Intercomparison study of dipole antenna for EMI testing

Open Area Test Site (OATS) is popular in EMI testing of commercial products. The EMI instrumentation along with other sensors contribute effectively to obtain EMI data to compare against the EMC standards. The measurement errors accumulated by every instrument, sensor and OATS may render the equipment under test (EUT) with doubtful results. Globally these variations are observed and, through intercomparison studies, the variables are identified for confidence in EMI testing. In northern India two 3 m OATS at New Delhi and Mohali are used for EMI testing of various products. To increase confidence in the sensors, namely the dipole antenna, an intercomparison test was carried out using the standard site method. The maximum variation observed was the order of 0.7 dB on the seven spot frequencies except 1000 MHz where, the variation was 1.25 dB. In this paper the methodology of intercomparison of dipole antenna calibration and analysis of results observed at Delhi and Mohali are described. The result indicates the variation of data at different sites which are crucial while evaluating the critical system of close tolerance/accuracy limits