Automatic test equipment for the measurement of symmetrical and asymmetrical RF interference based on hybrid junctions

The paper describes a measurement technique for conducted EMI measurements. This technique allows a bandwidth improvement in the spectrum analysis of conducted interference produced by a single-phase EUT with respect to the measurement procedure prescribed by the (CISPR 16) Standard Rules. The technique makes reference to the common-mode and differential-mode components of voltage and current measured at a point of the line by sensors with adequate characteristics in absence of dummy loads. The experimental tests performed with the proposed technique have been carried out on a widespread switched-mode power supply. The extension to three-phase systems is also proposed.