• 전자공학회논문지D
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• 제36D권4호
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• pp.18-24
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• 1999

본 논문에서는 완전도체구의 전파흡수제를 설계하는 방법을 제시하였다. 코팅된 구의 역산란파는 반사파와 creeping wave의 합으로 표현된다. 현재는 곡률을 가진 산란체의 경우일지라도 단순히 반사파의 반사계수를 0이 되게 하는 저파흡수제를 설계하였다. 크기가 작은 완전도체구의 전파흡수체를 설계하기 위해서는 반사파 뿐만 아니라 회절파인 creeping wave에 의한 영향도 함께 고려해 주어야 한다. 이를 위해 코팅된 구의 고유함수해의 역산란파가 0이 되는 조건을 Newton-Raphson 수치 해석 방법을 이용하여 전파흡수체를 설계하였다. 본 연구에서 제안한 방법으로 전파흡수체를 설계하여 크기가 작은 완전도체구에 코팅하였을 경우 기존의 무한 평면으로 가정하여 구한 전파흡수체 보다 우수한 흡수 성능을 보였다.

• 한국항해항만학회지
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• 제34권7호
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• pp.539-542
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• 2010

In this paper, we designed and fabricated the Electro-Magnetic (EM) wave absorber for wireless LAN by using Amorphous and CPE. The material constants and the absorption properties were measured for the samples containing 50 %, 60 %, and 70 % weight fraction of Amorphous. Moreover, the EM wave absorption abilities were simulated for the EM absorbers in different thicknesses by adopting the measured permittivity and permeability, and then the EM wave absorber was fabricated based on the simulated design values. As a result, the EM wave absorber with the composition ratio in Amorphous : CPE = 60 : 40 wt.% with the thickness of 4 mm has the absorption ability more than 35 dB at 2.4 GHz. Thus, it is expected the wireless LAN environment can be improved by using the developed absorber.

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2005년도 춘계종합학술대회
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• pp.551-554
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• 2005

국제 규격을 충족하는 전파무향실을 구축하기 위하여 광대역성을 가지는 페라이트 전파흡수체에 피라미드형 카본 혼입 발포 유전체 전파흡수체를 부착시킨 초광대역성 전파흡수체의 설계 방법을 제안하였다. 기존의 페라이트 전파흡수체는 흡수능 20 dB이상을 만족하는 주파수 대역이 30 MHz에서 6 GHz 였으나 본 논문에서 제안하는 페라이트 전파흡수체 위에 피라미드형 유전체 전파흡수체를 적층시킨 전파흡수체는 흡수능 20 dB이상을 만족하는 주파수 대역이 30 MHz에서 18 GHz까지 확장되었고 그 전체 두께는 14.26 cm이다.

• 한국항해학회지
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• 제15권4호
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• pp.13-25
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• 1991

Recently, according to the development of electromagnetic wave technique, more frequent and powerfull wave radiation becomes inevitable and so electromagnetic environments has become worse accordingly. Electromagnetic wave absorber is known the most effective preventive remedy to cope with the EMI/EMC problem. To realize broad-band electromagnetic wave absorber, triple layered structure where an air layer is interposed between a sintered ferrite layer and a ruber ferrite layer was adopted. Computer simulation for optimum design and evaluation of absorption characteristics has been made. The results shows that designed broad-band electromagnetic wave absorber can be useful for EMI/EMC problem, especially reducing TV ghosts in both VHF and UHF bands by additionally an air layer and a thin rubber ferrite layer on the surface of conventional ferrite, without replacing it.

• 한국해양공학회지
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• 제16권3호
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• pp.1-7
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• 2002

In this paper, a numerical model to analyze the performance of a vertical slit-type wave absorber is developed under the assumption of inviscid water waves. The formulation combines the linear potential theory with a semi-empirical description of the eddy-shedding at a slit-type wave absorber. We investigated the reflection coefficients over a wide frequency range for a vertical slit-type wave absorber both with and without a solid rear wall. Model test was conducted at KRISO' s two dimensional wave tank to validate the theoretical results. It is found that the agreement between theoretical results and experimental data is surprisingly good. We found that the wave absorbing system using a vertical slit plate has sufficient potentials for breakwaters for ocean development.

