• Journal of Astronomy and Space Sciences
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• 제23권1호
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• pp.19-28
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• 2006

The noise temperature of existing millimeter-wave receivers is already within two or three times quantum noise limit. One of practical ways to increase the observation speed of single dish radio telescope without longer integration time is use of multi-beam focal plane array receiver as demonstrated in several large single dish radio telescopes. In this context the TRAO (Taeduk Radio Astronomy Observatory), which operates a 143n Cassegrain radio telescope, is planning to develop a 4 x 4 beams focal plane array SIS receiver system for 86-115 GHz band. Even though millimeter-wave HEMT LNA-based receivers approach the noise temperature comparable to the SIS receiver at W-band, it is believed that the receiver based on SIS mixer seems to offer a bit more advantages. The critical part of the multi-beam array receiver will be sideband separating SIS mixers. Employing such a type of SIS mixer makes it possible to simplify the quasi-optics of receiver. Otherwise, an SSB filter should be used in front of the mixer or some sophisticated post-processing of observation data is needed. In this paper we will present a preliminary design concept and components needed for the development of a new 3 mm band multi-beam focal plane array receiver.

• ETRI Journal
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• 제33권2호
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• pp.176-183
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• 2011

This paper presents a new analytical approach and experimental verification for the improvement of noise performance in phased-array receivers. For analysis purposes, a multi-channel array system is converted into an equivalent single-channel system, such that the two presents the identical signal and noise powers at the output, respectively. We define an effective gain, noise figure, and signal-to-noise ratio in the equivalent system. Through the proposed approach, the noise performance of the array receiver is analyzed in a general and straightforward manner and then compared to that of each individual array channel. In addition, the phase noise of the array system is analyzed in a rigorous manner, showing its effective reduction by a factor of the array size. The predicted improvement of the noise performance is experimentally confirmed with a CMOS integrated phased-array receiver.

• 한국위성정보통신학회논문지
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• 제12권2호
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• pp.65-70
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• 2017

The structure of MMSE receiver front-ended by CMA(Constant Modulus Array) array working in CDMA forward link which is applicable to LEO spread spectrum satellite communication system is proposed. By using the despreaded pilot signal of forward link as a reference signal, the CMA array can capture multi-path signals securely even in severely faded LEO satellite channel. The remaining MAI (Multiple Access Interference) is cancelled by the cascaded MMSE receiver. Besides theoretical development, through relevant computer simulation, it is proved that the proposed system shows much better BER performance than any other possible candidate systems. As a spatio-temporal receiver mounted on a mobile vehicle, the proposed system also reduces implemental cost and complexity by adopting the simplest algorithm for its spatial and temporal domain processing.

• 한국항행학회논문지
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• 제16권6호
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• pp.952-959
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• 2012

이 논문에서 우리는 송신기와 수신기에 각각 등간격 선형 어레이 (ULA : Uniform Linear Array)와 등간격 원형 어레이(UCA : Uniform Circular Array)를 사용하는 MIMO (Multiple Input Multiple Output) 레이더 시스템을 위한 ESPRIT (Estimation of Signal Parameter via Rotational Invariance Technique) 알고리듬 기반 표적 위치 추정 기법을 제안한다. 수신 안테나가 등간격 선형 어레이인 경우의 ESPRIT과 달리 등간격 원형 어레이인 경우 부어레이의 수신 신호 벡터 간 순환 불변성 (Rotational Invariance)이 만족하지 않는다. 이를 해결하기 위한 연구가 진행되었으나 송신각 추정 문제는 고려되지 않았다. 이 논문에서는 송신 안테나와 수신 안테나를 모두 고려한 ESPRIT 알고리듬을 제안하여 송신 고도각, 수신 고도각, 그리고 수신 방위각을 동시에 추정하는 방법을 소개하고자 한다.

• 한국군사과학기술학회지
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• 제14권5호
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• pp.825-832
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• 2011

In this paper, we described the design and measurement results of a Front-End Receiver for S-band active phased array radar. The Front-End Receiver has input P1dB of -4dBm and IIP3 of 7dBm. The measurement results show that gain is $24{\pm}0.7dB$, noise figure are less than 2.3dB over the frequency range of $fc{\pm}0.2GHz$. The Front-End Receiver can protect the receiver path from large input signals with a maximum peak power of multi-kW and recovery time is less than 0.8us. The measurement results satisfy all specifications.

