EMC antenna calibration sites (30 MHz to 1 GHz)-putting theory into practice

The CE directives on EMC which came into effect on 1st January 1996, have led to an increasing awareness of the uncertainty of measurements in radiated emissions. EMC antenna calibration, and open area test site (OATS) validation, are two of the topics which now feature prominently in virtually any discussion on the subject of EMC. The South African Bureau of Standards constructed a new OATS in 1993, and the validation of this site was followed by a number of antenna intercomparison exercises. An application for accreditation by the National Laboratory Accreditation Service (NLA) was submitted early in 1998, and the assessment took place on 15 April 1998. This paper will deal primarily with the process which was followed to put the theoretical concepts behind OATS validation and antenna calibration into practice. A major factor which has contributed to the successful completion of this exercise was the fact that all measurements were traceable to national standards. This allowed direct comparison of all the measurement results by maintaining constant reference values.