Effect of shape of Sendust particles on their electromagnetic properties within 0.1–18 GHz range

The microwave permeability dispersion behaviors and microwave-absorbing properties for different shapes of Sendust particles prepared by vibrating ball milling at 35 vol% in paraffin wax matrix have been investigated. The dispersion spectrum of permeability was calculated by the Landau–Lifshitz–Gilbert equation and Bruggeman’s effective medium theory. The calculated results are in agreement with the experiment data. According to the calculation results, the value of (μ0−1)fr (μ0 is static permeability, and fr is resonance frequency) for flake particle with larger aspect ratio reached 59.1 GHz and exceeded the Snoek’s limit. Considering the quarter-wavelength model and transmission line theory, the microwave absorption peak was discussed. At the frequency range, the flake particle with larger aspect ratio can make a thinner absorber. It provides a way to decrease layer thickness of magnetic absorber.