Analysis for electromagnetic leakage through a plane shield with an arbitrarily-oriented dipole source

The shielding performance of an infinitely large plane shield of uniform and isotropic material is investigated theoretically. An infinitesimal electric or magnetic dipole is taken for a radiating source assuming that its location and orientation are arbitrary. To correctly use the conventional transmission theory for near-field shielding problems, a plane wave expansion is performed to describe all the fields involved. As a result, general formulae for the leakage fields are derived in an integral form for every configuration of the source and observation points. They are expressed in terms of the transmission coefficients of the evanescent waves and the ordinary plane waves. The validity of the formulae is verified by comparison of the computational results with the previously reported experimental results. It is found that the formulae can be applied to a very wide range of frequencies and distances