Impact of Semi-Anechoic Chambers on Magnetic Field Measurements for Frequencies up to 30 MHz

Over the past years, development of wireless power transfer systems for battery electric vehicles increased noticeably. In order to evaluate these systems regarding their radiated magnetic field emissions in EMC laboratories, it is essential that the measurement results of different test sites are comparable to each other. As absorbers in semi-anechoic chambers are not typically designed for frequencies below 30 MHz, the impact of the test environment onto the measurement results needs to be investigated. In this paper, measurements in the frequency band from 9 kHz to 30 MHz are carried out in a large semi-anechoic chamber suited for test distances of up to 10 m. The measurements are compared to numerical simulation results and a simple simulation model is proposed to estimate the influence of a test site onto measurement results.