Electromagnetic shielding by thin periodic structures and the Faraday cage effect
Provides theoretical understanding of the Faraday cage effect for electromagnetic shielding, relevant to engineers and physicists designing shielding structures.
The paper studies electromagnetic wave scattering by thin periodic layers of perfectly conducting obstacles, deriving homogenized interface conditions for three configurations. It shows that full shielding (Faraday cage effect) occurs only for a wire mesh, not for discrete obstacles or parallel wires.
In this note we consider the scattering of electromagnetic waves (governed by the time-harmonic Maxwell equations) by a thin periodic layer of perfectly conducting obstacles. The size of the obstacles and the distance between neighbouring obstacles are of the same small order of magnitude $δ$, $δ$ being small. By deriving homogenized interface conditions for three model configurations, namely (i) discrete obstacles, (ii) parallel wires, (iii) a wire mesh, we show that the limiting behaviour as $δ\to0$ depends strongly on the topology of the periodic layer, with full shielding (the so-called "Faraday cage effect") occurring only in the case of a wire mesh.