Electromagnetic radiation screening device for electrical apparatus and cables

摘要

Screening for electrical apparatus and cables against EM radiation uses two conducting sleeves (1,2) sandwiching a dielectric layer (3) to form a capacitor. A potential difference exists across the sleeves. The inner sleeve is at earth potential. The outer potential is chosen so that the field strength of the generated electric field in the dielectric is greater than the magnitude of the electric field components of the interfering EM radiation. The outer sleeve is a fine steel mesh or a thin foil. The inner sleeve is a foil exhibiting negligible resistance for high frequencies, such as aluminium, copper, silver, gold or copper-plated aluminium. There is a resistance between the voltage source and the outer sleeve.