双同轴电缆差分传输方式对干扰的抑制作用

传输线对信号的无失真传输是超宽带测量系统准确获得待测波形和量值的前提之一。基于带宽、功率容量、损耗、屏蔽性能、尺寸等诸多因素,在超宽带测量系统中经常选用同轴电缆作为传输线。指出采用单根同轴电缆传输信号时会引入干扰,分析了干扰形成的原因,通过数值模拟确认了干扰的存在和危害;提出采用两根共地同轴电缆共同传输信号并进行差分处理,可以有效消除传输线引入的干扰,分析了干扰消除的过程和原理,将原数值模拟模型中的单同轴电缆替换为双同轴电缆进行仿真计算,对比验证了双同轴电缆差分传输方式对干扰的有效抑制作用;对双同轴电缆差分传输结构进行了实验测试,结果表明,单根同轴电缆会引入较大的干扰信号,通过两根同轴电缆的共地连接、差分处理,可以有效消除干扰,达到高保真传输要求。

Inhibitory effect of differential transmission with two coaxial cables on interference

The distortionless transmission of the signal through the transmission line is the prerequisite to ascertain the waveform and value of the electromagnetic field under test accurately. In consideration of the bandwidth, power capacity, loss, shielding efficiency and size, the coaxial cable is often used in the UWB measurement system. It is indicated in this paper that the single coaxial cable can produce interference to the transmission signal and the reason of the interference is explained. The result of the computation by a numerical method testifies that the interference does exist and can cause aberration of the signal when one coaxial cable is used as the transmission line. It is put forward that the interference can be eliminated effectively by differential transmission using two coaxial grounded cables. The prominent suppressing effect of the transmission method is certified contrastively by simulation. A dipole with the two coaxial feeder is fabricated and tested. The experiment shows that the single coaxial cable caused obvious interference and the interference was eliminated by the differential operation of the output voltages from the two coaxial cables.