Shielding and energy transfer of transient electromagnetic fields

For the time-harmonic electromagnetic fields the shielding effectiveness of conducting and permeable materials is characterized by the relation of the field amplitudes or their quadratures arising at chosen locations in the absence of the electromagnetic shield to the ones arising in the presence of it. In theoretical treatises homogeneous electric or magnetic fields, plane fields of parallel conductors, homogeneous plane waves, or fields of elementary electromagnetic radiating sources are considered. This work presents a study of the transient field excited by a current loop i(t) of arbitrary time dependence and arbitrary contour in the presence of a plane, conducting, and permeable screen of finite thickness. The shielding effectiveness of the screen is characterized by the time dependence of the electromagnetic energy transfer into the shielded area caused by switched or pulsed sources.