Experimental investigation on the EM signal attenuation characteristics of a single-layer metal shielded laboratory

This paper describes the shielding behavior of a laboratory shielded with copper sheets from electromagnetic waves present in the surrounding neighborhood. The laboratory was constructed for measuring high frequency signals generated from partial discharge (PD) of specimen samples under test. The purpose of the shielded laboratory is to attenuate the incoming electromagnetic waves, primarily the communication signals, inside the laboratory and to reduce the external electromagnetic interference to such a level that it would not interfere with the PD signals. To study the attenuation behavior of the laboratory with respect to electromagnetic waves, the testing method adopted was the conversion of electromagnetic wave to an acceptable output level that is in proportion to the amplitude of the incident electromagnetic signal. A handheld measuring unit was made and the resulting voltages were measured at different parts of the shielded laboratory. The results presented in this paper reflect (1) the attenuation behavior of the laboratory with respect to incident electromagnetic waves and (2) the nature of variation of electromagnetic wave attenuation inside the shielded laboratory