Detailed study of different cable ferrite characterization methods using simulation and measurement

Cable ferrites are noise suppression components acting as a common-mode filter. In former work a new characterization method for cable ferrites, using a TEM waveguide, was described. It provides a new set of more representative ferrite parameters. From these parameters, the impedance of the currently widely used wire-loop setup measurement can be derived as well as for other terminations of the wire. In this paper, the drawbacks of the wire-loop setup are investigated in greater detail. As found by an emission measurement, the attenuation of any type of cable ferrites extends above 1 GHz. That fact could be validated by looking at a combination of the new primary ferrite parameters, namely the propagation coefficient. In this paper, we take a closer look at the ferrite parameters above 300 MHz and we show an improved characterization fixture with higher precision for repeated measurements, which gives the possibility to compare different cable ferrite geometries.