Microwave attenuation properties of <i>W</i>-type barium ferrite BaZn2−xCoxFe16O27 composites

Abstract

The complex permeability and permittivity, the relationship between dynamic and static properties, and attenuation properties have been studied for BaZn2−xCoxFe16O27 composites with x=0.7–2.0. The results show that the resonance frequency fR is controlled by the out-of-plane anisotropy field Hθ, and the static permeability μ0′ is related to the in-plane anisotropy field Hφ. For appropriate resonance frequency and high complex permeability, the percentage bandwidths of ΔW=Δf/f0&amp;gt;90% for attenuation of 10 dB or more can be achieved by composites with x=0.7 and 1.0. Therefore, W-type barium ferrites with easy c-plane anisotropy are good candidates for electromagnetic materials with low reflectivity over broad frequency range at microwaves.