Magnetic Shielding of Planar Metallic Screens: A New Analytical Closed-Form Solution

The magnetic shielding effectiveness of a planar metallic screen of infinite extent against a circular loop field source is analytically evaluated in a new closed-form formula under the thin sheet and small-loop approximations. The results obtained with the proposed formulation are compared with the exact ones derived numerically and with those obtained through classical approximate formulations. It is thus shown that the proposed formula is the most accurate closed-form expression proposed so far and the frequency range where a percentage relative error less than 1% is obtained is clearly identified.