Analysis Of Electromagnetic Field Distribution Characteristics Inside And Outside The Aircraft Under Radar Irradiation

In modern society with the rapid development of information technology,the aircraft system is becoming more and more integrated and intelligent,meanwhile,its flight environment is becoming more and more complex.The intelligent trend of aircraft makes the integration of aircraft electronic equipment getting higher and higher.The complex circuit structure and program logic make its electromagnetic sensitivity continuously improved,in order to ensure the normal operation of the system,people pay more and more attention to the electromagnetic compatibility of the aircraft.The electromagnetic compatibility performance of the aircraft plays an important role in the design,production,safety,and other aspects.In this thesis,the topic is selected according to the relevant contents of the scientific research project.Based on the situation that the aircraft is used for power line inspection and railway inspection along the Qinghai-Tibet Railway,considering that radar signals may affect the aircraft in the surrounding military activities,and the existing aircraft electromagnetic compatibility test does not use radar signals as interference factors.Therefore,this thesis uses radar as the radiation source,and analyzes the characteristics of electromagnetic field distribution and surface current distribution inside and outside the fuselage when it irradiates the aircraft.In this thesis,the main research contents of the radar signal affecting the electromagnetic compatibility of aircraft are:First of all,the research focuses on the radar composition,launch characteristics and launch field distribution these three aspects.Among them,the focus is on phased array radar as the radiation emission source that stimulate the electromagnetic field around the aircraft.Through chirp signal research,antenna array element simulation,phased array antenna design and pattern simulation,radar launch field distribution is obtained.At the same time,the frequency,gain,power,angle and other parameters of the radiation source are determined,which provides the basis for the selection of electromagnetic wave parameters irradiating the aircraft.Secondly,the electromagnetic simulation software is used to establish the electromagnetic model of the aircraft,at the same time,the theoretical field strength value of the radar irradiated to the aircraft is calculated.Then the electromagnetic field distribution and surface current distribution inside and outside the aircraft under radar irradiation are simulated.By changing the irradiation angle,irradiation direction,polarization direction,frequency and signal intensity of the radar electromagnetic wave propagating to the aircraft,the electromagnetic field characteristics are analyzed,the simulation results are compared,and the laws are summarized.Then,the electromagnetic coupling effect of the aircraft slot on the inside of the fuselage is analyzed.Changing the structure of the aircraft,set up an aircraft model with a gap,internally arranged parallel cables,and use electromagnetic simulation software to simulate the cable port voltage under different gap sizes and different radar wave irradiation angles.Focusing on the analysis of the impact of external electric field on internal cables.Summarizing the electromagnetic field distribution,formation reasons and performance rules,the simulation results show that the electromagnetic field and surface current of the surface directly irradiated by the radar wave are the largest.In addition,the electromagnetic field and surface current at edges and tips of wings and tail with small curvature radius and large bending degree of the aircraft fuselage are large,and the electromagnetic coupling at the skylight is obviously larger than other parts inside the fuselage.The cables inside the fuselage are also affected by electromagnetic waves,the larger the gap size,the greater the cable port voltage.It can be seen that among the impact of the external electromagnetic environment on the aircraft,these parts are relatively important and sensitive,and it should be given key protection in design and production.The simulation and analysis in this thesis provide a theoretical basis for the electromagnetic compatibility design of the aircraft and how to improve the environmental adaptability of the aircraft.