| With the widespread use of the sensitive electronic device,a great attention has been attracted on the study of the coupling between the electromagnetic(EM)pulse and the illuminated device.The EM pulse will cause the EM interference to the electronic components inside device through heat dissipation holes,connecting cables,external antennas,etc.Even if electronic devices has been designed according to electromagnetic compatibility law,the transmission lines without shield between the device will still be attacked by the EM pulse.The coupling shock will arrive and disturb the sensitive component in device through the transmission line,resulting in the damage and nonnormal operation of electronic component.Therefore,it is of great significance to research on the transient coupling of the electromagnetic pulse to the transmission lines for the EM protection and compatibility design of electronic device.In this paper,aiming at the coupling problem of the wideband electromagnetic pulse to multi conductor transmission line,time-domain iterative schemes of transient voltage on transmission line are presented based on the leapfrog idea of finite difference Time Domain(FDTD)method.The influences of the parameters of incident wave,load resistance,and transmission line on the EM coupling are analyzed in detail.The specific contents are shown as follows:1.The theories generating the lightning pulse and nuclear pulse are introduced in section 1.The time domain waveforms and waveform parameters of the EM pulse are elaborated,which are generated using the double exponential function.The potential destructive capabilities of the high power electromagnetic pulse(HPEMP)on electronic equipment and communication systems are described,including EM interference,device damage and system collapse,etc.2.According to the EM wave theory,the transmission line equations in the time domain are derived in case of external field excitation.Then the transmission line equations are discretized based on the FDTD idea,obtaining the time-iterative equations for the transmission line voltage and current.The stability conditions are analyzed in the FDTD simulation of transmission line,and the truncation condition of FDTD is deduced by applying the Thevenin′s theorem.Finally,the incident wave source is injected in the FDTD domain through use of the superposition of directly illuminated field and reflected field by ground.The electromagnetic interferences form the EM pulse are calculated by using the FDTD method to obtain the voltage on the terminal load.Moreover,the coupling laws are presented for different incident angle.3.An FDTD solution scheme is given for a grounded two-conductor transmission line,in which the incident excitation wave field of the transmission line is obtained by superimposing the directly irradiated field with the reflected field of ground.The results of the electromagnetic coupling of the grounded two-conductor are numerically calculated for the lossy and lossless case.The variation laws of coupling voltage with transmission line length,load resistance and the distribution resistance per unit line length are elaborated in detail.4.An FDTD scheme are described for the model of grounded multi-conductor transmission lines,where fully considering the EM contribution among the multi-conductor transmission line.The iterative equations in matrix form are deduced to compute coupling voltage on the terminal load of transmission line.The electromagnetic coupling results are numerically simulated for double exponential pulse incidence.Meanwhile,the influence laws of the transmission line height from ground,transmission line radius and transmission line spacing on electromagnetic interference are discussed in this paper. |
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