井下环状金属结构等效多圈小环天线接收电磁波能量安全性分析

    Safety analysis of electromagnetic wave energy for multiloop small loop receiving antenna equivalent to underground circular metal structure

    • 摘要: 在井下狭小的巷道空间内金属结构集中,如存在长导线、铁轨、绞车钢丝、支架、铁丝环等不同的金属结构形式。井下金属结构可能会通过磁耦合或接收辐射电磁波的方式接收发射天线的电磁波能量。若金属结构存在断点,则在断点处可产生感应电压;若金属结构断点处发生刮擦,则会在断点处以刮擦放电的形式以很低的电压产生刮擦放电火花,有点燃并引爆井下瓦斯气体的危险。金属结构的不同形式如环状金属结构、柱状金属结构等对耦合电磁波能量具有不同的特性。小型环状金属结构在井下广泛存在,具有体积小、摆放与安装自由度大的特点,井下小型环状金属结构等效为环状接收天线接收发射天线电磁波能量的安全性值得关注与研究。本文针对井下环状金属结构电磁波能量的安全性进行了研究,分析了将井下环状金属结构等效为多圈小环接收天线接收电磁波能量的安全性。建立了环状金属结构等效多圈小环接收天线的等效电路,求出了环状金属结构等效多圈小环接收天线负载上消耗的功率。当环状金属结构等效多圈小环接收天线谐振时,小环接收天线的输入阻抗恰好为阻性,可利用环状金属结构等效多圈小环接收天线等效电路求出负载上消耗的最大功率,以及环状金属结构等效多圈小环接收天线与发射天线之间应保持的安全距离。仿真分析了环状金属结构等效多圈小环接收天线的等效半径、导体直径、圈数以及环状金属结构等效多圈小环接收天线和发射天线之间的夹角对负载上消耗最大功率和安全距离的影响。仿真结果表明,安全距离随环状金属结构等效多圈小环接收天线等效半径的增大而增大,随环状金属结构等效多圈小环接收天线导体直径增大变化不明显,随表示发射天线和等效接收天线之间相对高度关系的夹角增大而减小。本文研究可为无线通信新技术在煤矿井下应用的电磁波能量安全性问题提供参考。

       

      Abstract: Along the narrow tunnel underground, metal structures are concentrated, such as long wires, rails, winch steel wires, brackets, wire rings, and other different forms of metal structures. Underground metal structures may receive electromagnetic wave energy from transmitting antennas through magnetic coupling or radiated electromagnetic waves. If there are breakpoints in the metal structure, an induced voltage can be generated at the breakpoint. If there is scraping at the breakpoint of the metal structure, it will generate scraping discharge sparks at a very low voltage in the form of scraping discharge at the breakpoint, which poses a risk of igniting and detonating gas. Different forms of metal structures, such as circular metal structures and columnar metal structures, have different characteristics in coupling electromagnetic wave energy. Small circular metal structures widely exist along underground tunnel with the characteristics of small volume and large freedom of placement and installation. The safety of underground small circular metal structures equivalent to circular receiving antennas receiving electromagnetic wave energy is worthy of attention and research. This paper studies the safety of electromagnetic wave energy of circular metal structures along underground tunnel, and analyzes its safety by equating underground circular metal structures to multiloop small loop receiving antennas to receive electromagnetic wave energy. The equivalent circuit has been established and the power consumption on the load has been calculated by equating the circular metal structure to multiloop small loop receiving antenna. When the multiloop small loop receiving antenna equivalent to circular metal structure resonates, the input impedance of the small loop receiving antenna is exactly resistive. The equivalent circuit of the multiloop small loop receiving antenna equivalent to circular metal structure can be used to calculate the maximum power consumption on the load, as well as the safety distance that should be maintained between the multiloop small loop receiving antenna equivalent to circular metal structure and the transmitting antenna. The influence on the maximum power consumption on the load and safe distance by the equivalent radius, conductor diameter, number of turns, and the angle between the equivalent multiloop small loop receiving antenna of the circular metal structure and transmitting antenna is simulated. The simulation results show that the safety distance increases with the increase of the equivalent radius of the circular metal structure equivalent to the multiloop small loop receiving antenna, and the change is not significant with the increase of the conductor diameter of the circular metal structure equivalent to the multiloop small loop receiving antenna. It decreases with the increase of the angle representing the relative height relationship between the transmitting antenna and the equivalent receiving antenna. This study provides reference for the safety issues of electromagnetic wave energy caused by the application of new wireless communication technologies in underground coal mines.

       

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