公交车辆的无线电通话的优点是有利于驾驶,减轻列车员的工作以及发生不幸事故时可以迅速呼救,考虑这些优点,在地下铁道中希望安装同样的设备。在地道内的场强测试表明,采用普通的天线,在车辆和固定的被叫电台之间得不到满意的无线电通讯。如果沿着地道敷设一根能在整个长度上辐射并且传输高频能量的电缆(见图1和图2),则可以解 The advantages of a bus’s radiotelephone are to facilitate driving, to reduce the work of a conductor, and to call for help quickly in the event of a tragedy. Taking these advantages into consideration, it is desirable to have the same equipment installed in the Mass Transit Railway. Field tests in tunnels show that with conventional antennas, no satisfactory radio communication is available between the vehicle and the fixed called station. If you lay along the tunnel with a cable that radiates over the entire length and transmits high-frequency energy (see Figure 1 and Figure 2), you can solve