Magnetic-field transmission through a circular aperture in a magneto-conductive screen. Identification of aperture penetration and field diffusion contributions

The magnetic field transmitted through a circular aperture in an infinite magneto-conductive planar screen with finite thickness is studied, considering as a source a circular electric current loop coaxial with the aperture. The field source consists of a circular electric current loop coaxial with the aperture. First, the finite thickness of the aperture is taken into account through suitable generalized boundary conditions. Next, a pair of dual integral equations are obtained whose solutions are obtained by means of an expansion of the unknowns in Neumann series of Bessel functions combined with a Galerkin method of moments. Such solutions furnish equivalent electric and magnetic spectral current densities fromwhich all the field components can easily be obtained. The proposed formulation allows for clearly distinguishing the contributions to the total transmitted field coming from the diffusion in the magneto-conductive screen and the penetration through the aperture, thus gaining physical insight into the transmission mechanism. Numerical results are presented and compared with those obtained through commercial software to show the accuracy and the efficiency of the proposed formulation.