Study Of Field Line Coupling Effect Near The Ground Under The Action Of Strong Electromagnetic Pulse

With the rapid development of high power microwave weapons in recent years,the threat of electromagnetic interference in the communication electronics of modern battlefield is becoming more and more serious.At present,electromagnetic interference sources in modern battlefield are mainly based on high altitude nuclear electromagnetic pulse,high power microwave,and ultra wideband.Transient strong electromagnetic pulses are susceptible to damage to sensitive circuits and devices,which is easily accessible by means of a transmission line to the electronic communication system.In conventional electromagnetic interference protection,the cable reduces its electromagnetic interference by adding a shield.However,due to the high energy of strong electromagnetic pulses,part of the pulse energy can still be coupled into the core,resulting in sufficient damage to the transient current of the sensitive circuit at the downstream stage.Therefore,it is necessary to accurately calculate the shielded core current.For strong electromagnetic pulses,high altitude nuclear electromagnetic pulse appears earliest,so the research on field-line coupling effects of cable under high altitude nuclear electromagnetic pulse is relatively mature.However,the research on the field-line coupling effect of emerging ultra-wideband and highpower microwave irradiation cables is less or even unattended.The three types of strong electromagnetic pulses have different characteristics and cannot be confused.So it is necessary to make an accurate analysis of field-line coupling effects of high-power microwaves and ultra wideband.In this paper,a new method based on time-frequency domain equivalence and minimum phase principle to solve the time domain current of shielded cable is proposed for the lack of research at home and abroad.The effectiveness of the new method under nuclear electromagnetic pulse is verified by simulation.In order to compare the coupling effect of the field lines under the action of the nuclear electromagnetic pulse,the field-line coupling effect under the action of high-power microwave and ultra-wideband is finally analyzed through simulation.First,this paper has conducted deeply research on three kinds of strong electromagnetic pulse,detailed introduction of the nuclear electromagnetic pulse,high power microwave,ultra-wideband generation mechanism and their characteristics.The characteristics of time and frequency domain are studied according to the waveform of time and frequency domain;Based on the field-to-single line physical model,the transmission line equation under strong electromagnetic pulse was deduced and solved;The local coordinate system and the general coordinate system are established to analyze the electromagnetic environment near the ground in two cases,which consider the ground reflection and the ground reflection without considering the ground reflection.Combining the transmission line equation and using the inverse Fourier transform,the time domain response current in both cases is obtained.Finally,the accuracy and necessity of considering ground reflection are verified using software.Second,according to the transmission line formula,the time domain current of the shield is solved,and a new method based on time-frequency domain equivalence and minimum phase principle is proposed to solve the time domain current of the shielded cable core.The effectiveness of the new method is verified by simulation and testing of the shielding effectiveness of a typical shielded cable,the coaxial RG58C/U.Third,The simulation validates the applicability of the high-power microwave and ultrawideband to the transmission line equation.The variation of the coupling current between single wire near the ground with high power microwave and ultra wideband is studied,including the length of the cable,the height above the ground,the diameter of the cable,and the direction of incidence of the electromagnetic field.Compare this effect with nuclear electromagnetic pulse.