中文摘要：

基于扩展的等效电路方法，建立了电偶极子和磁偶极子天线近场照射下开孔矩形腔体电磁屏蔽效能计算的近似解析模型，计算分析了场源一腔体距离对电场和磁场屏蔽效能的影响规律．结果表明在近场区，屏蔽效能随场源一腔体距离的减小而明显减小，近场屏蔽效能小于远场屏蔽效能．基于Bethe小孔耦合理论，得出了描述近场和远场屏蔽效能关系的解析公式，并用该公式检验了等效电路方法计算结果的可信性．

英文摘要：

The shielding effectiveness of an apertured rectangular cavity against the near-field waves of both electric and magnetic dipoles is investigated theoretically by using an extended equivalent circuit method. Both electric and magnetic shielding effectivenesses are calculated as functions of distance between the dipoles and the enclosure. It is shown that the near-field shielding effectiveness is lower than the far-field （plane-wave） shielding effectiveness. Also, in the near-field region, the shielding effectiveness will reduce obviously with the decrease of the source-to-enclosure distance. Based on Bethe＇s small aperture coupling theory, analytical formulas are presented to describe the quantitative relation between the near-field and the far-field shielding effectivenesses. It is shown that the results from equivalent circuit method are in good agreement with the relation obtained from the Bethe＇s theory.