Differences Between NSA 94-106 and IEEE Std. 299 Setups for Low-Frequency Magnetic Shielding Effectiveness Characterization: A Study Using Numerical Simulations

This letter employs simulation findings to demonstrate the practical reasons why the low-frequency magnetic shielding effectiveness is different when characterized using two parallel loops (NSA 94-106) or two coplanar loops (IEEE Std. 299). It is shown how the change in the loop’s radius impacts the shielding effectiveness for the NSA 94-106 setup rather than for the IEEE 299 one. The observation is rooted in the difference of the wave impedance for both scenarios. Additionally, the letter elucidates the reason behind the wave impedance difference.