屏蔽效能数值仿真中机箱谐振特性建模与分析

Numerical modeling and analysis of enclosure resonance characteristics in its shielding effectiveness simulation

对含有大量孔、缝和复杂元器件的机箱进行屏蔽效能仿真是难以实现的,主要面临精细结构建模困难、材料参数无法确定、离散网格数量巨大和计算迭代收敛困难等问题.因此,不少文献还主要是对含有简单孔、缝的空机箱进行数值仿真和屏效分析.而空机箱的谐振特性与含有大量元器件的实际机箱的谐振特性相差甚远,使得屏效的仿真和实测结果无法匹配.提出引入背景传输损耗以等效模拟机箱内部元器件对电磁能量的吸收,基于混响室Q值测试理论建立背景传输损耗和机箱吸收损耗的联系并确定背景媒质的参数设置.新的分析方法准确模拟了真实机箱的谐振特性,同时可减小数值仿真对材料参数和网格尺寸的过度依赖,极大地提高了仿真效率,仿真与实测结果可相互匹配并且吻合良好.

It is very difficult to realize the shielding effectiveness（SE）simulation of complex enclosures consisting of quantity vents,slots and inner components.Numerical simulation always faces the challenges from fine structure modeling,uncertainty of material parameters,huge number of grids and slow convergence of calculation.Therefore,many literatures just refer to the SE simulation of empty enclosures with simple holes or slots.However,the resonance characteristics between an empty enclosure and an enclosure crammed with components are completely different,which inevitably lead to the mismatch of simulation and experimental results.This paper introduces the background transmission loss to simulate the electromagnetic energy absorption in enclosures by internal components.A link between background transmission loss and component absorption loss is established based on the Quality Factor（Qfactor）testing theory in reverberation chambers,and finally it determines the parameter setting of background in return.Proposed modeling methods accurately describe the resonance characteristics inreal enclosures and reduce the dependence of numerical simulation on material parameters and mesh grids,greatly enhance the simulation efficiency,and consequently result in good matches of simulation and experimental results.