• 전자공학회논문지A
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• 제32A권1호
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• pp.70-78
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• 1995

In order to implement broadband RAM's(Radar Absorbing Materials) made up of multiple dielectricl layers, the design variables such as the dielectrci constaints, the depths and the loss tangents of dielectric are optimized. The wave impedances regarding the reflective wave are found in dielectrics, input impedances and reflection coefficients with multiple dielectric layers are derived from the transmission line circuit theory. Finally, minimum average reflective power and optimum design variables are obtained by applying the numerical technique, called modified Powell method. In case of four dielectric layers with inequality constraints in design variables, a quite favourable and feasible result with the total depth of 1.1 cm, the average reflective power of 0.85% over the bradband frequency range is obtained for a specific example.

• 한국전자파학회지:전자파기술
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• 제4권3호
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• pp.3-10
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• 1993

전파흡수체의 전파흡수능 측정방법은 기본적으로 다양한 마이크로파 측정법이 이용될 수 있지만, 레이다용 전파흡수체의 경우, 전파의 주파수가 높기 때문에 파장이 짧아서 측정오차가 큰 문제점이 있다. 따라서, 지금까지는 $20mm\Phi$동축관 및 구형도파관을 이용한 재료정수측정법과 전파흡수능측정기법에 관하여 검토하여 왔다. 본 논문에서는 그동안 실험실적으로 설계하여 온 X-Barn Radar용 전파홉수체를 실용의 상태에 가까운 반사 전력법에 의하여 그 성능을 예비평가하고, 실제의 target를 제작하여 X-Band Radar로 실장실험한 결과에 관하여 보고한다.

• 한국전자파학회논문지
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• 제20권7호
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• pp.625-630
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• 2009

본 논문에서는 함정에 탑재된 탐색 레이다의 선호 왜곡 현상에 대한 분석 및 대책에 대해 소개한다. ShipEDF 프로그램을 이용하여 탐색 레이다의 주 안테나와 함정 구조물을 전자기학적으로 모델링하고, 광선 추적 기법을 이용하여 탐색 레이다의 자유공간 및 함정 탑재 상태에서의 복사 패턴을 분석한다. 분석된 복사 패턴을 통해 탐색 레이다의 선호 왜곡 현상이 마스트의 전자파 반사로 인한 복사 패턴 왜곡에 의한 것임을 알 수 있었고, 이에 대한 대책 수립을 위해 탐색 레이다에 의한 마스트 표면 전류 분포를 분석한다.

• 한국전산유체공학회지
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• 제17권4호
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• pp.56-68
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• 2012

Nowadays, Unmanned Combat Air Vehicle(UCAV) has become an important aircraft system for the national defense. For its efficiency and survivability, shape optimization of UCAV is an essential part of its design process. In this paper, shape optimization of UCAV was processed for aerodynamic performance improvement and Radar Cross Section(RCS) reduction using Multi Objective Genetic Algorithm(MOGA). Lift and induced drag, friction drag, RCS were calculated using panel method, boundary layer theory, Physical Optics(PO) approximation respectively. In particular, calculation applied Radar Absorbing Material(RAM) was performed for the additional RCS reduction. Results are indicated that shape optimization is performed well for improving aerodynamic performance, reducing RCS. Further study will be performed with higher fidelity tools and consider other design segments including structure.

• 한국군사과학기술학회지
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• 제22권1호
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• pp.81-92
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• 2019

Stealth means the reduction of all signature including the reflection/emission of radar, infrared, visible light and audio signals. Stealth aircraft can significantly improve the penetration capability, the combat survivability and the mission effectiveness. This paper presents the basic concept, the key elements and the application examples of stealth aircraft technology. Also it briefly describes the effect of the modern stealth aircraft on the future air warfare.

• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2005년도 춘계학술발표대회 논문집
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• pp.141-145
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• 2005

Since the electromagnetic properties of fiber reinforced polymeric laminate composite can be tailored effectively by adjusting its composition and regulating the stacking sequence, it is plausible material for fabricating the radar absorbing structures (RAS) of desired performance. In order to design the effective electromagnetic wave (EM) absorber with the fiber reinforced polymeric laminate composite, its electromagnetic characteristics should be available and could be regulated easily in the target frequency bands. In this study, dielectric characteristics of the E-glass/epoxy laminate composites were measured by the free space method in the X-band frequency range ($8.2\;{\sim}\;12.4\;GHz$). In order to describe the dielectric behavior of laminate composites of arbitrary stacking sequences, the equivalent circuit model and the laminating equations for estimating dielectric properties were proposed, and experimentally verified. From the comparison of the predicted and measured data, the proposed method predicted well the experimentally measured data.