• 한국전자파학회:학술대회논문집
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• 한국전자파학회 2003년도 종합학술발표회 논문집 Vol.13 No.1
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• pp.219-223
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• 2003

This paper describes an estimation of DOA(Direction Of Arrival) measurement system using DBF receiver with linear array antenna. This DBF receiver is composed of resistive FET mixer using low IF mettled. A radio frequency(RF), a local oscillator(LO) and ail intermediate frequency(IF) considered in this research are 2.09 GHz, 2.08 GHz and 10 MHz, respectively. This receiver is composed of a band-pass filter, a low-pass filter, a DC bias circuit. DOA measurement system is consist of linear array antenna, DBF receiver, AD control box and computer in the anechoic chamber. Receiving antenna is 4-array monopole antenna and DBF receiver is 4-Ch resistive FET mixer without amplifier. DOA algorithm is implemented using MUSIC algorithm with high resolution. We show that the results of DOA is $-30^{\circ},\;0^{\circ}$ and $60^{\circ}$, respectively. And we know that DOA estimation error occur by antenna radiation pattern and fabrication error of antenna array.

• 한국전자파학회논문지
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• 제22권3호
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• pp.371-379
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• 2011

최근의 다기능 레이더는 능동 위상 배열 안테나 구조를 이용하고 있다. 열약한 클러터 환경에서 표적을 탐지하기 위해서는 레이더 수신기의 동적 영역이 커야 한다. 능동 위상 배열 안테나 구조를 이용한 구조의 레이더는 SNR(Signal-to-Noise Ratio)를 향상시키지만, SFDR(Spurious Free Dynamic Range)은 개선되지 않는다. 본 논문에서는 높은 SFDR을 갖는 X-밴드 능동 위상 배열 레이더의 다채널 디지털 수신기를 설계하고 제작하였다. 32개의 T/R(Transmit/Receive) 모듈이 한 채널의 디지털 수신기와 연결되어 있다. 디지털 수신기내에 RF부, ADC부, 로컬 분배부 및 디지털 하향변환부가 존재하고, 한 개의 조립체 내에 2채널의 디지털 수신기가 포함되어 있다. 상용 FIFO 보드를 이용하여, 디지털 출력 신호에 대해, 디지털 수신기 주요 특성을 측정하였다. 제작된 디지털 수신기의 이득은 33 dB이고, SFDR은 81 dBc 이상이다.

• 전자공학회논문지
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• 제52권5호
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• pp.10-22
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• 2015

이최근, 3GPP (3rd Generation Partnership Project) 에서는 폭발적으로 증가하고 있는 모바일 데이터 트래픽을 수용하기 위하여 사이드홀 (Sidehaul) 시스템을 개발하고 이에 대한 연구가 활발히 진행되고 있다. 사이드홀 시스템은 낮은 PAPR (Peak to Average Power Ratio)을 위해 SC-FDMA (Single Carrier-Frequency Division Multiple Access)를 기반으로 한다. 또한 제한된 공간에서 안테나 배열을 사용함으로써 MIMO (Multiple Input Multiple Output) 전송이 가능하게 한다. 본 논문에서는 사이드홀 시스템에서 ULA (Uniform Linear Array), UCA (Uniform Circular Array) 및 UPA (Uniform Planar Array)에 대한 안테나 배열을 설계하고 성능을 분석한다. 또한, 이웃셀로 부터 간섭의 영향을 줄이기 위하여 새로운 하이브리드 수신기 FSC(Full Suppression Cancellation)를 제안한다. 제안한 수신기는 IRC (Interference Rejection Combining)와 SIC (Successive Interference Cancellation)를 결합하여 간섭을 억제 및 제거 할 수 있다.

• 천문학회지
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• 제38권2호
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• pp.103-106
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• 2005

The Submillimeter Array (SMA), a collaborative project of the Smithsonian Astrophysical Observatory (SAO) and the Academia Sinica Institute of Astronomy & Astrophysics (ASIAA), has begun operation on Mauna Kea in Hawaii. A total of eight 6-m radio telescopes comprise the array with currently working receiver bands at 230, 345, and 690 GHz. The array will have 8 receiver bands covering the frequency range of 180-900 GHz. The backend is flexible analog-digital correlator with a full bandwidth of 2GHz, which is very powerful to cover several line emissions simultaneously. The current status and future plans of the SMA are described with emphasis on Taiwanese efforts.

• ETRI Journal
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• 제26권6호
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• pp.605-614
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• 2004

In this paper, we investigate array calibration algorithms to derive a further improved version for correcting antenna array errors and RF transceiver errors in CDMA smart antenna systems. The structure of a multi-channel RF transceiver with a digital calibration apparatus and its calibration techniques are presented, where we propose a new RF receiver calibration scheme to minimize interference of the calibration signal on the user signals. The calibration signal is injected into a multi-channel receiver through a calibration signal injector whose array response vector is controlled in order to have a low correlation with the antenna response vector of the receive signals. We suggest a model-based antenna array calibration to remove the antenna array errors including mutual coupling errors or to predict the element patterns from the array manifold measured at a small number of angles. Computer simulations and experiment results are shown to verify the calibration algorithms.