EMP作用下的电缆耦合及屏蔽效能试验分析

介绍了三同轴法、线注入法、功率吸收钳法、混波室法等电缆屏蔽效能测试方法.进行了电磁脉冲作用下的同轴电缆和裸线耦合试验,探讨了该环境下同轴电缆屏蔽效能的测试方法.试验分析表明,电缆耦合后的波形为衰减振荡波,振荡周期正比于电缆的电长度,频谱与照射场的频谱不一致,裸线的耦合输出衰减较快.根据试验数据,采用峰值场强法计算的电缆屏蔽效能与峰值电压法的结果吻合,所以可采用峰值场强法对电缆进行电磁脉冲的屏蔽效能测试.电磁脉冲作用下的同轴电缆屏蔽效能较相当频段连续波作用下的略低.

Experimentation and Analysis of Coupling and Shielding Effectiveness for Cable to EMP

Many general methods of measurement for shielding effectiveness of cables are introduced,such as triaxial method,line injection method,absorbing clamp method,reverberation chamber,etc.The shielding effectiveness of cables can be expressed by screening attenuation or transfer impedance.Tests of Electromagnetic Pulse(EMP) coupling to coaxi-al cables and an unscreened wire have been done.The shielding effectiveness of coaxial cable to EMP,which expressed by screening attenuation,is researched by voltage method and electric field method separately for discussing its measuring method.Tests results show that the output of coupling is an attenuated oscillatory waveform.The oscillatory period is propor-tional to the electrical length of cable.The frequency spectrum of oscillatory wave is different from the one of irradiation EMP.And the oscillatory attenuation of coupling output by unshielded cable is very fast.Based on analysis of typical ex-periment data,results of shielding effectiveness calculated by peak value of electric field and by peak value voltage are a-greeable to each other.The shielding effectiveness of coaxial cable to EMP can be measured by the method of electricfield intensity peak value.It is discovered by compared experiments that the shielding effectiveness of coaxial cable to EMP is slightly less than to continuous wave in same frequency band.