• 한국전자파학회논문지
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• 제20권6호
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• pp.562-569
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• 2009

최근 DSRC, 협대역 통신 방식을 이용하여 고속도로 톨게이트에 Hi-pass(차량의 무정차 자동 요금 징수)를 운용하고 있지만, 전파의 다중 반사로 인한 전파 간섭이 발생하여 시스템의 오류 및 사고가 발생하고 있다. 이러한 문제들은 전파 흡수체를 사용하여 해결할 수 있다. 본 논문은 전파 흡수 재료인 비정질 재료와 지지재인 CPE를 배합하여 최적의 조성비를 찾고 DSRC용 전파 흡수체를 개발하는 연구를 하였다. 그 결과, 조성비 비정질 재료 :CPE=45:55 wt.%, 두께 2.65 mm인 전파 흡수체가 5.8 GHz에서 40 dB 이상의 흡수능이 얻어지도록 개발하였다.

• 한국전자파학회:학술대회논문집
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• 한국전자파학회 2005년도 종합학술발표회 논문집 Vol.15 No.1
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• pp.415-420
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• 2005

To construct an anechoic chamber for EMI test satisfying some international standards, it has been recognized that the absorption characteristics of the EM wave absorber must have more than 20 dB over the frequency band from 30 MHz to 18 GHz. In this paper, an EM wave absorber with super wide-band frequency characteristics was proposed and designed in order to satisfy the above requirements by using the EMCM[1]. As a result, the proposed absorber has absorption characteristics more than 20 dB over the frequency band from 30 MHz to more than 20 GHz.

• Journal of electromagnetic engineering and science
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• 제8권2호
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• pp.70-75
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• 2008

In this paper, the EM wave absorber was designed and fabricated for countermeasure against EMI from a ceiling of a tollgate in ETC system. We fabricated several samples in different composition ratios of MnZn-ferrite, Carbon, 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 MnZn-ferrite, Carbon, and CPE was found as 40:15:45 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 3.3 mm and absorption ability was more than 20 dB in the case of normal incidence and more than 11 dB for the incident angle from 15 to 45 degrees at 5.8 GHz. Therefore, it was confirmed that the newly developed absorber can be used for ETC system.

• Journal of Magnetics
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• 제21권1호
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• pp.61-64
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• 2016

In this study, we report the as-prepared MgO-doped $BaFe_{12}O_{19}$, which was prepared by calcination technique and high-energy ball milling process, as an electromagnetic wave absorber. The phase analysis of $BaFe_{12}O_{19}$ and the as-prepared MgO-doped $BaFe_{12}O_{19}$ was detected utilizing X-ray Diffractometer (XRD). The microstructure was characterized using Scanning Electron Microscope (SEM). By means of the transmission/reflection coaxial line method, the electromagnetic properties and microwave absorbing properties of the as-prepared electromagnetic wave absorber were studied. It is found that the electromagnetic wave absorber has a minimum reflection loss value of -41 dB at 4.27 GHz with a matching thickness of 2.6 mm. The experiment results revealed that the as-prepared electromagnetic wave absorber could find potential applications in many military as well as commercial industries.

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 1994년도 춘계학술발표회
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• pp.43-48
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• 1994

A wide band design method of an electromagnetic wave absorber using exponentially tapered ferrite which has very wide band frequency characteristics is proposed and discussed. The wide band electromagnetic wave absorber can be designed by the proposed equivalent material constants method for the regions varying spatially in the shape of ferrite. Furthemore the wide band ferrite electromagnetic wave absorbers with taper which have not only excellent reflectivity frequency characteristics but also the band width of 30MHz to 2150 or 2450MHz under the tolerance limits of -20dB reflectivity were designed.