New Theoretical Expressions for Predicting Shielding Effectiveness for the Plane Shield Case

The problem of the electromagnetic shielding effectiveness of a thin, plane metal sheet of infinite extent on the electromagnetic field generated by a circular loop field source with uniform current I is solved by application of the quasi-near and near field approximations to the exact integral expressions. The results are shown to be in close agreement with experimental data as well as numerical integration results. Also, they are similar to the results obtained from the plane wave shielding theory of Schelkunoff.