Ultrabroad bandwidth and matching characteristics for spinel ferrite composites with flaky fillers

Spinel ferrite flakes $Ni0.97−xZnxCo0.03Fe2O4$ with $x=0.5$ and 0.65 are prepared for use as fillers in electromagnetic composites. The composites with the flaky fillers exhibit greatly enhanced high-frequency and attenuation properties. The complex permeability, $μ0′$ and $μmax″$⁠, is enhanced by about 500%–700%, and the relative attenuation bandwidth $WR$ is increased by 300%–440%, as compared to those for composites with conventional spherical fillers. $WR$ achieves 90% of the theoretically maximum relative bandwidth. The composites with the spinel ferrite flaky fillers are powerful and potential candidates as electromagnetic attenuation materials with ultrabroad bandwidth at microwave L, S, and C bands.