| Aiming at the problem that the 2.4G band antenna is coupled in the strong electromagnetic pulse environment and the overvoltage caused by the damage to the back-end equipment,this paper simulates the electric field environment of the strong electromagnetic pulse through the experimental equipment,and explores the coupling characteristics of antennas of different lengths,different radomes and different structures in the electromagnetic pulse environment.Then,according to the characteristics of the coupling waveform,the nanosecond-level high-voltage square wave was used as the pulse source,and the damage mechanism of the voltage regulator diode commonly used in the RF circuit at the back end of the antenna under the square wave pulse was investigated from the perspective of damage voltage and damage energy.Secondly,the response characteristics of the surge protection device under strong electromagnetic pulse were studied,the 2.4G band hairpin microstrip line filter was designed by HFSS software,and the strong electromagnetic pulse protection circuit was designed in combination with the surge protection device;finally the relevant parameters of the protection circuit were optimized by ADS software simulation,and the protective device was tested according to GJB 9408-2018 standard.The conclusions reached by the article are as follows:（1）The coupled voltage waveform of the antenna in the strong electromagnetic pulse environment is a damping oscillation wave type,the first wave peak is the largest,the rise time is a few nanoseconds,the coupling signal frequency is mainly concentrated in 0～130MHz,the coupling voltage peak has a linear relationship with the electric field strength,and the coupling energy has a quadratic function relationship with the electric field strength.（2）The coupling voltage of the antenna is positively correlated with the length of the antenna,and with the increase of the length of the antenna,the coupling voltage in the unit electric field strength also gradually increases;The peak value of antenna coupling voltage of different radomes is not much different,and the commonly used ABS plastic and FRP radomes cannot reduce the coupling effect of electromagnetic pulses;The rate of antenna coupling electromagnetic pulse is related to the antenna structure,and the peak relationship of the coupled voltage of the antenna per unit electric field strength is FPC antenna>copper rod antenna>PCB antenna.（3）With the increase of square wave pulse voltage,the voltage stabilization performance of the regulator tube decreases,and the damage form is manifested as a decrease in the voltage stabilization value,an increase in leakage current,and a distortion of the volt-ampere characteristic curve;Diode damage energy is not a constant value,with the increase of pulse width,the damage energy threshold decreases,when pulse width 20ns square wave pulse injection,BZX55C15V diode damage energy is 3.87*10-3J,pulse width 40ns square wave pulse injection,damage energy is 8.78*10-4J.（4）Under the injection of strong electromagnetic pulse current,three kinds of protection devices（GDT,MOV and TVS）can respond,but the protection effect of a single device is not good,the GDT is placed in the front end of the protection circuit,the back end adopts multi-stage filter circuit and TVS tube combination,the distributed capacitance of the TVS tube will have a great impact on the circuit insertion loss,the distributed capacitance of the TVS tube as a parameter design into m deduction type high-pass filter can effectively reduce the transmission loss of the signal.（5）According to the standard"GJB 9408-2018 Technical Requirements and Test Methods for Electromagnetic Pulse Protective Devices at Electrical Inlet Terminal",the protective devices were measured,and the results met the A and B suppression levels in the standard. |
