Technical background

Ferrite technology

The basis of this technology is a high quality ferrite powder. KABELWERK EUPEN developed a special compound; a polymer material mixed with a considerable quantity of homogeneously fine ferrite powder. This compound is called EMC/COM and it can be extruded around copper conductors. The ferrite itself is a non-conducting material, but it has a very interesting magnetic behaviour. As a ferromagnetic material, it will go through hysteresis loops whenever it is under influence of an alternating magnetic field. Consecutively magnetising and demagnetising the material will cause considerable losses of high frequency energy. This energy is absorbed in the ferrite grains and converted into heat. This effect is more or less proportional to the field frequency. By coating conductors with a thin layer of ferrite compound, high frequencies will be strongly attenuated, because their energy will be absorbed by the ferrite powder. This applies to high frequency disturbances that are propagating on the conductor and which we don't want to disturb the environment, as well as to surrounding interferences, which we want to prevent from disturbing the signals on our cable. The obtained attenuation is proportional to the cable length. Moreover, the ferrite layer's continuous spreading over the whole cable length makes sure that there will be no sudden changes in characteristic impedance along the cable. Otherwise, such discontinuities might cause high frequency signals to be reflected at those spots and to be sent back to the source or to other devices. At least, it is important to emphasise that a ferrite coated conductor will divert much less disturbances to the earth. This is an interesting feature because disturbances that "disappear" to earth are not really gone: they will re-emerge elsewhere and cause problems. Over the last 20 years, KABELWERK EUPEN's ferrite technology has been used in a large number of applications. We distinguish between applications where each individual conductor is ferrite coated ("LP - Low Pass cable") and those  where the complete, overall assembly of conductors is coated with ferrite compound ("CMS - Common Mode Suppression cable")