为了能更好地分析电磁波沿矿井巷道的传播特性以便能更有效地部署矿井移动通信系统与提高矿井移动通信系统的无线通信质量，针对电磁波沿半圆拱形矿井巷道的传播，提出了一种基于镜像原理的半圆拱形矿井巷道电磁波传播场强预测方法。镜像法是一种基于几何光学理论的射线跟踪法。它将高频电磁波看成光波射线，通过光线的直射、反射等现象，点对点找出发射点与接收点之间电磁波传播的有效传输路径，模拟出电磁波沿矿井巷道的传播过程。所提出的基于镜像原理的半圆拱形矿井巷道电磁波传播场强预测方法首先通过分割半圆拱形顶面来得到镜像法所需的有效反射截面，建立了各截面的平面方程。提出了当发射点和接收点在矿井巷道中的位置确定后，各截面的1次反射点、2次反射点和3次反射点的确定方法以及1次反射线、2次反射线和3次反射线数目的统计方法。基于所分割截面的平面方程，提出了入射波在各截面反射点入射角的计算方法，由此可获得入射波的垂直极化波和水平极化波的反射系数。提出了在接收点处1次反射线、2次反射线和3次反射线场强矢量的计算方法，由此可获得接收点处各次反射波的场强矢量和以及接收点处总场强矢量。仿真结果表明当发射点和接收点在半圆拱形矿井巷道中不同位置时采用所提出的基于镜像原理的半圆拱形矿井巷道电磁波传播场强预测方法可有效统计各次反射线数目与预测接收点处的场强，如得到的采用6面和9面截面分割矿井巷道半圆拱形顶面的场强分布曲线符合电磁波沿矿井巷道传播场强波动的一般规律，且与一些经典的测试结果的趋势相一致。此外，采用所提出的场强预测方法还可以判断电磁波沿半圆拱形矿井巷道传播时将场强分布曲线分割为近源区和远源区的“断点”的位置，在近源区，电磁波衰减较快，在远源区，电磁波衰减较慢。

In order to analyze the propagation characteristics of electromagnetic waves along the mine roadwat better,so as to deploy the mine mobile communication system and improve its wireless communication quality more effectively,a method for predicting the field strength of electromagnetic wave along semicircular arched mine roadway based on the mirror image principle is proposed.Mirror image method is a ray tracing method based on the geometrical optics theory.It regards the high-frequency electromagnetic wave as the ray of light wave.Through the phenomenon such as direct and reflection of light,it finds out the effective transmission path of electromagnetic wave between the transmitting point and the receiving point to simulate the propagation process of electromagnetic wave along the mine roadway.Firstly,the effective reflection cross-section required by the mirror image method is obtained by dividing the semicircular arched top surface with the proposed field strength prediction method,then the plane equation of each cross-section is established.A method is put forward to determine the primary reflection point,secondary reflection point and tertiary reflection point of each section,as well as a statistical method for the number of primary reflection,secondary reflection and tertiary reflection rays when the positions of the transmitting point and receiving point are determined in the mine roadway.Based on the plane equation of the segmented section,the calculation method of the incident angle of the incident wave at the reflection point of each section is proposed,and the reflection coefficients of the vertical and horizontal polarization waves of the incident wave can be obtained.Moreover,the calculation methods of the field strength vectors of primary,secondary and tertiary reflection rays at the receiving point are put forward,from which the sum of the field strength vectors of each reflection wave and the total field strength vectors at the receiving point can be obtained.The simulation results show that the number of each reflection rays can be counted and the field strength can be predicted at the receiving point effectively when the transmitting point and receiving point are in different positions in the semicircle arched mine roadway with the proposed field strength prediction method.For example,the field strength distribution curve with 6 and 9 sections to divide the semicircular arched top surface is consistent with the general law of electromagnetic wave propagation along the mine roadway and is also consistent with the trend of some classical test results.In addition,the proposed field strength prediction method can also be used to determine the location of the "breakpoint" of the field strength distribution curve which divides the curve into near-source and far-source regions when the electromagnetic wave propagates along the semicircular arched mine roadway.In the near-source region,the electromagnetic wave attenuates quickly,and in the far-source region,the electromagnetic wave attenuates slowly.The study plays an important role in the design of underground mobile communication system.

1 反射线数目分析 

   1.1 镜像法原理

   1.2 半圆拱形巷道的分解

   1.3 有效反射线数目的统计方法

2 电磁波场强的分析

   2.1 入射角的计算

   2.2 场强的计算

3 仿真分析

   3.1 反射线的数目

   3.2 接收点处的场强

   3.3 “断点”分析

4 结论