• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2002년도 춘계학술대회논문집
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• pp.161-176
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• 2002

Collision avoidance is the most important part of a small vessel. Small and mediurn sized ships are surprisingly poor targets for radar reflection and are frequently in danger of being overrun by large vessels, even under good condition of visibility. One of the best way to prevent collisions at sea is to use as large and well designed a radar reflector. Thus, RCS(Radar Cross Section) increase is key element in the design of radar reflector. Radar Reflectors are normally classified into active-type and passive-type. In this paper, the RCS increase methods for passive-type reflector through shaping are explained, and analyzed with RCS performance test by computer simulation. As results from analysis, It is shown that the effective diameter of radar reflector is over 10 λ to provide a return above the threshold RCS of 25m$^2$, lower limit of detectability using X-band radar in a moderate sea.

• 한국항해항만학회지
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• 제27권3호
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• pp.267-272
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• 2003

This paper describes design method of Passive-type Radar Reflector (PRR) which is to provide the requirement of newly revised 2000 SOLAS regulations on the Radar Reflector. The main target of this work is to find the optimum shape of a radar target having large Radar Cross Section (RCS). Through the RCS analysis based on the theoretical approach, two kinds of PRR models, RRR-F model for use in fisheries and PRR-S model for use in small sized ship, are designed and discussed their RCS performance. RCS measurement tests for the various sized samples are carried out in an anechoic chamber. As evaluation results it was clearly shown that the conventional sphere-type shows optimum shape in case of PRR-S, while the cylinder-type which consists of large sized corner clusters or zig-zag flat plats gives best performance in case of PRR-F.

• Journal of Astronomy and Space Sciences
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• 제26권4호
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• pp.667-676
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• 2009

탑재체 (Payload)는 수동형과 능동형으로 분류되며 , 다양한 형태의 레이더 영상(Radar Image)을 획득하기 위한 위성은 일반적으로 능동형 탑재체인 SAR(Synthetic Aperture Radar)를 이용한다. SAR 위성은 탑재체에서 송신한 전파가 반사되는 것을 획득하여 영상을 형성한다. 때문에 위성이 반사신호를 설계한대로 획득하여 영상을 구성하기 위해서는 궤도에서 실제로 획득한 지상 영상을 기반으로 검보정을 수행하여야 한다. 이에 필요한 것이 지상 목표물인 각면판 반사기(CR; Corner Reflector)이다. 반사기(Reflector)는 다양한 형태가 있으며, SAR를 탑재한 위성의 특성 및 운영목적에 적절하게 설계되어 활용된다. 여기서는 최적의 반사기와 효율적인 반사기들의 특성을 확인하고 그에 대한 고찰을 수행하였다. 또한 그 결과를 바탕으로 삼면판 반사기(Trihedral Corner Reflector)를 설계하고 관련 성능을 확인하였다.

• 한국항해항만학회지
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• 제26권2호
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• pp.199-207
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• 2002

컴퓨터 시뮬레이션을 통해서 레이더 타겟들에 대한 레이더 유효면적(RCS)을 측정하고, 그들의 성능특성을 분석하였다. 또한, 상용레이더 리프렉터의 구조적 특징을 검토하였다. 그리고, 수동형 레이더 리프렉터의 최적 설계조건을 선택했다. 연구결과, X-band($\lambda$=3.2cm에서 10λ 크기의 원형 평판으로 구성된 옥타헤데랄 형태의 레이더 리프렉터가 최적 성능을 나타냈다. 그러나, 새로 적용될 2000 SOLAS 규정을 수용하기 위해서는 X-band 와 S-band 모두에 적용하기 위해서 더 큰 크기의 원형평판이 필요하다.

• 대한원격탐사학회지
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• 제23권6호
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• pp.501-506
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• 2007

본 연구에서는 합성개구레이더(synthetic aperture radar, SAR) 영상의 보정에 사용되고 있는 반사기(corner reflector, CR)를 이용하여 목표물의 식별과 인식을 위한 기초적인 연구를 실시하였다. 사각형 삼면 전파반사기를 기반으로 전방향(omni-directional) 반사기를 제작하였다. 여기서는 한 변의 길이가 15cm인 4-배열 사각형 삼면 전파반사기를 사용하여 C-밴드(주파수: 5.3 GHz) 의 편파별(VV, HH, VH, HV) RCS(radar cross section)특성을 해석하였다. 전파반사기는 대칭형이므로 방위각 180도 범위에 대해서 레이더 산란단면적 패턴을 측정하였다. VV편파의 경우, 방위각에 따른 RCS값의 차이가 8dB정도로 다른 편파보다 전방향 특성이 더 좋은 것으로 확인되었고, 방위각이 $0^{\circ}$ (단면과 동일 방향)와 $45^{\circ}$ (이웃하는 단면들의 중앙) 일 때, 가장 높은 RCS값을 보였다. 또한, 실험에서 얻어진 RCS값을 수치 해석 시뮬레이션과 이론적 계산과 비교를 실시한 결과, 서로 잘 일치하는 것으로 나왔다.

