Low-Frequency Magnetic Shielding of Planar Screens: Effects of Loop Radius and Loop-to-Loop Distance

For the magnetic shielding configuration of both emitting and receiving loops placed coaxially on either side of a planar screen, we investigate the effects of loop radius and loop-to-loop distance on shielding effectiveness by numerically solving the accurate integral expression. The results are in good agreement with finite element simulations and experimental results. Simple and reliable approximate formulas are also proposed for pure conductive screens and pure magnetic screens, respectively. It is shown that the effects are obvious when the loop-to-loop distance is smaller than the loop radius. Also, conductive screens and magnetic screens exhibit opposite and competing shielding effectiveness evolution behaviors. In addition, in the case of conductive screens with a smaller receiving loop compared to the emitting loop, the shielded loop-to-loop mutual inductance does not always decrease with the increase of the loop-to-loop distance but peaks at a distance between the screen thickness and half of the emitting loop radius.