Study On Electromagnetic Interference Of Shielded Cable By Space Electromagnetic Field

With the rapid development of science and technology,the space electromagnetic environment has become more and more complexly because of the increasing of electromagnetic interference sources.Typically,the shielded cable acts as a carrier for transmitting signals between devices,often affected by spatial electromagnetic interference.Therefore,it is important to study the field-line coupling problem of shielded cable.Based on the finite difference time-domain(FDTD)method and the theory of multi-conductor transmission line(MTL),this thesis divides the coupling problem of shielded cables into internal system and external system model.Through matlab programming calculation,the effects of different factors on the coupling response of cable core are analyzed.At first,the theory of FDTD is studied in this thesis.When modeling the external system,the division of the computational domain of the FDTD,the Maxwell basic equation,the conditions of numerical stability,the setting of boundary conditions and the selection of excitation source should be paid attention to.The effects of different grounding modes and different soil conductivity on the coupling response of the shield are analyzed and calculated.Then,the calculation of the relevant parameters of shielded cable and the basic theory of MTL are introduced.The transmission line model is often used to analyze the internal system.The response of the cable core can be calculated through calculating the relevant parameters of shielded cable,deducing the differential equations of the transmission line and setting the boundary condition and the stability condition of the algorithm.The effects of different termination resistors on the terminal current response are calculated and analyzed.Finally,the internal system and external system model are set up to analyze the coupling problem of the coaxial cable.The influences of different soil conductivity and different grounding modes are analyzed and studied.In addition,different soil dielectric constants and electromagnetic wave incident azimuth angles on coupling induced current on the cable core are analyzed and studied.Through the analysis of the induced current,some useful conclusions are obtained,which provide the theoretical guidance for engineering practice.