• 한국자기학회지
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• 제22권6호
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• pp.210-215
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• 2012

단층형 전자파 흡수체의 흡수 성능은 입사파의 반사 손실(return loss)이 최대가 되는 두께 정합 조건 및 주파수 정합 조건에서 최적화 된다. 본 연구에서는 재료의 복소 투자율과 복소 유전율에 의존하는 전송선 이론을 적용하여 광대역 흡수체의 정합 조건을 계산하였다. 그 결과 주파수에 따른 복소 투자율 감소 특성이 두께 정합 조건을 광대역으로 확대하는 효과를 지니기 때문에 광대역 전자파 흡수체에 자성 재료가 이용될 수 있다는 것을 알 수 있었다. 따라서 향후 확대될 EMC(Electromagnetic compatibility) 규격을 대비한 차세대 광대역 전자파 흡수체를 만들기 위하여 현재 사용되고 있는 NiZn 페라이트 소결체 보다 포화 자화량이 크고 유전율 값이 작은 자성 재료들을 사용하여야 한다는 것을 보였다.

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 1994년도 추계학술발표회
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• pp.59-68
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• 1994

A wide band design method of an double layerred electromagnetic wave absorber sintered ferrite which has a flat and an anti-grid shape layers is proposed and discussed. The wide band electomagnetic wave absorber can be designed by the equivalent material constants method for the each layer, As a result the wide band ferrite electonmagnetic wave absorber with the band width of 30MHz to 3670, 3680 or 3690MHz were designed under the tolerance limits of -20dB reflectivity.

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 1998년도 추계종합학술대회
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• pp.408-413
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• 1998

Electromagnetic wave absorbers for anechoic chamber are needed to broaden the useful frequency bandwidth, reduce the thickness, and decrease the weight. There are various absorbers proposed for the above conditions, but they could not decisively solve it the alone requirements. The Electromagnetic wave absorber made by a conventional ferrite tile has, for example, broadened the useful frequency bandwidth by the way of forming air layer(practically use urethane foam, etc.) on the ferrite tile. Therefore, an air layer is formed between a reflection plate and a sintered Ni-Zn ferrite tile of 7 mm in thickness, which has reflectivity less than -20 dB from 30 MHz to 600 MHz in bandwidth. Accordingly, in this paper, a broadened electromagnetic wave absorber will be designed, which has the reflection characteristics less than -20 dB from 30 MHz to 6000 MHz in the bandwidth. Then we will design a super broadband electromagnetic wave absorber by inserting square Ferrite Cylinders Type with the thickness less than 11 m and with the frequency band from 30 MHz to 6000 MHz under the above tolerance limits. The purpose of this research is on the development of a universal anechoic chamber for measuring radiated electromagnetic wave or immunity of electronic equipments, GTEM-cell, wall material for prevention TV ghost, etc.

• 한국항해학회지
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• 제19권4호
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• pp.93-102
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• 1995

A design method of an electromagnetic wave absorber with ferrite fins in the second layer, which has very wide band frequency characteristics, is proposed and discussed. A theoretical model using the equivalent material constants method is adopted, assessed for its accuracy by comparision with the Hashin-Shtrikman formulas and compared with the conventional absorbers. Based on the model, a wide band electromagnetic wave absorber with excellent reflectivity frequency characteristics in frequency range of 30MHZ to 3530MHZ has been designed.

• Journal of electromagnetic engineering and science
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• 제4권2호
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• pp.51-55
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• 2004

With the progress of the electronics industry and radio communication technology, certain problems, such as electromagnetic interference(EMI), have arisen due to the increased use of electromagnetic(EM) waves. International organizations such as CISPR, FCC, and ANSI have provided the standards for the EM wave environment and for the countermeasure of the electromagnetic compatibility(EMC). EM wave absorbers are used for constructing an anechoic chamber to test and measure EMI and electromagnetic susceptibility(EMS). In this paper, we have designed an one-body EM(electromagnetic) wave ferrite absorber, based on the equivalent material constants method for both normally and obliquely incident waves, whose absorption abilities are superior to that of the conventional ones. The fabricated absorber has a thickness of 27.68 mm and shows an absorption ability over 20 ㏈ in the frequency from 30 MHz to 6 ㎓.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2002년도 춘계합동학술대회 논문집
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• pp.45-49
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• 2002

