Influence of Extension Lines on Electromagnetic Shielding Effects of the Wire-Mesh Frame Structure

Frequencies of electromagnetic noise radiated from electrical equipment are almost always clock frequencies and their harmonics. Therefore simple electromagnetic noise countermeasures for specific frequencies are needed. Simple electromagnetic shielding methods using a wire-mesh frame structure made of several straight conductors and a fine wire-mesh plane attached to one side are described and the shielding effects studied both experimentally and analytically. The shielding effects of this structure were found to exceed 20 dB at the resonance frequencies. The shielding effect of this wire-mesh frame structure on actual telecommunication equipment, including extension lines, was clarified by measurement and calculation. The shielding effect is increased when the extension lines inside the wire-mesh frame structure are shielded by conducting tape.