• 한국전기전자재료학회논문지
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• 제17권7호
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• pp.770-775
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• 2004

Although $High-T_c $superconducting HTS antennas have high efficiency and high gain, narrow bandwidth due to the high Q is the major limitation for application of satellite communication and mobile communication. Defining bandwidth as the frequency range over which standing wave ratio (SWR) is 2:1 or less, HTS antenna bandwidths are typically less than 1 %. Thus considerable effort has been focused on developing HTS antennas for broadband operation. In this work the HTS antenna array, using the bipin antenna which consisted of two triangle-radiation patches, was designed and fabricated using a ${YBa}_2{Cu}_3{O}_7x (YBCO)$ superconducting thin film on a MgO substrate for broadband operation. Also gold antennas with the same dimension as our HTS antennas were fabricated on the MgO substrate for the comparison. Experimental results for both antennas were reported in terms of radiation patterns, return losses, bandwidths and other various characteristics. The center frequency of HTS antennas was 20.28 GHz and the bandwidth obtained was significant 10 %.

• 전자공학회논문지
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• 제49권10호
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• pp.47-53
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• 2012

시간 반전 (time-reversal, TR) 전처리 기법은 유효 채널의 전력을 특정 시간으로 집중시키는 역할을 하며, 이를 통해 단일 탭 수신기의 수신 성능을 향상시킬 수 있다. 선형 블록 전처리 형태를 가지는 주파수 영역 동일 이득 결합 (frequency-domain equal-gain-combining, FD-EGC) TR 기법은 기존의 TR 기법에 비해 temporal focusing 성능이 뛰어나다. 또한, FD-EGC는 분산 안테나 시스템 (distributed antenna systems, DAS)에서 minimum mean square error 수신기의 수신 성능을 향상시킨다. 본 논문에서는 이러한 FD-EGC의 수신 성능 분석에 그치지 않고, capacity 성능을 분석하는 것에 중점을 두었다. 우선, DAS에서 FD-EGC의 capacity를 유도하였으며, 안테나 수에 따라 capacity가 증가함을 보였다. 이어 정보 이론적 보안 측면에서 secrecy rate를 유도하였으며, 이를 통해 FD-EGC가 다른 사용자에게 보안을 유지하면서도 목표 사용자에게는 많은 양의 정보를 전송할 수 있음을 보였다.

• 한국정보통신학회:학술대회논문집
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• 한국정보통신학회 2017년도 춘계학술대회
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• pp.59-60
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• 2017

본 논문에서는 변형된 밸런, 한 개의 도파기, 두 개의 기생 패치를 이용하여 이중 직렬-급전 다이폴 쌍 안테나(series-fed dipole pair antenna; SDPA)의 대역폭과 이득을 향상시키는 방법에 관하여 연구하였다. 제안된 SDPA는 두 개의 서로 다른 길이의 스트립 다이폴 안테나, 접지 반사기, 한 개의 도파기, 두 개의 기생 패치로 구성된다. 대역폭을 늘리기 위해 변형된 밸런을 사용하였고, 중간 및 고주파수 대역에서 이득을 높이기 위해 한 개의 도파기와 두 개의 기생 패치를 추가하였다. 최종설계된 SDPA를 FR4 기판 상에 제작하고 특성을 실험한 결과 전압 정재파비(voltage standing wave ratio; VSWR)가 2 이하인 대역은 1.56-3.10 GHz이고, 1.55-3.00 GHz 대역에서 이득이 7dBi 이상을 유지하는 것을 확인하였다.

• 한국정보통신학회논문지
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• 제23권12호
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• pp.1659-1665
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• 2019

본 논문에서는 WLAN (wireless local area network) 응용을 위한 소형 인쇄형 모노폴 안테나의 새로운 설계에 대해 연구했다. 선폭이 다른 패치와 계단 모양의 접지면이 있는 복사체는 안테나 크기를 줄이기 위해 사용된다. 안테나의 크기는 16 × 17 × 1 ㎣이며 포토리소그래피(photolithography) 기술로 제작되었다. 시뮬레이션 및 측정 결과가 잘 일치한다. 연구된 안테나의 공진 주파수는 약 5.2 GHz이며 측정 결과 1 GHz의 임피던스 대역폭을 가진다. 또한 측정된 방사패턴을 제시하고 필요한 WLAN 5 GHz 주파수 대역 (5.15 - 5.825 GHz)에서 측정된 이득 및 효율을 제시했으며, 5 GHz 대역 WLAN 안테나로 사용할 수 있음을 확인했다. 연구된 안테나는 소형, 경량, 저비용, 전방향성 복사패턴, 고이득 및 고효율을 갖는다.

