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 (mu(0) - 1)f(r) (mu(0) is static permeability, and f(r) 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 away to decrease layer thickness of magnetic absorber. (C) 2011 Elsevier B.V. All rights reserved.