Ricerc@Sapienza

The magnetic shielding effectiveness of a planar metallic screen of infinite extent against a circular loop field source is analytically evaluated in a new closed-form formula under the thin sheet and small-loop approximations. The results obtained with the proposed formulation are compared with the exact ones derived numerically and with those obtained through classical approximate formulations.

The classical electromagnetic problem represented by a small loop axially parallel to a thin conductive planar shield of infinite extent is addressed in the time domain. The problem is solved analytically through a modified Cagniard-de Hoop approach and numerically through the double inverse Hankel/Fourier transform. Although some approximations are made, the analytical method is the most useful in predicting the main time-domain shielding characteristics.

The problem of the shielding evaluation of an infinitesimally thin perfectly conducting circular disk against a vertical magnetic dipole is here addressed. The problem is reduced to a set of dual integral equations and solved in an exact form through the application of the Galerkin method in the Hankel transform domain. It is shown that a second-kind Fredholm infinite matrix-operator equation can be obtained by selecting a complete set of orthogonal eigenfunctions of the static part of the integral operator as expansion basis.

The electromagnetic problem of calculating the pulsed radiation from a horizontal magnetic dipole in the presence of a planar thin conductive screen is solved analytically in the time domain via a modified Cagniard-de Hoop approach. The components of the relevant time-domain electric and magnetic dyadic Green's functions are expressed by simple one-dimensional integrals over a finite integration domain. Expressions for the transient electromagnetic fields can thus easily be obtained and numerical results are provided that illustrate the main time-domain shielding characteristics.

The problem of evaluating the shielding effectiveness of a thin metallic circular disk with finite conductivity against an axially symmetric vertical magnetic dipole is addressed. First, the thin metallic disk is modeled through an appropriate boundary condition, and then, as for the perfectly conducting counterpart, the problem is reduced to a set of dual integral equations which are solved in an exact form through the application of the Galerkin method in the Hankel transform domain.