Study On Coupling Characteristics And Anti-damage Technology Of Navigation Receiver In Strong Electromagnetic Field

With the development of military technology,electromagnetic pulse weapons have gradually appeared in modern war,which greatly threaten the survivability of communication equipment such as satellite navigation receivers.Especially for the RF front-end circuit,the threat will be more prominent.Higher power electromagnetic interference signals entering sensitive components of the RF front-end circuit,such as low-noise amplifiers,will significantly interfere with their normal operation or even damage them,which will lead to the failure of navigation receiving system.Therefore,it is important to study the coupling process of electromagnetic pulse to satellite navigation receiver and the protection technology to improve the anti-damage ability of the equipment in electromagnetic field.Based on understanding the characteristics of electromagnetic pulses,this thesis studies the coupling theory between electromagnetic pulses and receiver cables by means of the theoretical analysis simulation,as well as the influence of the coupled signal on the receiver RF front-end circuit.Furthermore,the anti-damage power limiter and low-noise amplifier are designed based on the most serious interference situation,which provides the feasible technical method for improving the anti-electromagnetic damage ability of the equipment.The researches are as follows:Firstly,this thesis analyzes the time domain and frequency domain characteristics of high-power microwave electromagnetic pulse,high-altitude nuclear explosion electromagnetic pulse and ultra-wideband electromagnetic pulse.And analyzes the radiation propagation characteristics of electromagnetic pulse and the damage effect caused by electromagnetic pulse.Then,the coupling theory between the electromagnetic pulse and the receiver cables is studied by means of the theory analysis and simulation.First,this thesis analyzes the coupling physical model between the electromagnetic pulse and cables,the transmission line equation is derived,and the coupling voltage and current on the cable are calculated.Secondly,the coupling simulation model between the electromagnetic pulse and cables is established.By changing the pulse type,incident direction and cable parameters,the coupling rule and the most serious coupling degree are obtained.The disturbance signal is injected into RF front-end circuit and low-noise amplifier model respectively,and the effect of interference signal on the circuit is obtained.Finally,the anti-damage indictors is determined according to the interference strength of electromagnetic pulse.By analyzing the influence of diode parameters and circuit structure on the performance of limiter,the selection of diode and the design of circuit structure are completed.Finally,the two-stage cascade active limiting circuit based on PIN diode is determined and simulated.In addition,according to the requirements of the receiver,the half wavelength stepped-impedance resonator(SIR)hairpin filter and two-stage low noise amplifier are designed respectively.At last,the low noise amplifier with limited power is finally developed and simulated.The simulation results show that each device can protect the circuit from being damaged.The power limiter has a threshold power of 0d Bm,a response time of 2ns,a power capacity of 30 d Bm,and the output power is 3.5d Bm at this time;The input power is less than-7d Bm and the amplification gain is 31.12 d B.When the input power is greater than 0d Bm,the output power is limited to 25 d Bm.For the limiting low-noise amplifier,when the input power is less than-7d Bm,the amplification gain is 31.12 d B,and when the input power is greater than 0d Bm,the output power is limited to 25 d Bm.