空间环境介质对应答器“A”接口性能的影响研究

Study on Influence of Environmental Mediums on Performance of Interface 'A' of Balise System

针对应答器易受周围复杂空间电磁环境影响的问题,研究铁路现场各类损耗介质、无金属区内金属介质对应答器系统的射频场"A4"接口和上行链路场"A1"接口的影响。基于应答器系统简化电路对精简参考环和BTM天线建立FEKO模型,根据实测数据对模型的适用性进行验证,仿真各类损耗介质下电磁波的穿透特性和金属介质下电磁波的分布特征。基于该特性特征和真实应答器的输入输出特性(IO),得到了各类损耗介质和金属介质影响下应答器和BTM天线的有效作用范围。研究结果表明各类损耗介质不能超过其特定厚度,无金属区内的良导体最大横截面不能超过300mm×300mm。无砟道床钢筋网的绝缘节破损会大幅降低"A"接口的传输性能。

Aiming at solving the problem that balises on site are easily affected by electromagnetic environment factors of the complex surrounded space, interferences from loss mediums and metal mediums in metal free zones into interface A4 in the RF field and interface A1 in the uplink field were analyzed. FEKO was utilized to build the balise system models on the basis of simplified circuits. The adaptability of the model was verified ac- cording to the measured data. Referring to electromagnetic waves, their penetration features when diversified loss mediums and their distribution features when in metal mediums were simulated. According to the penetra- tion and distribution characteristics and the input-output characteristics of real balises, the effective operating ranges of the reference loop and BTM antenna in diversified loss mediums and metal mediums were worked out. The research results shows as fllows： Diversified loss mediums are not allowed to exceed their specified thicknesses and the maximum cross section of good conductors in metal free zones should not exceed 300 mm × 300 mm; once damages occur in insulated joints of mat reinforcement of ballastless track bed,the transmission performance will decline sharply at Interface ＇A＇.