Research Of Electromagnetic Shielding Performance On Chassis

With the increasing update of electronic products and the operating frequency of digitalsystems, electromagnetic compatibility becomes more prominent. As the focus in the field ofelectromagnetic compatibility, electromagnetic shielding gets more attention of scholars.Electromagnetic shielding is a method of electromagnetic interference control, it can blockthe transmission of electromagnetic interference in space, that is blocking the propagationpath of the harmful electromagnetic waves in the space. In practice, electromagnetic shieldingcan deal with a lot of electromagnetic interference problems, the biggest advantage is that theelectromagnetic shielding either can control the intensity of electromagnetic radiation withinthe safe range, at the same time they do not need to re-design the circuit. Therefore, in anumber of measures to reduce the harmful electromagnetic waves, electromagnetic shieldingoccupies a very important position.In the modern electronic industry, chassis electromagnetic shield is a common means toensure the normal working of the electronic components, it is also the final barrier to preventthe radiation emitted. In order to solve the problem of the endless variety of electromagneticcompatibility, in the initial stage of the chassis structure design, the consideration is veryimportant for the shielding performance.Chassis electromagnetic shielding is a very effective way to prevent electromagneticinterference, in addition to its limitations, we pay more attention to the problem of how toimprove its electromagnetic shielding performance. The actual surface of the shielding bodyemerges a certain roughness and different degrees of rough surface on the incidentelectromagnetic wave produces different strength of the scattered field for processing reasons.Therefore, in addition to considering shielding materials, holes, gaps, shielding platethickness, surface roughness would become another factor affecting the chassiselectromagnetic shielding performance is the focus of this study. To solve the above problem,we have studied the impact of surface roughness of its electromagnetic shielding performancechassis based on the theory of electromagnetic scattering.The electromagnetic theory and numerical methods for shielding analysis have beenproposed, and then we have presented the basic terminology of the surface roughness andassessment parameters, which pointed out the restriction of traditional assessment parameters.Simulation have been used to calculate the analysis its inadequacies. Study rough surface fractal characteristics of several surface roughness modeling methods, and we established thefractal rough surface model with better performance. Based on fractal rough surface model weused the method of moments calculation of one-dimensional ideal conductor rough surfaceelectromagnetic scattering and total scattering power and bistatic scattering coefficient ofparsing the form, and then we studied of the impact of the various parameters of the scatteredfield, on this basis of the rough surface of the shield shielding effectiveness in a single plane.Finally, we analyzed the influence of the chassis inner surface roughness of its shieldingeffect. According to the conclusion,: the smaller the surface roughness is, the worse the effectof reflective shield and absorb shield are, and the greater scattering coefficient near the mirrorreflection direction is. It is easy to interfere with the electronic equipment inside the enclosure;The larger the surface roughness is, the greater the scattering range is, the smaller scatteringcoefficient on the mirror reflection direction is and the shielding effect in the chassis innersurface roughness is relatively small.