Refined Study On The Magnetic Shielding Effectiveness Of Metal Plate

With the rapid development of science and technology,electronic equipment and electrical devices are widely used in various fields such as industry,transportation,power,and people are living in the complex electromagnetic environment.Information errors and control failures may be caused when the electrical equipment and communication equipment be in a strong electromagnetic environment.Electromagnetic shielding is one of the most effective and basic ways to weaken the electromagnetic field.The shielding ability of electromagnetic shielding to electromagnetic fields can be expressed in terms of electromagnetic shielding effectiveness.Low-frequency magnetic shielding is a difficult point in electromagnetic shielding.The calculation and characteristic analysis of the low-frequency magnetic shielding effectiveness of metal plates have important practical significance.In this paper,the expression of the electromagnetic field of the loop antenna with the shield plate in free space is verified.Based on this,the shielding effectiveness formula is obtained,and the influence of different parameters on the magnetic shielding of a single-layer board is analyzed.Based on the current distribution characteristics of the metal plate,a method for determining the critical size of the magnetic shielding of the metal plate is proposed,and its reliability is verified through simulation and experiments.The influence of different factors on the edge effect of the metal plate is further analyzed.Based on the expression of the electromagnetic field of a single-layer shield board,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 influence of different factors on the shielding effectiveness of the multi-layer shield is analyzed.Based on the continuous boundary conditions of the tangential component of the electromagnetic field,the shielding effectiveness formula of multilayer metal plates when plane waves are incident at normal incidence is derived.Based on the transmission line analogy method,the vacuum wave impedance part of the formula was replaced with the near-field wave impedance to obtain a simpler formula for the magnetic shielding effectiveness of a metal plate.