一种近场屏蔽的基本模型及试验验证

A Fundamental Model for Near-field Shielding and Verification Test

随着对屏蔽理论的深入研究,屏蔽体的基本模型也在不断地发展。经典的Schelkunoff屏蔽定量测试方法是根据传输线理论来定量描述屏蔽效能的一种常用方法,但在实际应用中,研究者往往对其对于电场和磁场屏蔽的不同性产生质疑。通过对屏蔽效能描述方法的分析及对电场和磁场偶极子模型的研究和计算,建立了一种近场屏蔽的基本模型,利用该模型可清晰地描述屏蔽设备对外辐射发射与内部干扰源的对外辐射发射的依存关系,得出屏蔽体在远场对磁场和电场可进行同等衰减,而在近场对于低频磁场抑制更加困难的结论,并通过试验进行了验证,证明了Schelkunoff屏蔽分析方法在远场应用的正确性。

The fundamental models for shielding enclosure are developing with constant researches on the shielding theo- ry. The classic approach for the quantitative treatment is that presented by Schelkunoff approach by employed transmission line equations in shielding analysis. But in practical application, the difference between electric field and magnetic field shiel- ding is often questioned. Through the analysis of the method of shielding effectiveness and the research, and the calculation of electric and magnetic dipole model, a basic model for near field shielding could illustrate the interdependence of emissions from the shielded enclosure and the basic source of emissions within the enclosure. The conclusion shows that the magnetic and electric field can be equally attenuated in the far field, but in the near field shielding the magnetic field is more difficult. And a verification test is designed to verify the conclusion of the basic model, and prove the correctness of Schelkunoff ap- proach to shielding analysis which is often questioned.