电缆电磁脉冲屏蔽效能的辐射法测量

Measurement of shielding effectiveness of cable with electromagnetic radiation method

分析了电缆电磁脉冲屏蔽效能传统测量方法的局限,提出了辐射法测量电缆电磁脉冲屏蔽效能的试验方法。该方法根据互易性原理,将屏蔽效能定义中的电缆耦合场测量转变成电缆辐射场测量。通过电缆屏蔽前后辐射场的测量,得到电缆的电磁脉冲屏蔽效能。以SYV50-5同轴电缆为对象,采用辐射法研究了其对电磁脉冲的屏蔽效能,试验取得了较理想的效果。由于互易性原理对介质空间除了线性没有特别的要求,对于传统方法很难处理的多芯电缆、双屏蔽电缆、特种电缆等的屏蔽效能测量,辐射法测量同样有效。通过改变传感器的类型测量辐射磁场,还可以得到电缆对磁场的屏蔽效能。

The limitations of conventional methods used to measure cable＇s shielding effectiveness are analyzed. The meas- urement of shielding effectiveness of cable with electromagnetic radiation method is presented based on the reciprocity theorem. According to the theorem and the definition of shielding effectiveness, the method can be used to measure cable＇s shielding effec- tiveness through the measurement of radiated field instead of the measurement of coupling field. The electromagnetic radiation method was used to measure the shielding effectiveness of cable with SYV50-5 cable for electromagnetic pulse. The measurement proves to be very efficient in cable＇ s shielding effectiveness test. As it has no special requirements but linearity on the media space, the reciprocity theorem can be applied reliably. The method can be used to measure the shielding effectiveness of various cables, such as multi-core, double shielding and other special cables. The cable＇s magnetic shielding effectiveness can also he ac- quired through the measurement of radiated magnetic field by changing the sensors.