CISPR standard for calibration of EMC antennas

Electronic products placed on the market must exhibit radiated emissions below those levels specified in applicable international standards. Low uncertainty measurement of these emissions requires antennas calibrated with low uncertainties. This paper presents methods from the draft standard CISPR 16-1-6 for measuring the free-space antenna factor of antennas from 30 MHz to 18 GHz. Included is the measurement of antenna factors at various heights above a ground plane, a situation where the measured antenna factor can vary typically by ± 2 dB. Also included numerical modelling of wire antennas which is used to estimate the uncertainty components in radiated emissions measurements that arise from the properties of antennas, such as mutual coupling, radiation patterns and phase centres. The emphasis is on calibration methods that are both straightforward and economical.