Pre-compliance EMC measurements for MRO equipment

The establishment of Australia´s newest radio astronomy observatory, the Murchison Radio-astronomy Observatory (MRO), in the remote Mid West region of Western Australia offers very low ambient radio frequency interference (RFI) levels and is an ideal location for high sensitivity large collecting aperture instrumentation operating between 70MHz and 25GHz. Unlike previous radio astronomy (RA) facilities, all plant, electrical, electronic equipment and subsystems are required to meet, or better, rigorous MIL-STD 461F EMC standards for radiated emissions prior to deployment at the site. The site is regarded as a common infrastructure platform for several users and systems with disparate operational frequencies and antenna technologies distributed over several kilometres. A common requirement is radio quietness. A main building facility housing the MRO digital signal processing systems has achieved a shielding effectiveness (SE) design goal in excess of 160dB at 5GHz. This paper discusses the test protocol and measurement apparatus used at the CSIRO for equipment EMC compliance in the ASKAP project.