Study On Coupling Effect Of Lightning Transient Electromagnetic Pulse

Based on the coupling effect of lightning transient electromagnetic pulse,the ICGS(Impulse Current Generation System)was used to establish the laboratory simulated model of lightning channel to electromagnetically radiate the cable and antenna.We analyze the coupled lightning transient electromagnetic pulse of cable and antenna in the different conditions.The open-circuit voltage wave was used to test the breakdown of the JFET and the MOSFET.The TVS was used as the protection device to analyze the resistance change of each pin of the device.The experiment shows:The cable coupling voltage was linear with the impulse current and increases with the increase of the impulse current.In the time domain,the coupling voltage reaches the maximum and then decreases rapidly.The time range of the received signal is concentrated at 0~ 5?s.The peak voltage appears at about 0.5?s.In the frequency domain,the highest amplitude of the coupling voltage is concentrated at about 1MHz.The center frequency is around 1MHz.As the height or length of cable increases,the coupling voltage peak and energy become larger,and the coupling voltage variation increases per unit impulse voltage.The longer the cable,the faster the peak of the coupling voltage is reached,and the longer the interval time of peak-to-peak.The frequency of maximum amplitude moves toward the low frequency.When the cable length is constant,the cable coupling voltage peak decreases as the buried depth deepens.The energy of lightning current is mainly concentrated in the low-frequency stage,and the difference of energy between two frequency point decreases with the frequency growth.But it also has a certain proportion of the energy in the high-frequency stage.The waveform of fast antenna appears early than magnetic antenna.As the impulse current increases,the amplitude and energy of the antenna generally increase.The effect of the antenna receiving signal is inversely proportional to the distance from the antenna to the current source.The amplitude shows a trend that the forepart is steep and the back is flat.The breakdown voltage of the MOSFET is higher than that of the JFET.For the same pair of tested pins,the breakdown voltage under the open circuit condition is higher than the breakdown voltage when the reverse bias voltage is applied to both ends.The TVS tube provides excellent protection for the FET.When used in an amplifier circuit where higher input resistance and breakdown voltage are desired,an MOSFET can be selected.