Estimation of standards compliance uncertainty for radiated emission measurement in the pt program

VLAC, a Japanese laboratory accreditation body mainly in the field of EMC testing, has organized PT (Proficiency Testing) program of EMI measurement six times since 2005. The program has been performed with the type of inter-laboratory comparison by circulating an artifact. Based on the evaluation result of programs, the SCU (standards compliance uncertainty) of radiated emission measurement was estimated from the group interval of the collected data. Each test site carried out the measurement of radiated electromagnetic interference from the artifact under the conditions specified in the program including the use of the accompanying VHF LISN (Line Impedance Stabilization Network) to specify the common mode impedance of AC power supply of each participated test site. This paper discusses the calculation value of SCU which resulted in no greater than 6.9dB if EUT (Equipment under Test) has a simple operating condition and makes a simple test arrangement, and if the terminating condition of AC mains power supply is specified with using a stabilization device such as VHF-LISN.