• Journal of Positioning, Navigation, and Timing
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• v.9 no.1
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• pp.7-13
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• 2020

As a countermeasure against the threat of jamming which can disrupt operation of the Global Positioning System (GPS) receivers, various kinds of technique to estimate the Direction-Of-Arrivals (DOAs) of incoming jamming signals have been widely studied, and among them, the MUltiple SIgnal Classification (MUSIC) algorithm is known to provide very high resolution. However, since the previous studies regarding the MUSIC algorithm does not consider the orientation of each antenna element of antenna arrays, there is a possibility that DOA estimation performance degrades in the case of a misaligned antenna array whose antenna elements are not oriented along the same direction. As an effort to solve this problem, there exists a previous work which presents an MUSIC-based method for DOA estimation. However, the error between the real and measured values of each antenna orientation is not taken into consideration. Therefore, in this paper, the effect of the aforementioned error on the DOA estimation performance in the case of a misaligned antenna array is analyzed by simulations.

• Journal of Positioning, Navigation, and Timing
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• v.13 no.3
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• pp.277-287
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• 2024

In satellite systems, efficient communication and observation require identifying of specific signal arrival points using onboard antenna systems. When utilizing massive array antennas to estimate the angle of arrival (AOA) of signals, traditional high-performance AOA estimation algorithms such as Multiple Signal Classification (MUSIC) encounter extremely high complexity due to the numerous individual antenna elements. Although, in order to improve this computational complexity problem, the cascade AOA estimation algorithm with CAPON and beamspace-MUSIC was recently proposed, the comparison of the computational complexity of the proposed algorithm across different massive array antenna configurations has not yet been conducted. In this paper, we provide the analyzed results of the computational complexity of the proposed cascade algorithm based on various massive array antennas, and determine an optimal antenna configuration for the efficient AOA estimation in satellite systems.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.42 no.1
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• pp.91-97
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• 2005

In the mobile antenna systems for satellite multimedia communications, the active way antenna having a low sidelobe antenna pattern is described in this paper. This designed and fabricated array antenna is satisfied with international beam pattern regulation on moving states. The subarray of the proposed mobile antenna system is arranged with a stair-planar structure and non-periodic array spacing. This subarray is designed with three-layered microstrip patch as both receiving and transmitting radiator of which are improved with antenna gain and bandwidth. Also, the optimum subarray spacing is designed to make the lowest sidelobe pattern by genetic algorithm. In addition, the characteristics of a GA-perturbed array are investigated from simulated and measured beam pattern results.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.32 no.8C
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• pp.745-757
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• 2007

In this paper, we propose a design of GPS anti-jamming system and its operational method, which can effectively suppress interference and jamming signals induced in GPS receiver. The 7-array antenna used in the proposed system is composed of conventional 6 equi-spaced circular elements with one element on the center of antenna and can be efficiently operated under power-constrained conditions. Futhermore, in this paper, we analyze the structure and complexity of STAP and SFAP which are well known techniques in adaptive array antenna signal processing, and we compare the BER performances between STAP and SFAP in various jamming environment based on the same complexity.

• Journal of Korea Society of Digital Industry and Information Management
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• v.10 no.4
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• pp.63-70
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• 2014

Method a target estimation in spatial are mobile wireless communication using network cell and GPS. It have much error that mobile wireless communication depend on cell size. GPS method can't find a target in shadow and inner area. In this paper, we estimate a target as direction of arrival method using adaptive array antenna system. Adaptive array antenna system can obtain desired signal to remove other signal This paper studied digital beamforming method in order to estimation a target. Proposed method is modified optimum weight and antenna error correction to estimation an optimal receive signal. Digital beamforming method decided a signal phase and amplitude from received signal on array antenna element. But if it is not to do error correction of received signal, system performance have decreased. Firstly, we proposed modified optimum weight in order to finding desired target. Secondly, we are error correction of antenna incident signals by optimal weight before digital beamforming method. Thirdly, throughly simulation, we showed that system performance of proposed method compare proposal method with general method. It have improved resolution of estimation target to good performance more proposed method than general method.

• Proceedings of the IEEK Conference
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• 2002.07b
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• pp.1354-1357
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• 2002

In this paper, we propose a suboptimal receiver combining adaptive array antenna and orthogonal decision-feedback detector in DS/CDMA system. Adaptive array antenna can cancel out undesired signal using beamforming scheme. However, if there are interfering signals from undesired users with the same incident angle as that of a desired user, an adaptive array antenna cannot suppress them. The proposed receiver can cancel out remaining interference from users having nearly the same beam pattern. And we employ Orthogonal Decision-Feedback Detector (ODFD) as multiuser detection. The ODFD performs as good as the decorrelating decision -feedback detector (DDD) with much less complexity. Simulation results show that the proposed system provides a significantly enhanced performance.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 1999.11a
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• pp.120-123
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• 1999

This paper presents the design method of EMC(Electromagnetic Coupling) microstrip array antenna for CS(Communication Satellite) system. Microstrip dipole antennas are attractive elements owing to the desirable properties such as simplicity, small size and linear polarization. From the optimum simulation results by the FDTD method[1], design parameters such as EMC dipole length, width, height and offset are discussed at 12CHz. The array characteristics of 5-elements and 10-elements array are also presented. By adjusting geometry of model antenna, we can design dual polarization EMC microstrip dipole antenna for CS system. Direction of nam beam is easily tilted by the control of distance between dipole elements.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.23 no.1
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• pp.29-37
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• 2012

In this paper, a stabilizd system operation through a composition of a protective circuit and an improvement of active reflection coefficient(ARC) is studied. Unlike the passive-phased array antenna, the APPA is a combined form of radiating element and transmitter-reciever module. Therefore, a definition of new ARC that differentiates itself from typical passive-phased array antenna must apply. The ARC is a reflection coefficient considering a superposition of a coupling from nearby radiating elements and self reflection. It is an important parameter that predicts and analyzes charateristics of a APPR system. A high level ARC is a direct source inducing a performance degradation of a system. In this paper, as a method for a stabilized operation of APAR, one method for improving a performance and another for degradation prevention are analyzed. An effectiveness of two methods was validated using experiment results of real-fabricated active-phased array antenna.

• Proceedings of the Korea Institute of Applied Superconductivity and Cryogenics Conference
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• 2003.10a
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• pp.294-297
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• 2003

In this paper we designed and measured HTS antenna array for Direct Broadcast Satellite (DBS) system. HTS antennas fabricated in this work were a four-element, 11.67 ㎓z, high-Tc superconducting (HTS) microstrip antenna array with corporate feed network and circular polarization for direct broadcas- ting satellite (DBS) system. Our antennas was designed and built on a 0.5 mm thick YBa2Cu3O7-x (YBCO) /MgO substrate. The measurement results showed good axial ratio, wide bandwidth a remarkable improvement over their metal counterpart.

• Proceedings of the IEEK Conference
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• 2003.11c
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• pp.396-402
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• 2003

본 논문에서는 multi-media service를 제공하는데 smart antenna system을 적용했을 때의 performance 를 각 서비스별 특성에 따라 평가한다. 서로 다른 다중 rate 의 신호가 각각의 안테나를 통해서 수신되는 환경 하에서 adaptive smart antenna를 적용함으로써 보다 고속이고 향상된 용량의 서비스를 제공할 수 있도록 하기 위해서는 사용자의 지리적 분포 또는 간섭 전력에 따라서 성능 특성이 달라지므로 이에 대한 성능 분석을 시뮬레이션을 통해서 수행한다.