• Journal of the Institute of Electronics Engineers of Korea TC
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• v.45 no.8
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• pp.15-27
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• 2008

In this paper, an EBG(Electromagnetic BandGap) resonator antenna with a stripline type FSS(Frequency Selective Surface) superstrate for PCS-band base station antennas is proposed. The characteristics of resonant frequency and -3dB bandwidth of a unit cell of a superstrate are first analyzed by varing several design parameters such as a strip width and a unit cell width in order to design an EBG resonator antenna satisfying the required antenna gain and bandwidth for PCS-band base station antennas. Among various unit cell shapes, strip dipole and stripline are considered and their characteristics are compared. It was found that a resonant length of the EBG resonator antenna becomes smaller when the stripline shape is used and the control of the bandwidth is also much easier. By using the unit cell simulation results, planar and cylindrical EBG resonator antennas at PCS-band are designed.

• Proceedings of the KIEE Conference
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• 2003.07c
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• pp.1984-1986
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• 2003

본 논문은 UWB(Ultra WideBand) 기술에 기반한 지반탐사레이더(Ground Penetrating Radar, GPR)용으로 개발된 광대역 안테나의 특성에 관해 나타낸다. UWB 기술의 핵심은 주기가 수 나노초 이하의 짧은 임펄스를 이용하는 것으로 지반탐사레이더는 이 임펄스 기술을 이용함으로서 탐사 능력과 해상도를 높일 수 있다. 임펄스 전송을 위해 안테나는 넓은 대역폭, 크기, 무게, 가격 등 지반탐사레이더에 적용될 수 있는 조건을 만족해야 함으로 안테나의 설계는 이에 부합할 수 있는 다이폴 안테나를 선택하여 개발하였다. 개발된 안테나의 성능을 검증하기 위해 시뮬레이션과 실험을 실시하였고 그 결과 설계된 안테나의 대역폭이 0.5 GHz에서 2.7 GHz로 2.2 GHz(138%)의 사용대역을 나타냄으로서 UWB 기술에 기반한 지반탐사레이더용으로 유용함을 확인하였다.

• KOREAN POULTRY JOURNAL
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• v.17 no.12 s.194
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• pp.30-32
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• 1985

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.47 no.7
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• pp.85-92
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• 2010

In this paper, we consider the orthogonal frequency division multiplexing (OFDM) based transmission incoorperating with beam-switching and space-time coding. Specifically, we consider three configurations; (1) the beamforming technique, (2) the spatial diversity technique and (3) their combination and evaluate the performance in wireless personal area network (WPAN) environment. For the beam-forming technique, we consider the beam-switching which is performed at RF front-end with a pre-defined set of beams and for the space-time coding, we consider the Alamauti scheme with antenna selection. For the combined scheme, we divide the antennas used into two group to generate two independent beams and apply the two-antenna Alamauti scheme over the two beams. For these three configurations, performance is evaluated in terms of the SNR gain.

• Proceedings of the Korea Society for Industrial Systems Conference
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• 2004.06a
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• pp.125-130
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• 2004

무선 및 이동 통신에 있어 2.4 GHz 대역은 허가 없이 사용할 수 있는 ISM (Industrial Scientific Medical) 주파수 밴드로 다양한 무선통신시스템에 사용되고 있다. 그러나 송출 전력을 제한하고 있어 전파환경 등에 의해 통화품질이 저하되는 경우가 많이 발생한다. 이와 같은 통신의 저하 요소를 해결하는 방법중의 하나로는 이득이 높은 안테나의 사용을 들 수 있다. 본 논문은 2.4 GHz 대역에 있어 지향성 이득이 큰 마이크로스트립 안테나를 설계하고, 패치의 배열에 따른 이득의 변화를 제시하여 통신시스템의 용도에 따른 안테나의 적절한 선택기준을 제시한다. 설계한 마이크로스트립 안테나의 특성을 살펴보면 공진주파수 2.45 GHz 에서 입력 임피던스는 약 50 Ω으로 별도의 정합회로가 필요치 않으며, 1개의 패치인 경우 안테나의 이득은 약 6.2 dBi 이고, 패치의 배열에 따라 이득의 증대가 나타났다.

• Journal of Korea Society of Industrial Information Systems
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• v.9 no.2
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• pp.74-80
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• 2004

This paper presents analysis and design for Microstrip antennas using FEM (Finite Element Method). For the miniaturization of the antennas, dielectric substrate (ε/sub r/=4.6) and rectangular patch structure are used. The proposed Microstrip antennas are simulated using commercial simulator (HFSS). The results of the simulation are presented and compared with characteristics of each array type. Especial, the proposed antennas can be applied to the design of various communication systems for 2.4 GHz band.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.25 no.9
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• pp.879-885
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• 2014

In this paper, we designed and fabricated wideband 3-axis isotropic antenna for the Electro-Magnetic Fields(EMFs) measurement. Each part of proposed 3-axis antenna has isotropic characteristics and arbitrary axis of proposed 3-axis antenna could be selectable using RF switch. Also, a resistor was inserted in each axis of proposed 3-axis antenna for improving antenna gain and noise suppression characteristics, and port impedance of each dipole antenna were matched by balun. For the performance verification of antenna, GTEM Cell which generates standard electromagnetic field was used for the derivation of antenna factor and receiver sensitivity. As a result, fabricated 3-axis isotropic antenna has receiver sensitivity of 0.12~4.2 mV/m and typical VSWR of 3.3:1 within a wide operation frequency range from 0.03 MHz to 3 GHz.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.19 no.8
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• pp.927-932
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• 2008

We propose a novel $4{\times}4$ Hadamard matrix feed network for a $4{\times}1$ array antenna to form a dual beam. If each element of the array is excited following the elements in a row of the Hadamard matrix, a two-lobed antenna beam can be obtained. The angle between the two lobes can be controlled. The Hadamard matrix feed network consists of four $90^{\circ}$ hybrids, a crossover and four $90^{\circ}$ phase shifters. The array, including the Hadamard matrix feed network, was fabricated on a microstip structure. The measured beam directions of the two lobes are $0^{\circ}$, ${\pm}15^{\circ}$, ${\pm}33^{\circ}$, ${\pm}45^{\circ}$ depending on the choice of the input port of the feed network.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.2
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• pp.779-783
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• 2012

In this paper, we studied the design and fabrication of $2{\times}2$ array-type microstrip patch antenna to be used in wireless communication systems operating at around 5GHz band. To obtain wide bandwidth and high gain, antenna parameters such as patch size, inter patch space are simulated by HFSS(High Frequency Structure Simulator). From these parameters, the $2{\times}2$ array-type microstrip patch antenna is fabricated using FR-4 substrate. The measured results of the antenna are as follows: The center frequency of 5.06GHz, insertion loss of -44dB, bandwidth of 200MHz, and VWSR of 1.1.

• Journal of Broadcast Engineering
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• v.15 no.2
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• pp.157-162
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• 2010

In this paper, We propose that the adaptive cooperative relay transmission technique using closed-loop MIMO scheme for duplex communication system. As the mobility between relay and base station is little, closed-loop MIMO is better diversity gain than open-loop MIMO. At this time, more than one relaying terminals are included in one cooperative group to share their transmission and take precoding weight feedback. For minimization of throughput reduction caused by increasing feedback bits, we use codebook-based MRT that limit the number of feedback bits. Among the cooperative relay group, the best relays are selected from the base stataion and get the feedback. A protocol senarios are also proposed for this relay system.