A statistical description of field uniformity and its effect on the measured immunity of equipment under test

During radiated susceptibility measurements the equipment under test (EUT) is exposed to field strengths of up to several volts per metre. These high field levels cannot be radiated in unbounded test environments, such as open-area test sites, and so a variety of screened room and absorber lined chamber environments are used instead. The screened rooms form resonant cavities and absorber material is not very efficient, in the frequency range from 30-200 MHz, so that the field that illuminates EUTs in these environments is far from uniform. The objective of the project was to measure the field uniformity within typical radiated susceptibility testing environments and to assess its effect on the repeatability of measurements performed within them