation and analysis in the paper show that the relative permittivity in enviroment medium has more effect on the propagation characteristics of radio waves as compared with other coefficients in enviroment medium. The loss of prapagation energy is raised by the imperfect medium surface in chasm along railway. In the cross section of the chasm along railway the horizontal distribution of the electrical field presents a fluctuating pattern. The reason is the same as that described in the previous practical measurements.