Research On Electromagnetic Shielding Characteristics Of Slotted Box In Complex Electromagnetic Environment

At present,our country is developing rapidly in the field of science and technology,and all kinds of electrical and electronic products have penetrated into all areas of our lives.The electromagnetic energy generated by these products in the working process will cause electromagnetic interference(EMI)to themselves and other equipment.Strictly speaking,as long as two or more components are placed in the same electromagnetic environment,electromagnetic interference will occur.Therefore,the EMC/EMI problems of electrical and electronic equipment are becoming increasingly acute,and many scientific researchers have studied them one after another.Among them,the chassis electromagnetic shielding is a very intuitive and effective method to prevent electromagnetic radiation.Based on theoretical analysis and numerical calculation,this paper analyzes the shielding effectiveness of complex shielding boxes under different conditions through three-dimensional electromagnetic simulation.The research is as follows:(1)Conduct theoretical research on guided electromagnetic waves,take a rectangular waveguide as an example to perform numerical analysis to obtain its field quantity expression,and perform modeling and simulation according to the national standard waveguide size GB11450.2-89(BJ100)to obtain a rectangular waveguide.The characteristics of the different modes of the waveguide and the propagation characteristics of electromagnetic waves in the waveguide.In addition,based on the resonant cavity theory,the reasons for the electromagnetic radiation resonance of the rectangular cavity and the PCB board are studied,the mechanism and conditions of the resonance generation are clarified,and the electromagnetic resonance phenomenon is improved through simulation.(2)The traditional chassis model based on Robinson theory,externally connect waveguides to the display window or vent of the chassis,establish an equivalent circuit model and perform numerical analysis,and then use ANSYS for modeling and simulation to verify the shielding effectiveness of the improved model Better,at the same time,the improved model has been subjected to multiple sets of comparative simulations to obtain the influence of resonance and electromagnetic leakage on the shielding of the chassis,which has a certain guiding significance for the structural design of the chassis.(3)Co-simulation of PCB board and chassis is used for electromagnetic compatibility simulation analysis.First,analyze the PCB board,and then dynamically link the electromagnetic simulation three-dimensional model(Dynamic Link)to Circuit design for field-circuit co-simulation.Finally,conduct a collaborative simulation analysis on the PCB board and the chassis to view the overall system indicators.