Study On Continuous Wave Illumination Method For Electromagnetic Pulse Effect Analysis

With the increasing complexity of the electromagnetic environment in electronic battlefields,the requirements for anti-interference of electronic equipment are also increasing.To ensure the normal operation of weapon equipment and systems in war environments,it is necessary to test the sensitivity of electronic equipment under nuclear electromagnetic pulse radiation.There are three commonly used test methods for system electromagnetic pulse effect: threat-level illumination,pulsed current injection and Continuous Wave(CW)illumination.As an alternative test method of threat level test,CW illumination method can be widely used in the study of the failure mechanism of the tested system and the prediction and analysis of the electromagnetic pulse effect of the tested system because it will not cause damage to the tested system.However,the key technologies such as the illuminator design of CW illumination method,the equivalence of CW illumination method and threat level illumination method need to be further studied.This article focuses on the optimization design of a typical antenna in CW illuminator-an elliptical antenna.At present,the horizontal polarization of elliptical antennas still adopts the same loading scheme as the vertical polarization.However,the same loading scheme is difficult to adapt to changes in antenna boundary conditions.At the same time,the change in polarization direction makes uniform loading no longer the optimal loading scheme.Through non-uniform loading,the performance of the field distribution in the working area of horizontal polarization antennas can be further improved.The current traditional antenna simulation algorithms have a slow computational speed and cannot support the operation of optimization algorithms for antenna non-uniform loading schemes.Therefore,the development of fast antenna simulation algorithms is also urgent.This article will redesign the elliptical antenna through non-uniform loading to optimize the horizontal polarization performance,and achieve the first large-scale elliptical skyline testing system in China,including testing environment construction and data post-processing.The main research contents of this paper are as follows:1.A simulation algorithm combining Method of Moments(Mo M)and Finite Difference Method(FDM)is proposed to solve the low efficiency of traditional calculating the field distribution of CW illuminator.The fast calculation of field distribution around illuminator with any ellipse size,any loading mode and various polarization directions is realized and significantly improve the computational efficiency of field distribution.Based on the surface electric field equation of CW illuminator,the mathematical model is established by vector potential equation and boundary conditions.The impulse function and delta function are set as basis function and weight function respectively to establish the current equation.The equation is simplified by the image theory and the current distribution is determined by the non-uniform finite difference method.The field distribution is determined by superposition theorem.The accuracy of the simulation algorithm is verified by the self-made CW illuminator.2.Aiming at the problem of calculating the working region of CW illuminator,an algorithm based on wave impedance determination is developed to determine the working region,and the fast locking of the working region of any CW illuminator is realized.Aiming at the vertical polarization and horizontal polarization of CW illuminator,the wave impedance distribution after loading is analyzed,and the influence of loading distribution on the selection of working region is studied.The selection principle of the wave impedance of the monitoring point is analyzed.Based on the calculation results,the relationship between the working region and the illuminator structure size under different polarization states is summarized and it lay the foundation for the subsequent development of CW irradiation antenna testing system construction.3.In order to improve the wave impedance characteristics of horizontal polarization of CW illuminator,the non-uniform loading scheme of CW illuminator is proposed.The vibrators on both sides are symmetrically divided into ten regions,and each region is loaded with different densities.The upper limit of loading density is determined according to the dimension parameter of loading unit.Genetic Algorithm(GA)and Particle Swarm Optimization(PSO)were used to optimize the loading configuration,and the advantages and disadvantages of the two algorithms were compared.The simulation results show that the standard deviation of impedance distribution of non-uniform loading scheme is reduced by 14% compared with the uniform loading scheme.4.Based on the non-uniform loading scheme of CW illuminator,the CW illumination system is developed by conquering the key technologies such as the design of wide-band loading unit and the construction of non-metallic antenna frame.An appropriate ferrite loading unit is designed,the vibrator is developed according to the non-uniform loading scheme under horizontal polarization,and a glass fiber reinforced plastic antenna frame is designed.In order to achieve approximate total reflection on the ground of the platform,a grounding net is designed,and an electromagnetic field probe and a surface current probe are developed.The non-uniform loading scheme and the size of the working region are verified by the selfdeveloped CW illumination system.The results show that the performance of the illuminator is basically consistent with the simulation data,and the design requirements are met.5.In order to analyze the equivalence of CW illumination and Electromagnetic Pulse(EMP)illumination,a set of EMP response prediction method is designed,and the sampling frequency and sampling number requirements of CW illumination are analyzed.The accuracy of the minimum phase method in CW illumination is studied.The simulation results show that the minimum phase method can restore the time domain signal basically.Finally,the equivalence of CW illumination method and EMP illumination method is verified by experiments.The results show that the estimated response of CW illumination method is basically restored to the actual state,and the equivalent results of the two methods are related to the test environment.When the illuminator/environment used by the two test methods is similar,the coincidence degree of the results of the two test methods is the highest.This paper innovatively proposes a non-uniform loading method for elliptical antennas,which effectively improves the performance of field distribution;And by studying the size of the working area of irradiation antennas of different sizes,a general conclusion on the positioning problem of the working area is obtained,which provides theoretical support for the design of CW irradiation antennas in the future;Finally,the first CW irradiation testing system for elliptical antennas in China was established,laying the foundation for the study of equivalence experimental methods.