• Title/Summary/Keyword: Microwave Absorber

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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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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.

Permittivity Adjustment and Impedance Matching of Ferrite Composite Microwave Absorber (복합 Ferrite 전파흡수체의 유전율 제어 및 임피던스 정합)

  • 최경구;조성백;권경일;김성수;김재묵
    • Journal of the Korean Ceramic Society
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    • v.29 no.4
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    • pp.293-297
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    • 1992
  • A proper combination of complex permeability and permittivity is necessary to produce the zero-reflection microwave absorber with an impedance matching. Increasing of dielectric permittivity and development of an impedance matching was investigated in ferrite-rubber composite specimens by addition of conducting materials. Graphite powder of high dielectric constant was added to the composite specimens to increase the permittivity. The precise estimation of graphite content to produce the matched-wave-impedance absorber at a given frequency can be made by using the numerically derived solution map of impedance matching. It was suggested that permittivity adjustment is an effective technique to obtained the microwave absorber with both good absorbing properties and small thickness as well.

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A Study on Measuring Technique of Electromagnetic Wave Absorbing Characteristics of Microwave Absorbers (전파흡수체의 전파흡수특성측정기법에 관한 연구)

  • 김동일;안영섭;정세모
    • Proceedings of the Korean Institute of Navigation and Port Research Conference
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    • 1992.10a
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    • pp.2-29
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    • 1992
  • According to the increase of occupation density of microwave frequency band on use microwave environments have been congested extensively. For shielding unnecessary electromagnetic wave of preventing the electromagnetic wave reflection a good conductor a low resistive material or a lossy material is mainly used. As a method to measure the absorbing characteristics of microwave absorber the fundamental microwave measuring method can be used. There is however a big problem in measuring errors since the wavelength of microwave is very short especially as in the case as microwave absorber for RADAR. Therefore this research aimed to a converting adaptor of 20mm${\Phi}$ coaxial tube from a Type-N connector to 20mm${\Phi}$ coaxial tube and to use it for designing microwave absorber and evaluating absorbing characteristics. Furthermore the measurements of absorbing characteristics and material constants have performed and reviewed which were carried out by using the coaxial tube in the short type and by using rectangular waveguide respectively As a result the validity of the measured values have been confirmed.

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A Study on Development of High Performance Microwave Absorbers in Wide-Band Type for RADAR (레이다용 광대력형 고성능 전파흡수체의 개발에 관한 연구)

  • 김동일;안영섭;정세모
    • Journal of the Korean Institute of Navigation
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    • v.15 no.1
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    • pp.1-9
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    • 1991
  • The coaxial sample holder with 20mm in diameter and the adaptor from type N connector-to-20mm${\phi}$ coaxial tube are designed and manufactured which have been used for designing and measuring the fabricated microwave absorber. In addition, the measure in method of material constants of the microwave absorbers is described, which is focused on minimizing the error due to the sample's shapes, the fitting conditions, etc. After describing the design method of a single-layed microwave absorber, the microwave absorbers for X-band, C-band and S-band RADARs are designed and fabricated, respectively, which are composed of ferrite, carborn, and binder and have good performance. Futhermore, we develop the high performance microwave absorber in extremely wide-band type for RADAR, which is composed of different material and its mixing ratio and which could cover nearly from 4 to 10 GHz.

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The Material Constants and Microwave Absorbing Characteristics of ferroxplana Composite Microwave Absorber (복합 ferroxplana 전파흡수체의 재료정수와 전파흡수 특성)

  • 신재영;오재희
    • Journal of the Korean Magnetics Society
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    • v.1 no.2
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    • pp.49-54
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    • 1991
  • In this study the correlation between material constants and microwave absorbing characteristics of ferroxplana composite microwave absorber used in X-band was investigated. The real part of permeability(${\mu}_{r}'$) was decreased and the imaginary part of permeability(${\mu}_{r}"$) of ferroxplana composite was increased with increaing ferroxplana loading ratio(F/R). The frequency showing maximum attenuation was shifted to lower frequency with increasing absorber thickness. The absorber 2.6 mm thick showed good band width property and 3.2 mm thick showed good attenuation property. From the apphcation of ferroxplana composite's material constants to the region of material constants which satisfy broad band width, it is found that the absorbing characteristics were estimated quantitatively. Estabhshment of material constants' region which satisfies broad band width can make practical application to design of high performance ferrite microwave absorber.

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