Antenna calibration in emc semi-anechoic chamber using standard antenna method (sam) and standard site method (ssm)

Abstract

Electromagnetic Compatibility (EMC) engineers should self-check the antenna’s condition and parameters, including Antenna Factor (AF) and Gain, continuously, by calibrating the antenna. Therefore, several analyses have been done to compare between SAM and SSM in EMC testing lab. Based on the analysis, the antenna to be used inside a 3 m semi-anechoic chamber need to be positioned 1.5 m above the ground plane to avoid the reflection. The Antenna Factor (AF) results show a good agreement with manufacturer data. SAM is recommended as a calibration method in the semi-anechoic chamber because the percentage error is 5% which is lower compared with SSM (18%). This is due to the site imperfection in the EMC lab. The uncertainty for the EMC lab is up to ±4 dB, compared to the calibration test site where allowed uncertainty is ±1 dB. Therefore, an absorber needs to be placed between two antennas. In addition, the phase center of the reference antenna needs to take into consideration for highly accurate AF.