Generating electromagnetic standard fields for legal metrology purposes

In order to provide calibration services for radio-frequency (RF) field measuring equipment for safety protection purposes and to perform electromagnetic field susceptibility tests as part of the legally required pattern approval procedures for electronic measuring instruments, improved field generating equipment has been installed. Traceability to the German national standard RF-power measurement device is described, and an estimation of its overall uncertainty is given. It is concluded that only a few field generating devices meet the basic requirements of a test laboratory, i.e., very broad frequency range from DC through some GHz, constant gain vs. frequency, homogeneous field distribution, spacious test volume, and shielding against the environment. The minimum total absolute uncertainty of field generation neglecting the effects of the equipment under test for frequencies up to 2 GHz seems to be about 3 dB; reproducibility might be as low as 0.5 dB.<>