Electromagnetic noise suppression composite sheets made of hexagonal ferrite particles

Ranajit Sai, Mitsuharu Sato, Yasunori Miyazawa, Akihiro Takahashi, Masahiro Yamaguchi

Research output: Contribution to journalArticlepeer-review

5 Citations (Scopus)


Three different compositions of hexagonal ferrites-M-type (SrCo1.4Ti1.4Fe9.2O19), Y-type (Ba2Zn2Fe12O22), and Z-type (Ba3Co1.25Zn0.75Fe24O41)-are studied to explore their suitability as an electromagnetic (EM) noise suppressor for 6 GHz band. The metal substitutions are chosen to achieve the largest possible noise suppression capabilities at the desired frequency. Static magnetic characterization reveals excellent soft magnetic properties of Z-type powder with MS of 51 eμg and HC of just 8 Oe. However, the high-frequency properties of the Y-type sample are superior to the rest. It possesses the highest μr ′ of 3.8 and noise suppression figure of merit ω × μr ′ ′ (ω) of 23.8 GHz-more than 200% enhancement on the data previously reported by us at 6 GHz. Consequently, the ferrite-epoxy-based composite sheets comprised of 50 vol% of Y-type hexaferrite as magnetic inclusion exhibits the loss ratio, PLoss/PIn, of 0.21, while the loss ratio of just 0.12 corresponds to more than 10 dB of EM noise suppression. An analytical model based on high frequency structure simulator is created to validate the measured loss ratio and to predict noise suppression capability of any given magnetic sheet.

Original languageEnglish
Article number8418837
JournalIEEE Transactions on Magnetics
Issue number11
Publication statusPublished - 2018 Nov


  • Ferromagnetic resonance (FMR)
  • Hexaferrite
  • Noise suppression sheet
  • Permeability


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