Abstract: The balise transmission system is an important part of the train operation control system, and the electromagnetic environment at its installation location is complex. In actual operation, BTM failures caused by electromagnetic interference are frequent, which poses a hidden danger to the safe operation of trains. In order to improve the electromagnetic compatibility performance of balise transmission system, this paper studies the electromagnetic interference of balise transmission system in neutral section and proposes corresponding protection scheme. Firstly, the theoretical analysis of the causes of pantograph catenary discharge in the neutral section is carried out, and the electromagnetic radiation in the uplink frequency band of BTM operating in the neutral section is measured; then the electromagnetic interference coupling law of neutral section pantograph catenary discharge to the on-board antenna of the balise transmission system is studied by modeling and simulation of the train and balise transmission system; finally, according to the characteristics of electromagnetic interference spatial coupling, the protective measures to block its energy coupling path are proposed, the CAU antenna shield is designed, its shielding effect is measured in the laboratory, and the operational test is carried out in the field. The results show that after the CAU antenna is equipped with a shield, the differential mode electromagnetic interference at 3~3.5MHz in the BTM operating frequency band can be reduced by about 20 dB, while the BTM message quality is improved from 0.83 to 0.91. This shows that the proposed shield solution can effectively improve the anti-interference performance of the CAU antenna and will not affect the normal signal transmission of the BTM, thus ensuring the normal communication technology requirements of the balise transmission system. It is expected to reduce the failure rate of the balise transmission system and has a high application value.

Key words: neutral section, pantograph catenary discharge, radiated interference, energy coupling, BTM protection

摘要： 应答器传输系统是列车运行控制系统的重要组成部分，其安装位置处的电磁环境复杂，实际运行中因电磁干扰导致的BTM故障频发，给列车安全运行造成隐患。为提高应答器传输系统的电磁兼容性能，研究分相区应答器传输系统的电磁干扰并提出相应的防护方案。对分相区弓网放电的原因进行理论分析，测量过分相时BTM上行链路频段内的电磁辐射骚扰；通过对列车及应答器传输系统建模仿真，研究分相区弓网放电对应答器传输系统车载天线的电磁干扰耦合规律；最后根据电磁干扰空间耦合的特点，提出阻断其能量耦合通路的防护措施，设计CAU天线定向约束屏蔽装置，在实验室测量其屏蔽效果，并在现场进行运行试验。结果表明，CAU天线加装屏蔽板后，BTM工作频带内的3～3.5 MHz处差模骚扰降低幅度可达20 dB左右，同时BTM报文质量由0.83提高到0.91，说明提出的CAU天线定向约束屏蔽方案能够有效提高CAU天线的抗干扰性能，同时也不会影响BTM的正常信号传输，从而保证应答器传输系统的正常通信技术要求，有望降低应答器传输系统的故障率，具有较高的推广应用价值。

关键词: 分相区, 弓网放电, 辐射干扰, 能量耦合, BTM防护