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

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 the measurement procedure prescribed from the (CISPR 16) Standard Rules. The technique takes reference to the common mode and differential mode components of voltage and current measured in 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