Report on an inter-laboratory comparison of EMC antenna factors on antennas used above 1 GHz

An inter-laboratory comparison of greater than 1 GHz antenna calibration was started in September 2002, managed by Hewlett-Packard. This study was started because data from six different calibrations of a horn antenna varied more than expected by National Physical Laboratory (UK). The variance was also more than that obtained in the very well defined and controlled study of an X-Band Horn antenna (Stubenrauch, 1996) study piloted by NIST. Initially three antennas were being circulated by ETS-Lindgren, Liberty Labs and NIST (US), Schwarzbeck, Rolf Heine, Rohde-Schwarz and CONFORMITAS (Germany), Austrian Research Center (Austria), NPL and Communications Research Laboratory (Japan). Four laboratories have completed the calibration. Preliminary results show worst case deviations between laboratories to be greater than 5dB. Some of variations appear to be abnormal spikes that do not follow the normally expected antenna trend and need to get resolved before supplying factors to a user/customer. One of the laboratories provided antenna pattern data that supports findings by Michael D, Foegelle (2002) and Christian Burns et al. (2003).