A novel characterization method for cable ferrites using a TEM-waveguide test setup

Cable ferrites are widely used on wires attached to electronic devices and components to fulfill the requirements of the EMC regulations. Until today many manufacturers of those passive components refer to a simple measurement procedure in order to obtain a ferrite-impedance-versus-frequency-chart for their datasheets. This setup renders only a special case for the cable termination which is far away from a realistic application. From the datasheet graph one could conclude that a particular ferrite is less useful above its peak impedance. We want to correct this misinterpretation, as our investigation clearly shows that the attenuation can reach up to several gigahertz. In the following paper we describe a new approach for the characterization of cable ferrites, using a TEM-waveguide. This leads to an equivalent circuit with a new set of more representative ferrite parameters.