Study of conditions for maximum efficiency of perforated electromagnetic screens

Abstract

The basic relations for calculating the efficiency of shielding electromagnetic fields in the far zone by metal
materials and structures with round and rectangular holes are determined. The reflection of electromagnetic waves from the perforated surface is taken into account. It is shown that at the holes with a finite wall thickness, frequency bands of transparency of the
structure may occur due to resonant phenomena. This follows from the theory of waveguides. The thickness of the screen wall is
considered to be a waveguide of this length. The dependence of the shielding efficiency on the frequency of the shielded electromagnetic field is investigated. The presence of frequency bands of screen transparency at frequencies lower than the cutoff frequencies for these geometrical openings is established. The relations for calculating the contribution to the shielding of continuous
sections of a perforated structure are obtained. The relations take into account the electrophysical properties of the shield material,
the frequency of the shielded electromagnetic field, and the depth of penetration into the material. Taking into account the empirical
nature of these relations and possible additional factors of possible changes in shielding properties (the influence of regularly spaced
ventilation holes), it is advisable to test the designed structures in real operating conditions. A promising area of research is to
improve the shape of the screens by lengthening the depth of the holes.