煤矿井下5G射频源远场辐射防爆安全分析

    Explosion-proof safety analysis of far field radiation of 5G radio source in underground coal mine

    • 摘要: 针对5G通信技术在煤矿井下的推广应用,展开了远场辐射条件下射频电磁能防爆危险分析。首先在假设放电火花特性阻抗与天线内阻阻抗匹配的条件下,建立了环天线的等效模型和放电火花功率的理论计算模型;其次针对3.55 GHz工作频率,通过理论计算设计了窄带宽的环形接收天线和喇叭发射天线,并通过CST仿真软件验证了设计天线的S11曲线;最后搭建了1套收发天线仿真平台,用于估计环天线断点两端的电场强度和积分电压。仿真结果表明:当电火花与天线内阻阻抗匹配时电火花功率最大,且电火花的阻抗值对整个天线的感应电压基本没有影响;远场辐射条件下电火花可获得的功率随着收发天线距离的增大而减小;发射天线功率为100 W及发射天线增益为5时,在远场辐射条件下,产生的理论最大火花功率都不足以引燃瓦斯气体,故标准中的阈功率指标可能过于保守,有待进一步验证。

       

      Abstract: Aiming at the promotion and application of 5G communication technology in coal mines, this paper analyzes the explosion prevention risk of radio frequency (RF) electromagnetic energy under the condition of far field radiation. In this paper, the equivalent model of the loop antenna and the theoretical calculation model of the spark power are established under the assumption that the characteristic impedance of the spark is matched with the internal impedance of the antenna. Secondly, for the 3.55 GHz operating frequency, a narrow bandwidth loop receiving antenna and a horn transmitting antenna by theoretical calculation are designed, and the S11 curve of the designed antenna by CST simulation software is verified. Finally, based on this, a simulation platform for transceiver antenna is built, which can be used to estimate the electric field strength and integrated voltage at both ends of the breakpoint of the loop antenna. The simulation results show that: when the electric discharge machining (EDM) is matched with the internal resistance and impedance of the antenna, the EDM power is maximum, and the impedance value of the EDM has no effect on the induced voltage of the whole antenna, and the power obtained by the EDM decreases with the increase of the distance between the transmitting and receiving antennas. The simulation and calculation show that when the transmitting antenna power is 100 W and the transmitting antenna gain is 5, the theoretical maximum spark power generated under the far-field radiation condition is not enough to ignite the gas. Therefore, the threshold power index in the standard may be too conservative and needs to be further verified.

       

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