• Journal of electromagnetic engineering and science
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• 제17권2호
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• pp.108-110
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• 2017

The global positioning system (GPS) is a useful system in civilian and military applications. However, because of the weak signal, GPS receivers are vulnerable to interference caused by unwanted signals or intentional jammers. To alleviate this issue, a controlled reception pattern antenna (CRPA) array can be employed to adaptively place radiation pattern nulls toward the direction of the signal interference. The performance of the CRPA array improves as the number of antenna elements increases. Therefore, antenna miniaturization is highly desirable for CRPA applications. We designed a compact CRPA array based on seven electrically miniaturized microstrip patch antennas (MPAs) on a 5-inch ground platform. We used a non-Foster matching circuit to match efficiently miniaturized MPAs on an FR-4 substrate. Experimental results show that the non-Foster matching circuit significantly improves such elements of antenna performance as return loss and antenna gain. In addition, we confirmed that the mutual coupling of the proposed CRPA array is less than -45 dB.

• Journal of electromagnetic engineering and science
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• 제16권2호
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• pp.74-79
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• 2016

This paper proposes an optimum array configuration to improve null steering time for mobile controlled reception pattern antenna (CRPA) systems. The proposed array consists of a single reference element at the center and nine auxiliary elements arranged in a circular array. The array radius and the vertical positions of the center element are optimized using a genetic algorithm in conjunction with a constrained least-mean-square algorithm. The results demonstrate that the proposed array is suitable for mobile CRPA systems without significant side nulls in satellite directions.

• 한국군사과학기술학회지
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• 제9권3호
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• pp.48-55
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• 2006

This paper describes the antenna based GPS anti-jamming technology called CRPA(Controlled Reception Pattern Antenna), which used $2{\times}2$ array elements. In this system, the main functions are the antenna complex weight control and the GPS digital I/Q VM(Vector Modulator). To update the VM's I/Q complex weights, the PC based DAC(Digital to Analog Converter) module was also used and the two analog output voltages were applied to the $2{\times}2$ array elements to synthesize the null pattern. In the study, we also simulated the $2{\times}2$ GPS array null patterns to compare the null depth with experimental results. The VM was also modified at the frequency of 1.575GHz for the GPS L1 and controlled by the PC based VM software.

• Journal of electromagnetic engineering and science
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• 제18권2호
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• pp.129-135
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• 2018

This paper proposes a design of small controlled reception pattern antenna (CRPA) arrays using circular microstrip loops with frequency-insensitive characteristics. The proposed array consists of seven identical upper and lower circular loops that are electromagnetically coupled, which results in a frequency-insensitive behavior. To demonstrate the feasibility of the proposed feeding mechanism, the proposed array is fabricated, and its antenna characteristics are measured in a full-anechoic chamber. The operating principle of the proposed feeding mechanism is then interpreted using an equivalent circuit model, and the effectiveness of the circular loop shape is demonstrated by calculating near electromagnetic fields in proximity to the radiator. The results confirm that the proposed feeding mechanism is suitable to have frequency-insensitive behavior and induces strong electric and magnetic field strengths for higher radiation gain in extremely small antenna arrays.

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2006년도 International Symposium on GPS/GNSS Vol.2
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• pp.411-414
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• 2006

본 논문은 다양한 GPS 재밍대응 기술 중에서 안테나 기반의 CRPA(Controlled Reception Pattern Antenna) 시스템에 관한 소개 및 안테나의 널(null) 패턴 합성에 필요한 핵심 모듈인 디지털 I/Q 벡터모듈레이터(Vector Modulator)를 이용한 GPS용 $2{\times}2$ CRPA 패턴 제어방법에 관한 연구 내용이다. 일반적으로 시스템에서 미리 결정된 방향으로 만들어진 안테나 빔을 이용한 위상배열안테나(phased array antenna)와는 달리 CRPA 구조의 GPS 위성수신용 적응배열안테나(adaptive array antenna)는 각 안테나 소자(element)로부터 수신된 신호들을 실시간으로 해석하여, GPS 배열 안테나의 패턴 특성을 제어한다. 본 연구에서는 $2{\times}2$ 배열 정사각(square) 구조의 CRPA를 채택했으며, 재밍신호 방향으로 널(null) 패턴을 합성하기 위한 방법으로 PC에서 제어 가능한 DAC(Digital to Analog Converter)을 이용하여 I/Q 벡터모듈레이터로 인가되는 RF신호의 위상(phase) 및 진폭(amplitude)을 조절한다. 이때 원하는 널(null) 패턴이 합성되도록 네 개의 각 안테나 소자 쪽으로 8채널의 복소가중치(complex weight)를 인가한다.

