同轴电缆连续波电磁辐照的终端负载响应

为了揭示设备互连电缆在连续波电磁辐照条件下的耦合响应规律，以典型射频同轴电缆为受试对象，将电缆终端连接的设备（系统）等效为负载，通过对其进行连续波电磁辐照效应试验研究，分析了受试电缆长度、终端负载状态等对同轴电缆终端负载响应规律的影响。结果表明:同轴电缆对电磁辐照响应具有选频特性，终端负载响应电压的峰值出现在电缆相对长度为1/2整数倍的频点；同轴电缆受到连续波电磁辐照后，感应皮电流通过转移阻抗转化为芯线与屏蔽层之间的差模感应电压，而这一感应电压源的内阻就是同轴电缆的特性阻抗；同轴电缆终端负载阻值的变化不会对其连续波辐照响应曲线的变化规律产生影响，终端负载与等效感应电压源内阻上的电压响应满足分压原理； 同轴电缆皮电流处于谐振状态时，两波节之间的分布感应电压同向，可等效为一个感应电压源，对同轴电缆终端负载响应起直接作用的电压源是最靠近终端负载的等效感应电压源。

Terminal load response law of coaxial cable to continuous wave electromagnetic irradiation

In order to study the coupling response law of continuous wave electromagnetic irradiation to coaxial cable, the typical RF coaxial cable is selected as the object under test. The equipment or subsystem connected by coaxial cable is equivalent to a lumped load. Continuous wave irradiation effect experiments under different conditions are carried out to analyze the terminal load response law of coaxial cable. The results indicate that the coaxial cable has a frequency selecting characteristic under electromagnetic irradiation, and the terminal load response voltage peak appears at a series of discrete frequency points where the test cable’s relative lengths equal to semi-integers. When the coaxial cable is irradiated by continuous wave, the induced sheath current converts to the differential-mode induced voltage between inner conductor and shielding layer through transfer impedance, and the internal resistance of induced voltage source is the characteristic impedance of the coaxial cable. The change in terminal load value has no influence on the response curve. The voltages on the terminal load and the internal resistance of equivalent induced voltage source obey the principle of voltage division. Moreover, when the sheath current on the coaxial cable is in resonance, the distributed induced voltage between adjacent current nodes is in the same polarity, which can be equivalent to a single induced voltage source. The induced voltage source which is adjacent to the terminal load plays the leading role in the irradiation response process.