Research on the safety of 5G electromagnetic wave radiation energy in coal mine
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摘要: 煤矿井下无线射频设备发出的电磁波能量耦合到金属结构上的储能元件中,一旦金属结构存在断点并发生通断接触,积聚的电磁波能量产生的放电火花就可能引起瓦斯爆炸,5G采用大规模多输入多输出(MIMO)技术,存在多个发射天线之间的功率叠加问题,增大了点燃瓦斯气体的可能性。针对该问题,分析了电磁波辐射能量与金属结构的耦合过程,得出了金属负载谐振时放电火花点燃瓦斯气体的条件:如果放电火花在100 μs内释放的能量超过0.28 mJ,则能够点燃瓦斯气体。利用射线追踪法建立了巷道电磁波能量传播模型,通过电磁仿真软件Wireless insite在5G频段下对单天线和多天线射频设备进行仿真,结果表明:电磁波能量以辐射形式传播,工作频率在700 MHz以上的单天线射频设备发出的电磁波能量是本质安全的,而4T4R(4发4收)多天线射频设备与金属结构之间的最小安全距离为0.25 m。Abstract: The electromagnetic wave energy emitted by wireless radio frequency equipment in coal mines is coupled into the energy storage elements on the metal structure. And once the metal structure has a breakpoint and an on-off contact occurs, the discharge spark generated by the accumulated electromagnetic wave energy may cause a gas explosion. 5G uses large-scale multiple-input multiple-output (MIMO) technology, which has the problem of power superposition between multiple transmitting antennas, increasing the possibility of igniting the gas. In order to solve the above problem, the coupling process of electromagnetic wave radiation energy and metal structure is analyzed, and the conditions for the discharge spark to ignite the gas when the metal load is in resonance are obtained. It is found that if the energy released by the discharge spark exceeds 0.28 mJ in 100 μs, the gas can be ignited. The ray tracing method is used to establish a roadway electromagnetic wave energy propagation model. The electromagnetic simulation software Wireless insite is applied to simulate single-antenna and multi-antenna radio frequency equipment in the 5G frequency band. The results show that electromagnetic wave energy propagates in the form of radiation. The electromagnetic wave energy emitted by single-antenna radio frequency equipment with operating frequencies above 700 MHz is intrinsically safe, and the minimum safe distance between 4T4R (4 transmitting and 4 receiving) multi-antenna radio frequency equipment and metal structures is 0.25 m.
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