• 한국위성정보통신학회논문지
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• 제12권2호
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• pp.83-88
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• 2017

본 논문에서는 저고도각 고이득 특성을 이용한 3 소자 CRPA 배열 안테나 설계를 제안하였다. 제안된 안테나는 급전패치와 방사패치로 구성되어 있으며, 급전패치에 동축케이블을 통해 급전부가 직접 연결되고 방사패치에 전자기적으로 간접급전되어 저고도각 이득 특성이 개선되는 구조를 가진다. 제안된 배열안테나의 성능 측정을 전파무반사실에서 수행하였으며, 전면 방향 이득은 2.8 dBic, 축비 특성은 2.7 dB, $75^{\circ}$의 저고도각 평균 이득이 -1.4 dBic를 나타내어 항재밍 성능을 갖는 CRPA 안테나로 적합함을 확인하였다.

• Journal of Electrical Engineering and Technology
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• 제13권5호
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• pp.2045-2049
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• 2018

An antenna arrays for a satellite navigation systems require more antenna elements to mitigate multiple jamming signals. In order to maintain the small array size while increasing the number of antenna elements, miniaturization technique is essential for antenna design. In this work, an electrically small circular microstrip patch antenna with a 3 dB hybrid coupler is designed as an element antenna, where the 3 dB hybrid coupler can yield the circularly polarized radiation characteristic. The miniaturized element antenna typically has too large capacitance in GPS L1 and GLONASS G1 bands, making it difficult to match with a single stand-alone non-Foster matching circuit (NFMC) in a stable state. Therefore, we propose a new matching technique, referred to as the hybrid matching method, which consists of a NFMC and a passive circuit. This passive tuning circuit manages reactance of antenna elements at an appropriate capacitance without a pole in the operating frequency range. The antenna array is fabricated, and the measured results show a reflection coefficient of less than -10 dB and an isolation of greater than 50 dB. In addition, peak gain of the proposed antenna is increased by 22.3 dB compared to the antenna without the hybrid matching network.

• 한국전자파학회논문지
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• 제25권6호
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• pp.628-636
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• 2014

본 논문은 재밍 대응 위성 항법 장치의 5소자 평면 배열 안테나 설계에 대해 기술한다. GPS $L_1/L_2$ 대역에서 공진하는 적층 구조의 패치 안테나 설계를 제안한다. 제안된 안테나는 광대역 및 원형 편파 특성을 구현하기 위해 칩 커플러를 이용한 이중 급전을 사용한다. 배열안테나 측정 결과, 중앙안테나의 전면 방향 이득은 $L_1$과 $L_2$ 대역에서 각각 1.10 dBic, 0.37 dBic, 측면안테나는 $L_1$과 $L_2$ 대역에서 0.99 dBic, -0.57 dBic를 갖는다. 고각 $30^{\circ}$에서 방위각의 이득은 중앙안테나 $L_1$과 $L_2$ 대역에서 평균 -2.08 dBic, -5.33 dBic의 측정 결과를 갖는다. 측면안테나는 $L_1$과 $L_2$ 대역에서 평균 -0.40 dBic, -2.09 dBic의 측정 결과를 갖는다. 제안된 5소자 평면 배열 안테나는 GPS 재밍 대응 장치에 적합함을 확인한다.