EMC prediction model of a single wire transmission line crossing a circular aperture in a planar screen

The structure composed by a wire running above a ground plane and passing through an aperture in a semi-infinite metallic screen is analyzed from an electromagnetic point of view. We assume that the distance between the wire and the ground plane is sufficiently greater with respect to the aperture dimensions and that the latter are small in comparison with the free-space wavelength. A very accurate low frequency solution is obtained by representing the field quantities in a suitable spectral domain and by treating the wire current as a filament current. A transmission line model of the structure, based on the scattering parameter representation for both internal and external excitation, is derived. Then, by use of such a model, analytical expressions for an insertion loss and a signal-to-noise ratio (SNR) are obtained in order to assess the electromagnetic compatibility of the structure.