Automation of radiated emission measurements with an ultra-fast time-domain EMI measurement system

Traditionally emission measurements are performed in frequency domain and take a long time for a single scan. Pre- and final scans are performed to reduce the time for the characterization of the device under test. Emission measurements in time-domain can reduce the measurement time for a single scan up to a factor of 4000. In this paper novel test procedures for automated radiated emission measurements are presented. Based on an initial scan the minimum dwell time required by the instationarity of the emission of the device under test is determined. For a minimum dwell time higher than the steady state time of the detector mode a full maximization is performed, for a minimum dwell time smaller than the steady state time of the detector an enhanced pre- and finalscan is performed. The procedures have been applied in an anechoic chamber in the frequency range 30 MHz -1 GHz. By this way automated emission measurements for intermitted signals can be performed in very short times. For stationary emission the measurements speed is limited by the motor speed of the turntable.