Usability of absorber-lined shielded environment for low-frequency magnetic field measurement

Abstract

This paper discusses the results of a study the authors conducted to clarify the usability of an absorber-lined shielded environment (ALSE) as a 150 kHz and lower frequency magnetic field measurement environment using the mirror image method. The magnetic field strength at a measurement point obtained from the mirror image method almost agreed with the measured value and the value obtained by a 3D electromagnetic field analysis, confirming that the mirror image method is effective for estimating the magnetic field strength at a specific measurement point. It was also confirmed that the usability of ALSE for magnetic field measurement depends largely on the distance of the magnetic field source and measurement point from the six walls of the ALSE. The study confirmed that, if the distance between the magnetic field source and measurement point is 1 m or less and they are 1 m or more from the ALSE's wall surfaces, the value measured in an ALSE that can be used to measure electromagnetic emissions from components does not differ by more than 3 dB from the value measured at an outdoor test site (OTS) for automobile evaluation.