• Title, Summary, Keyword: Microwave ferrite

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Control of Matching Frequency of Ferrite Composite Microwave Absorber Consisted of Two Kinds of Ferrites (2종의 Ferrite가 혼합된 복합 Ferrite 전파흡수체의 정합주파수 제어)

  • 권형주;신재영;오재희
    • Journal of the Korean Ceramic Society
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    • v.30 no.10
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    • pp.823-828
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    • 1993
  • The performance of ferrite composite microwave absorber has been evaluated as the matching frequency, the matching thickness and the band width. Especially, matching frequency is very important in application of microwave absorber because it determines operating frequency range. In this study, the ferrite composite microwave absorbers consisted Ni-Zn ferrite and Zn2Y ferroxplana were prepared in order to control matching frequency. Then, the variation of the material constants and microwave absorbing characteristics were investigated with various ferrite mixing ratio. The material constants of ferrite composite microwave absorber could be controlled by variation ferrite mixing ratio. Therefore, it was confirm that matching frequency of microwave absorber could be shifted by control of material constants.

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Microwave Absorbing Characteristic Improvement by Permittivity Control of Ferrite Composite Microwave Absorber (유전율제어에 의한 복합 Ferrite 전파흡수체의 성능향상)

  • 신재영;권형주;오재희
    • Journal of the Korean Ceramic Society
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    • v.31 no.4
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    • pp.415-419
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    • 1994
  • The material constants(the complex permeability and permittivity) of ferrite composite determine its microwave absorbing characteristics. Therefore, in order to improve the microwave absorbing characteristics, it is necessary to control the material constants of the ferrite composite. In this study, the method of improving microwave absorbing characteristics by control of permittivity of ferrite composite which has not satisfying matching condition in C-X band (4 GHz~12.4 GHz) was investigated. It was possible to control the permittivity by adjusting graphite loading ratio in the ferrite composite microwave absorber. It was also concluded that the control of permittivity of ferrite composite is effective method to improve the microwave absorbing characteristics.

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Microwave Absorption Properties of Ferrite/Rubber Composite Microwave Absorber mixed Ni-Zn ferrite and $Ni_2Y$ ferrite (Ni-Zn 페라이트와 $Ni_2Y$ 페라이트를 혼합한 페라이트/고무복합형 전파흡수체의 전파흡수특성)

  • Kim, H.G.;Kim, S.R.;Lee, S.H.;Cho, H.C.;SaGong, G.
    • Proceedings of the KIEE Conference
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    • pp.1355-1357
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    • 1997
  • In this study, the ferrite/rubber composite microwave absorbers mixed Ni-Zn ferrite and $Ni_2Y$ ferroxplana were prepared in order to control matching condion. The variation of the material constants($\dot{\varepsilon}$, $\dot{\mu}$) and microwave absorbing characteristics were investigated with various ferrite mixing ratio. The material constants of ferrite/rubber composite microwave absorber could be controlled by variation ferrite mixing radio. The matching frequency and thickness could be controlled with various ferrite mixing ratio.

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Structure and Microwave Absorption Properties of Polyaniline/Zn Ferrite Composites

  • Xing, Honglong;Liu, Ye;Liu, Zhenfeng;Wang, Huan;Jia, Hanxiao
    • Nano
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    • v.13 no.9
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    • pp.1850105.1-1850105.12
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    • 2018
  • Polyaniline (PANI)/Zn ferrite composites were fabricated by simple two-step method. The crystal phase, particle size, morphology, thermal stability and conductivity were characterized. Electromagnetic parameters of PANI/Zn ferrite composites were measured at room temperature in the frequency of 2-18 GHz. The prepared composite had an amorphous fluffy structure, Zn ferrite nanoparticles with diameters ranging from 20 nm to 30 nm are encapsulated in PANI or on PANI surface, and the thermal stability of the composite is poor. But Zn ferrite content plays a key role in influencing this structure and regulating microwave attenuation capability. The PANI/Zn ferrite composites showed an enhanced microwave absorption performance in Ku band at thin coating thickness which corresponds to RL value below -10 dB and the minimum reflection loss (RL) is -54:4 dB at 17.6 GHz with the coating thickness of 1.4 mm.

THE COMPLEX PERMEABILITY AND MATCHING FREQUENCY OF FERRITE MICROWAVE ABSORBER

  • Shin, Jae-Young;Oh, Jae-Hee
    • Journal of the Korean Magnetics Society
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    • v.5 no.5
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    • pp.800-804
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    • 1995
  • The complex permeability dispersions and the microwave absorbing phenomena are investigated in ferrite microwave absorber. The complex permeability of NiZn ferrite, NiZnCo ferrite, and Y-type hexagonal ferrite were measured in 200MHz-14GHz range. Two types of resonances, the domain wall and the spin rotational resonance, were observed. With a ferrite particle with a diameter of about $1\;\mu\textrm{m}$, only spin rotational resonance were observed. The theoretical matching frequency is determined by plotting the measured complex permeability locus on the impedance matching solution map. One or two impedance matching phenomena are observed in the ferrite absorbers according to their complex permeability loci on the impedance matching solution map. The first matching frequency, found in the ferrite-rubber composites, which was higher than that of spin rotational resonance, increased with spin rotational resonance frequency.

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THE MICROWAVE ABSORBING CHARACTERISTICS OF FERRITE GRID ABSORBER

  • Kwon, H.J.;Shon, H.J.;Hur, W.D.;Naito, Yoshiyuki;Takahashi, Michiharu
    • Journal of the Korean Magnetics Society
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    • v.5 no.5
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    • pp.805-809
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    • 1995
  • In order to widen the band-width of ferrite absorber, compositional effect on the complex permeability of Ni-Zn ferrite and the structure of grid absorber were studied. From the experimental results, we could determine the optimum composition composition of Ni-Zn ferrite and the structure of grid absorber. Also, we manufactured grid absorber and investigated its microwave absorbing characteristics. Calculation shows that the ferrite frid absorber suppresses reflection ${\leq}-20dB$ from 30 MHz to 700 MHz and the conventional ferrite tile absorber suppresses reflection ${\leq}20dB$ in the frequency range of 30 MHz-400 MHz. It was found that the microwave absorbing performance of the ferrite grid absorber was superior to the ferrite tile absorber.

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Manufacture of Composite Electromagnetic Absorber using Natural Lacquer Binder (옻을 지지재로 이용한 복합형 전자파 흡수체의 제작)

  • 김동일;최동한;김수정;박우근;송재만;김민정
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.14 no.7
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    • pp.756-761
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    • 2003
  • The microwave absorption properties of silicone, chloride polyethylene(CPE), and natural lacquer which is newly suggested in this study as a binder for composite microwave absorber were investigated to develop a superior microwave absorber. MnZn ferrite composite microwave absorbers mixed with them were prepared and their absorption property was investigated. A MnZn ferrite microwave absorber mixed with natural lacquer showed an excellent microwave absorption property in expanded frequency band.