Study On The Coupling Of High-power Electromagnetic Pulses To Transmission Lines

With the rapid development of information today,various electronic devices are emerging in an endless stream.The importance of transmission lines as a necessary medium for information transmission is self-evident.With the continuous development of nuclear technology and the multiple practical applications of strong electromagnetic pulse weapons such as high-power microwave bombs,the coupling of high-power electromagnetic pulses to transmission lines has become a research hot spot.To reduce the harm of high-power electromagnetic pulses to the transmission line,this thesis explores the coupling law of high-power electromagnetic pulse to the cable,and provide a reference for the electromagnetic protection and reinforcement design of the cable.This thesis is based on the CST simulation software and uses the field-path coordination method for simulation.The main research results and conclusions obtained are as follows:(1)In the exposed environment,the coupling effect of high-power electromagnetic pulse on the cable is explored by changing the cable type,the cable height from the ground,the incident direction of electromagnetic pulse,the polarization direction,the cable length,the cable placement form,the gamma radiation equivalent,the braided wire diameter and braided angle of braided shielded cable.The following conclusions were drawn: It is recommended to use a coaxial cable with better shielding effect when selecting a transmission line in a bare environment.The electromagnetic pulse has the strongest destruction power on the cable when the electromagnetic wave is vertically incident and the polarization direction is 0 degree.The height of the cable from the ground should be appropriately reduced to prevent the cable from coupling more electromagnetic fields.The cable should be as short as possible,and it is recommended to use a transient suppressor at the port of sensitive equipment.During the wiring process,cables should be routed at right angles or straight lines.After clarifying the use scenario and protection level of the precision cable and select the electromagnetic pulse corresponding to the radiation equivalent.The larger the braided wire diameter and the smaller the braided angle of the braided shielding layer,the better the shielding effect of the cable.(2)Taking the simple mental cabinet as an example,the coupling effect of high-power electromagnetic pulses on the cables in the open-hole metal case was analyzed by changing parameters such as aperture array's shape,number,wall thickness,and horizontal and verticaldistance of the cables to the hole in the case.The following conclusions were drawn: The principle of opening holes in the shielded chassis is to open more small holes.Diamond holes are recommended for the shape of the ventilation holes of the chassis.The wall thickness should be selected by the material of the chassis and the manufacturing cost when choosing the thickness of the ventilation holes.The cables should be kept as far away from the vents as possible when wiring inside the cabinet.(3)Taking the common outdoor distribution box as an example,modeling and simulation are carried out by referring to the internal structure of the distribution cabinet and the way of cable routing in real life.Adding solder joints,adding sealant,and installing filter circuits are used to counter the coupling of high-power electromagnetic pulses to the transmission line.Then compare it with the coupling effect experienced on the cable when no protective measures are used.Finally,it guides the electromagnetic protection of electronic equipment such as distribution boxes.