• Journal of Advanced Marine Engineering and Technology
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• 제41권2호
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• pp.171-175
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• 2017

The high-tech large warships are minimal and they are always monitored by opponents, and become primary targets when conflicts occur. The improvement in reducing susceptibility has significant importance because it is difficult for a ship to maintain mission capability and functionality once it is damaged. Ordinary decoys are effective only under the premise that the ship has already been exposed. Traditionally, for naval vessels, techniques related to the radar have been used in military stealth techniques to ensure confidentiality. The corner reflector, on the other hand, can produce rather large radar cross sections. Continued use of deceptive systems such as chaff during operations will help to improve survivability of naval ships. From this viewpoint, corner reflector was considered for making radar countermeasures and deception technology. This paper reviews the current status of corner reflector basis decoys and the technical feasibility of corner reflectors for developing structural decoys.

• 한국항해학회지
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• 제1권1호
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• pp.17-26
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• 1977

A large number of the set-nets are set in Namhaedo coast of Korea. The floats of these set-nets are not only small even in case of large floats but also they scarcely have distinguishable marks such as light buoys or flags, so that they are very hard to be recognized by naked eyes and thus became probable obstacles to navigation for the passing ships and the fishing vessels. In order to research the capability of detecting such nets with Radar, the author investigated a maximum detectable range of the ordinarly large floatsand of a floating corner reflectors of various size and shape by Radar. The results obtained are as follows; 1. A maximum detectable range of large floats at a close range can be calculated by the Radar equation in sufficient accuracy. 2. Large floats of the large set-nets are also detectable by Radar even though it's detectable range boundary was within 0.2-0.65 miles. And the Radar picture of large floats was easier to be found with somewhat higher setting of the gain control on shorter range scale of the 1 mile. 3. Floating corner reflector rather suitable for set-net floats of "S" type reflector proposed in this paper, of which the dimension must be above 17cm in diameter to be detectable by Radar at 2 miles.t 2 miles.

• 해양환경안전학회:학술대회논문집
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• 해양환경안전학회 2003년도 춘계학술발표회
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• pp.125-134
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• 2003

이 논문에서는 새로 개정된 2000 SOLAS 규정에 근거하여 소형선박용 수동식 레이더 리프렉터(PRR-S) 설계에 관해서 기술했다. 이 연구의 설계개념은 PRR-S이 선박요동에 의해서 레이더 반사면적(RCS)이 변동하는 것을 방지하기 위하여 ‘catch rain’ 위치를 유지하도록 한 것이다. PRR-S은 원형판으로 구성한 옥타헤더럴 레이더 리프렉터와 요동방지를 위한 짐발장치로 구성하였다. 설계한 PRR-S는 전파흡수실에서 성능실험을 하였다. 실험결과, 기준으로 정한 Davis Echomaster사의 리프렉터 보다 설계한 PRR-S이 높은 RCS를 나타냈다.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2007년도 Proceedings of ISRS 2007
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• pp.254-257
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• 2007

This paper presents an examination of the spatial integration method for extracting the RCS of a trihedral corner reflector from SAR images for SAR external calibration. An exact external radiometric calibration technique is required for extracting an exact calibration constant. Therefore, we examine the accuracy of the spatial integration method, which is commonly used for the SAR external radiometric calibration. At first, an SAR image for a trihedral corner reflector is simulated with a high-resolution SAR impulse response with a known theoretical RCS of the reflector, and a background clutter image for the high resolution SAR system is also generated. Then, a SAR image in a high resolution is generated for a trihedral comer reflector located on a background clutter by superposition of the two SAR images. The radar cross section of a trihedral corner reflector in the SAR image is retrieved by integrating the radar signals of the pixels adjacent to the reflector for various size of the integration area. By comparison of the measured RCS by the integration method and the theoretical RCS of the reflector, the effect of the size of the integration area on the extraction of the calibration constant is examined.

• International Journal of Aeronautical and Space Sciences
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• 제17권2호
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• pp.253-259
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• 2016

The typical method for performing an absolute radiometric calibration of a Synthetic Aperture Radar (SAR) System is to analyze its response, without interference, to a target with a known Radar Cross Section (RCS). To minimize interference, an error-free calibration site for a Corner Reflector (CR) is required on a wide and flat plain or on an area without disturbance sources (such as ground objects). However, in reality, due to expense and lack of availability for long periods, it is difficult to identify such a site. An alternative solution is the use of a Triangular Trihedral Corner Reflector (TTCR) site, with a surrounding protection wall consisting of berms and a hollow. It is possible in this scenario, to create the minimum criteria for an effectively error-free site involving a conventional object-tip reflection applied to all beams. Sidelobe interference by the berm is considered to be the major disturbance factor. Total interference, including an object-tip reflection and a sidelobe interference, is analyzed experimentally with SAR images. The results provide a new guideline for the minimum criteria of TTCR site design that require, at least, the removal of all ground objects within the fifth sidelobe.