• 한국항해학회지
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• 제16권4호
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• pp.25-34
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• 1992

As a method of measure the absorbing characteristics of microwave absorber, the various microwave measuring method can be used fundamentally. There is, however, a big problem in measuring errors, since the wavelength of microwave such as used for radar is very short. Therefore, this research aimed to design and fabricate a converting adaptor of $20mm^{\phi}$ coaxial tube from a Type-N connector to $20mm^{\phi}$ coaxial tube and to use it for evaluating absorption characteristics of microwave absorber. Furthermore, the measurements of absorbing characteristics and material constants have been performed and review, which were carried out by using the coaxial tube and by using rectangular waveguide, respective. As a result, the validity of the proposed measuring method has been confirmed.

• 한국전자파학회지:전자파기술
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• 제4권1호
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• pp.10-19
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• 1993

전파홉수체의 전파홉수능 측정방법은 기본적으로 다양한 마이크로파 측정법이 이용될 수 있지만, 레이다용전파홉수체의 경우, 전파의 주파수가높기 때문에 파장이 짧아서 측정오차가큰문제점이 있다. 따라서 본 연구에서는 전파홉수체의 전파홉수능을 실험적으로 간단히 측정할 수 있게 하기 위한 2 20rnrn¢동축관 생플흘더 및 Type-N connector로 부터 $20mm\phi$동축관으로의 변환Adaptor를 제작하여 전파홉수체의 설계 및 특성(전파홉수능) 평가에 사용할 수 있게 하였다. 또 구형도파관을 이용한 재료정수 측정법을 채용하여 시료의 형상동의 영향을 적게 받는 실측 방법에 관하여 검토하였다. 나아가서, 구형도파관을 이용한 재료정수 측정치를 반사감쇠량으로 환산한 전파홉수능파 동축관으로 측정한 전파흡수능의 주파수 특성을 구하여 거의 일치함을 밝히고 있다.

• 한국군사과학기술학회지
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• 제1권1호
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• pp.114-127
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• 1998

A user friendly computer code(EMCOMST; Electro-Magnetic response for COMposite STructures) was developed which provides with computations of the response characteristics such as reflectance and transmittance to the incident wave angles, frequencies, composite thicknesses, ply orientations, and types of backplate as the linearly polarized transverse electro-magnetic wave is emitted to the advanced composite structures. In this investigation were reviewed the electromagnetic characteristics of the continuous orthotropic fiber-reinforced organic matrix composites with or without ferrite fillers, which are actively applied to low-weight and high-strength aircraft structures. Also were calculated the response of the three layered compound structures which have appropriately stacked above-mentioned materials as transmitting layer, absorbing layer, reflection layer, respectively under the specific thickness constraints for mechanical strength design requirements. For the composite structures presented in this study, minimum reflectance value less than -5㏈ can be obtained in the frequency range of 4 to 12 ㎓. In addition, analysis of structures attached isotropic radar absorbing materials(RAM) is facilitated by putting the material properties in the material input card entries adequately.

• Composites Research
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• 제17권5호
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• pp.68-77
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• 2004

레이더 혹은 전자-통신장비에서 방출되는 전자파의 흡수/차폐는 군사적인 목적뿐만 아니라 상업적 목적으로도 매우 중요하다. 효과적인 전자기파 흡수체를 설계하기 위해서는 흡수체에 사용되는 재료의 대상 주파수 대역에서의 전자기적 성질을 정확히 알아야 하며, 손실재의 함량에 따른 정확한 전자기물성 예측이 가능해야 한다 본 연구에서는 전도성 카본 블랙 나노 입자를 함유하는 폴리에스터 복합재료의 유전성질을 자유공간 기법을 이용하여 X-Band 주파수 대역에 걸쳐 측정하고 카본 블랙의 함량에 따라 정량적으로 분석하였으며, 임의의 카본 블랙 함량을 갖는 고분자 수지의 유전 물성을 주파수에 따라 예측할 수 있는 방법을 제시하고 검증하였다.