The effects of size and shape of iron particles on the microwave absorbing properties of composite absorbers

Ruey Bin Yang, Wen Fan Liang, Siu Tong Choi, Chung Kwei Lin

Research output: Contribution to journalArticlepeer-review

22 Citations (Scopus)


High values of magnetic permeability and dielectric permittivity of polymer composite containing flake-shaped iron particles were prepared by the mechanical milling of two batches of iron powders [Fe(A) and Fe(B)] under controlled conditions. The frequency-dependent complex permittivity (ε′-jε″) and permeability (μ′-jμ″) of resin composites with 40 wt.% of flake-shaped iron particles are investigated in 2-18 GHz. The results show that all ε′, ε″, μ′, μ″ substantially increase due to the increase of milling time and the size of the flake-shaped particles. The enhancement of space-charge polarization increases the permittivity of the composite absorbers. The frequency dispersion of μ″ of flake-shaped Fe/epoxy composites show a higher resonance frequency (around 3 GHz) which exceeds the Snoek's limit in the gigahertz range due to their low eddy current loss coming from the particle shape effects. For 40 wt.% composite with 2 mm thickness, the predicted reflection loss reaches - 19.4 dB at 14.9 GHz for Fe(A)/2 hr, -28.0 dB at 8.96 GHz for Fe(A)/4 hr, -31.6 dB at 11.6 GHz and -42.9 dB for Fe(B)/2 hr at 7.84 GHz for Fe(B)/4 hr as magnetic fillers.

Original languageEnglish
Article number6558948
Pages (from-to)4180-4183
Number of pages4
JournalIEEE Transactions on Magnetics
Issue number7
Publication statusPublished - 2013


  • Complex permeability
  • complex permittivity
  • flake-shaped iron powder
  • reflection loss

ASJC Scopus subject areas

  • Electrical and Electronic Engineering
  • Electronic, Optical and Magnetic Materials


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