Analytical Magnetic Shielding Calculation of a Slotted Conducting Plate Between Coplanar Circular Loops

This article proposes an analytic solution to calculate the magnetic shielding effectiveness (MSE) of a slotted conducting plate between coplanar circular loop antennas at a low-frequency range below 20 MHz. Mutual inductances of coplanar circular loops in the presence and absence of the slotted conducting plate are analytically derived by using the representation of an equivalent current loop and the analytic formulas presented in recent literature. Then, the MSE is defined by a ratio of two analytic mutual inductances. For the accuracy validation, the design of experiments (DOE) is performed using the difference between MSEs of the proposed solution and the numerical simulation in terms of the sizes of loop antenna and slot. Good agreement is achieved with an average error of 1.3 dB for the shielding measurement configuration of IEEE-Std-299. In addition, the proposed analytic solution requires negligible computation time.