矿用天线在矩形巷道中应用的最佳波束指标

Optimum beam index of mine antenna used in rectangular tunnels

  • 摘要: 煤矿井巷中,如果天线的波束过宽,则难以有效抑制多径衰落、增大覆盖范围;反之,如果波束过窄,则容易使巷道的边缘区域得不到有效覆盖。利用多波模波导理论,讨论得出理想点源在巷道中的辐射场分布特性是制定矿用天线波束指标的理论依据。在此基础上,推导了井下理想点源的方向函数和半功率波瓣宽度。随后,统计计算结合相关仿真,讨论了巷道波导结构、介质壁电参数、载波频率和电磁波传播距离的影响。根据分析所得,结合相关推导与比较,给出了矿用天线的最佳波束指标:为明显改善巷道内的无线覆盖效果,矿用天线应辐射形状较扁的均值为π/2的Gaussian波束;且天线的半功率波瓣宽度至少要窄于理想点源辐射场在巷道第I,II传播区分界点处的波瓣宽度。

     

    Abstract: In a coal mine tunnel,if the antenna beam is too wide,it is difficult to effectively suppress the multi-path fa- ding and to increase the coverage area. On the contrary,if the antenna beam is too narrow,the edge areas of the tunnel cannot be well covered. Based on the theory of multimode waveguide,it is discussed and concluded that the radiation characteristics of the ideal point source in the tunnel is the theoretical basis for the formulation of mine antenna beam index. Then the direction function and the half power beam width of the ideal point source in the underground roadway are derived. On this basis,and by the statistical calculations and simulations,the influences of the tunnel waveguide structure,the dielectric parameters of the tunnel walls, the carrier frequency and the propagation distance are dis- cussed. According to the analysis,and combining with the mathematical derivation and comparison,the optimum beam index of the mine antenna is given. The results show that in order to improve the wireless coverage significantly,the mine antenna should radiate flat π / 2-mean Gaussian beam. Meanwhile,the half power beam width must be at least narrower than that of the ideal point source when its radiated fields propagate to the break point of section I and II in the tunnel.

     

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