We propose an approximate analytical model for magnetic field penetration through a circular aperture on a perfectly conducting plate. The magnetic field source is a circular loop current placed parallel to the plate and coaxial with the aperture. It is shown that the aperture is equivalent to a magnetic quadrupole normal to the plate when the field point is far from the aperture. The model is validated using numerical simulations and a minor disagreement with experimental data is explained.

中文翻译：

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低频磁场穿过完美导电板上圆孔的解析模型


我们提出了一个通过完美导电板上的圆形孔径的磁场穿透的近似分析模型。磁场源是平行于板且与孔径同轴放置的环形回路电流。结果表明，当场点远离孔径时，孔径相当于垂直于板的磁四极子。该模型通过数值模拟进行了验证，并解释了与实验数据的微小差异。