In this paper, we have studied about electromagnetic wave absorbing properties of ferrite-rubber composite with a variation of ferrite. Amounts of ferrite in a composite absorber were changed from 52 wt.% to 62 wt.%. As a result, it has been shown that the electromagnetic wave absorbing properties of ferrite-rubber composite are related to the amount of ferrite in composite absorber. As a summary, it could be controled the electromagnetic wave absorbing property of ferrite-rubber composite by changing some kinds of annex A and amount of ferrite.

• 한국전자파학회논문지
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• 제14권3호
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• pp.290-295
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• 2003

Sheet형 전파흡수체를 제작하여 Mn-Zn페라이트의 입자크기에 따른 전파흡수능의 관계를 조사하였다. 입자 크기가 증가함에 따라 정합주파수는 낮은 쪽으로 이동하였으며, 정합주파수에서 전파흡수능은 감소하였다. 하지만 휴대폰의 사용주파수인 0.8 ㎓와 1.8 ㎓에서는 입자의 크기가 큰 것으로 구성되어 있는 전파흡수체자 작은 입자로 구성되어 있는 전파흡수체보다 우수한 전파흡수능을 나타내었다. 따라서 휴대폰용 전파흡수체를 Mn-Zn 페라이트 파우더로 제작할 경우에는 입자의 크기가 큰 것이 바람직하다고 생각된다.

• Journal of electromagnetic engineering and science
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• 제12권1호
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• pp.20-25
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• 2012

In this paper, the EM wave absorber for ETC system was designed and fabricated. We fabricated several samples in different composition ratios of flaked sendust and CPE(Chlorinated Polyethylene). Absorption abilities were simulated in accordance with different thicknesses of the prepared absorbers and changed complex relative permittivity and permeability according to composition ratio. The optimized mixing ratio of flaked sendust and CPE was found as 60 : 40 wt.% by experiments and simulation. Then the EM wave absorber was fabricated and tested using the simulated data. As a result, the developed EM wave absorber has the thickness of 2.75 mm and absorption ability was 22.5 dB in the case of normal incidence at 5.8 GHz. Therefore, it was confirmed that the newly developed absorber can be used for ETC system.

• 한국항해항만학회지
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• 제27권1호
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• pp.75-80
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• 2003

천연세라믹, 옻칠, 그리고 고무의 전파흡수능을 조사하였다. 천연세라믹은 2.5GHz~4.5GHz의 주파수 범위에서 2.5dB이상의 전파흡수능을 나타내었으며 옻칠의 전파흡수능이 기존에 전파흡수체의 지지재로 이용되는 고무에 비해 우수한 전파흡수능을 갖고 있음을 확인하였다. 페라이트에 옻칠을 지지재로 이용한 전파흡수체에 대하여 시뮬레이션 한 결과 0.5GHz~10GHz의 주파수 범위에서 16dB 이상의 우수한 전파흡수능을 나타내었다. 따라서 기종에 지지재로 이용하던 고무대신 본 연구에서 새롭게 제안하는 옻칠을 전파흡수체의 지지재로 이용하는 것이 광대역에서 우수한 전파흡수체를 얻을 수 있을 것으로 예상된다.

• International Journal of Internet, Broadcasting and Communication
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• 제10권4호
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• pp.1-5
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• 2018

The property of magnetic field and properties of EMW(Electro Magnetic Wave) absorption with multi-shaped EMW absorber was simulated. As a magnetic field having high density was showed at bottom of EMW absorber, simulation showed that overall EMW was absorbed at the bottom of multi-shaped absorber. The absorption properties of EMW according to thickness of absorber showed that it enhanced about 50-60 percent. Also, EMW absorption properties was checked with surface area of EMW absorber. A cylinder-shaped EMW absorber exhibited good property among multi-shaped EMW absorber based on these result.