| As the main channel for transmitting energy and signals,multi-conductor transmission lines(MTL)have been widely used in electrical engineering?electronic engineering?information engineering and other related fields.However,with the higher and higher integration of modern electrical and electronic equipment and the increasing demand of system for mass data signal transmission,the cable harness of MTL is becoming denser and denser and therefore a relatively complex electromagnetic environment in limited space has been produced.The complex electromagnetic environment as an exciting source to interfere with transmission lines,which will causes attenuation and dalay of transmission signals,destroys signal integrity,and leads to the transmission performance of MTLs be affected.Especially in the field of aeronautics and astronautics,some sophisticated electronic systems and equipment will be destroyed seriously,so the importance of improving anti-interference ability of transmission lines is becoming increasingly prominent.In response to the above problems,the paper:(1)The causes of electromagnetic interference of multi-conductoor transmission lines(MTLs)are analyzed.Based on the micr-unit equivalent model of transmission line,the forms of electromagnetic parameters of transmission line are given.An adaptive cross approximation algorithm(ACA)based on the method of moments(MOM)is proposed to extract the uniformly distributed electromagnetic parameters matrix,and the feasibility and accuracy of the ACA algorithm are verified.(2)Based on the theory of Multi-conductor transmission line,the theoretical model of parallel transmission line excited by incident wave is established.The excitation process of external incident time-varying electromagnetic field is analyzed.According to Maxwell equations and the model boundary conditions,the terminal voltage equations of transmission line under the external excitation of total field are derived.(3)The electric field equations under the total field of plane wave are derived,modeling with FEKO software,in the simulated plan wave excitation environment,the loads response characteristics of transmission line ports under different cable structures,cable length,height from the ground and polarization angle of incident wave are studied.The wave shape of induced voltage and current on the load are derived.The simulation results are analyzed and a cable laying method of effectively suppresses plane wave noise interference is proposed.(4)The CST software is used to analyze the response characteristics of high frequency electromagnetic pulse(lightning)as an excitation source to the transmission line,the loads response characteristics of transmission line ports under different cable types,load impedance and incident angle of excitation source are studied.Analyze the simulation results,by properly selecting the cable types and adjusting the layout of the assembled cable,the interference of the lightning electromagnetic pulse is reduced,and the cable transmission performance is improved.(5)The electric field distribution,magnetic field distribution and surface current of the Predator UAV cabin irradiated by LEMP enbironment are analyzed.The cabin model with simplified cables is built,and LEMP is used as the simulated exaction source to solve the induced voltage and current of cables in the cabin.According to the simulation results,in the initial stage of UAV lightning protection design,the indirect effect of cables inside UAV under lightning electromagnetic environment can be reduced and the safety and reliability of UAV operation can be improved by reasonably improving the cable wiring mode. |
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