多层金属板低频磁屏蔽效能的理论模型与特性分析

针对多层无限大金属板对圆环线圈磁屏蔽问题,通过分离变量法严格求解麦克斯韦方程组,推出多层板磁屏蔽效能的解析公式,并对其进行编程计算。将多层板屏蔽效能计算公式取特殊值简化成单层板,得到的结果与Moser单层板屏蔽效能公式一致。分析多层板位置、多层板顺序以及板间空隙对屏蔽效能的影响。结果表明,当金属板的厚度、顺序以及圆环线圈和观测点位置不变时,屏蔽效能与多层板位置无关。当圆环线圈、金属板及观测点位置不变时,颠倒板的顺序不影响屏蔽效能。频率低于10 kHz时多层板空隙对屏蔽效能的影响较小,频率高于10 kHz时多层板屏蔽效能随空隙的增大而增大。

Theoretical Model and Characteristic Analysis of Low-frequency Magnetic Shielding Effectiveness of Multilayer Metal Plates

In this paper, for the magnetic shielding problem of the multilayer infinite metal plates to the circular antenna, the Maxwell equations are solved strictly by the method of separating variables. Finally, the analytical formula of the magnetic shielding effectiveness of the multilayer plates is derived and programmed.The calculation formula of shielding effectiveness of multilayer metal plates is simplified to single-layer metal plate, and the result is consistent with Moser''s formula of shielding effectiveness of single-layer metal plate. The influence of the position, the order and the gap between the multilayer plates on the shielding effectiveness is analyzed. The results show that the shielding effectiveness is independent of the position of the multilayer plates when the thickness and order of the metal plate, the position of the circular antenna and the observation point are unchanged. When the position of circular antenna, metal plate and observation point is constant, reversing the order of the multilayer plates does not affect the shielding effectiveness. When the frequency is lower than 10 kHz, the effect of the gap between the multilayer plates on the shielding effectiveness is small. When the frequency is higher than 10 kHz, the larger the gap between the metal plates, the greater the shielding effectiveness.