Electromagnetic shielding of highly transparent inductive mesh

This paper studies the influencing factors on the electromagnetic shielding of an inductive metallic mesh when the infrared transmission reduction of optical window caused by the mesh is less than 5%.The infrared transmission formulas of the inductive mesh are summarized,then,the electromagnetic field integral equation for the periodic structure of metallic mesh is built based on Galerkin's method in the spectral domain.The transmission and reflection coefficients are derived by the Moment of Method(MOM).After that,the electromagnetic shield effectiveness of the mesh is calculated and the effects of different line widths,periods,substrate materials,substrate thicknesses on the electromagnetic shielding of the transparent conductive optical window(with metallic mesh) are calculated and analyzed.Finally,metallic mesh samples with a line width of 12 μm,a period of 360 μm×360 μm and the surface resistance of 13 Ω,25 Ω are fabricated on a ZnS substrate by the laser direct writing figure,vacuum coating,et al..The electromagnetic shield effectiveness from 2 GHz to 18 GHz is tested by a free space method.Results indicate that the average electromagnetic shield effectiveness is more than 20 dB when the infrared transmission reduction caused by the metallic mesh is less than 2% in 8-10 μm.Experiments indicate that the optical and electrical performance of metallic mesh film is inconsistent.The main solution method is to select a thinner line width and smaller period and to reduce the surface resistance value of the mesh as low as possible at the same time.