Anechoic Room vs Open Area Test Site: A Case for EMC Study

An open area test site (OATS) is the main choice of electromagnetic compatibility test facilities (TF) presently recommended by EMC testing standards and regulations throughout the world. However, the OATS inherent limitations (e.g., RF ambients) stimulate the development of alternative TFs, of which the absorber lined shielded room (AR) appears to be the most promising one. This paper presents a discussion of the AR performance in comparison with the OATS. Theoretical and experimental data are presented on the effects of the TF design, chamber size and absorber properties, as well as the EMI source and field probe positioning on radiated emissions test results and antenna pattern measurements. A concept of absorber lined open area test site is introduced.