ATTENUATION IN EXTENDED STRUCTURES COATED WITH THIN MAGNETO-DIELECTRIC ABSORBER LAYER

Abstract

Thin absorbing layers containing magnetic alloy or ferrite inclusions can be efiectively used for attenuating common-mode currents on extended structures, such as power cords, cables, or edge- coupled microstrip lines. An analytical model to evaluate attenuation on the coaxial line with the central conductor coated with a magneto- dielectric layer is proposed and validated by the experiments and numerical modeling. The analytical model is validated using available magneto-dielectric samples of difierent thicknesses. This model can serve for comparing and predicting the absorptive properties of difierent samples of magneto-dielectric materials, whose compositions may be unknown, but dielectric and magnetic properties can be determined by independent measurements over the specifled frequency ranges. From modeling the absorption in a coaxial line with a wrapped central conductor, it could be concluded whether it is reasonable to use this particular material in such applications as a shield on an Ethernet or other cable, for reducing potential common-mode currents and unwanted radiation in the frequency range of interest.