• Journal of Electrical Engineering and Technology
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• 제8권4호
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• pp.850-855
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• 2013

This paper proposes a novel design for a compact, high-isolation WCDMA indoor repeater antenna. The proposed antenna consists of a patch antenna and metamaterial absorber. The required WCDMA bandwidth is obtained by utilizing the coupling between the main and the parasitic patches. In addition, high isolation is achieved using the metamaterial absorber, which has an absorption of about 98% at 2.1 GHz. Overall, the proposed antenna has a gain of over 7 dBi, a Voltage Standing Wave Ratio (VSWR) of less than 2, more than 85 dB of isolation between the service and donor antennas over the WCDMA band and a total volume of the proposed antenna only $70mm{\times}70mm{\times}43.8mm$.

• Journal of information and communication convergence engineering
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• 제6권4호
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• pp.391-395
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• 2008

Wideband terminal and base station is required to serve not only existing 1st and 2nd generation mobile communication systems but also 3rd generation systems. In this paper, we present a feasibility study on coaxial feed compact wideband antenna for UHF RFID reader application. The original antenna was designed for partial discharge detection sensor in high voltage diagnostic system. However, we modified the original prototype to achieve shifted down resonant frequency for wideband wireless communication applications. The experimental result shows good return loss characteristics and radiation patterns except for the total gain at each resonant frequency. The maximum measured gain was 2.45 dBi$\sim$3.18 dBi at 910MHz.

• Journal of information and communication convergence engineering
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• 제9권5호
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• pp.483-486
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• 2011

In this study, a fan-beam microstrip array antenna for an X-band radar was designed and fabricated using a novel technique. A microstrip array structure was used to obtain a high-gain and narrow horizontal beam-width. The feeding point is located at the center of the antenna because of its $360^{\circ}$ rotational characteristic. The measured results indicate a gain of 23dBi, and a horizontal and vertical beamwidth of $3.57^{\circ}$, $26.12^{\circ}$, respectively. The proposed antenna performed adequately and managed to meet the specifications.

• Journal of information and communication convergence engineering
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• 제6권2호
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• pp.164-168
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• 2008

Wideband terminal and base station is required to serve not only existing 1st and 2nd generation mobile communication systems but also 3rd generation systems. In this paper, we presents a feasibility study on single feed compact wideband antenna for wireless communication applications including GSM (890-960 MHz), GPS (1575 MHz), DCS (1710-1880 MHz), PCS (1880-1990 MHz), UMTS (1900-2200 MHz), ISM (2400-2480 MHz), IMT2000 and satellite DMB bands. The original antenna was designed for partial discharge detection sensor in high voltage diagnostic system. However, we modified the original prototype to achieve shifted down resonant frequency for wideband wireless communication applications. The experimental result shows good return loss characteristics and radiation patterns except for the total gain at each resonant frequency. The maximum measured gain was 2.45 dBi${\sim}$3.18 dBi at 1710 MHz${\sim}$1880 MHz.

• ETRI Journal
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• 제22권1호
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• pp.12-19
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• 2000

Wireless communication systems using airship have been proposed in worldwide. The airship will be located at the stratosphere about $20{\sim}23\;km$ above the sea level. The position of airship will vary within the station keeping range with time due to the drag of the wind in the stratosphere. When the earth station antenna has a high gain without the tracking function, the antenna performance may be degraded by a small variation of the airship. This means that variation of airship location could result in serious degradation of the system performance. In this paper, degradation in earth station's Equivalent Isotropic Radiated Power (EIRP) and Gain to noise Temperature ratio (G/T) due to the stratospheric platform movements has been derived by calculating the deviation angle of the main beam directions between the earth station and the platform antenna. In this case, the antenna of the earth station has been assumed circular and/or patch array antennas.

• 한국전자파학회:학술대회논문집
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• 한국전자파학회 2000년도 종합학술발표회 논문집 Vol.10 No.1
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• pp.341-344
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• 2000

There are many researches to increase bandwidth of the microstrip patch antenna for wireless LAN. In spite of broad bandwidth, Bow-Tie microstrip patch antenna, broadband microstrip patch antenna, has disadvantages that are low gain and big size. In this paper, stacked Bow-Tie microstrip patch antenna for wireless LAN is designed in 5.725～5.825GHz band. This antenna has characteristics that are broadband bandwidth, high gain and small size compared with microstrip patch antenna. In simulated results, the return loss is -34.2dB at 5.78GHz and bandwidth is 11.345% for VSWR is 2:1 and 7.75% for VSWR is 1.5:1. In measured results, the return loss is -38-45dB at 5.78GHz and bandwidth is 13% for VSWR is 2:1 and 5.6% for VSWR is 1.5:1.