Shielding effectiveness prediction in MIL-STD 285 loop source configuration

An analytical formulation is presented for the evaluation of performance of a planar shield in the low-frequency, low-impedance antenna configuration described by MIL-STD 285 and IEEE Std. 299. The magnetic field computed in various shield configurations by means of the proposed closed-form expressions is presented. The proposed procedure allows the evaluation of the shielding effectiveness exactly. The effects of the finite size of both the transmitting and receiving antenna are taken into account accurately and highlighted. Finally, the exact solution is compared with that deriving from the use of the so-called transmission line (TL) approximation, in various conditions.