Electromagnetic interference (EMI) shielding of apertures in electro-optical (EO) systems can be accomplished generally by transparent electrically conductive (EC) coatings, wire meshes or opaque EC coatings patterned to form meshes. The shielding effectiveness (SE) of these methods are studied both analytically and experimentally. The shielding due to both absorption and reflection as a function of frequency was evaluated. EO systems often use aperture windows made of dielectric or semiconductive material which transmit in the optical waveband(s) of interest. The effect of the substrate material on the SE of the both deposited transparent EC coatings and on opaque mesh patterned EC coatings is examined. The broadband shielding benefits of using aperture windows with EC coatings deposited on semiconductive window substrates is proposed.
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