• Journal of electromagnetic engineering and science
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• v.13 no.1
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• pp.22-27
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• 2013

This paper describes a wideband double dipole quasi-Yagi antenna fed by a microstrip-to-slotline transition. The transition feed consists of a microstrip radial stub and a slot radial stub, each with the same angle of $90^{\circ}$ but with different radii, to achieve wideband impedance matching. Double dipoles with different lengths are utilized as primary radiation elements to enhance bandwidth and achieve stable radiation patterns. The proposed antenna has a measured bandwidth of 3.34~8.72 GHz for a -10 dB reflection coefficient and a flat gain of $6.9{\pm}0.6$ dBi across the bandwidth.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2003.11a
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• pp.541-545
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• 2003

본 논문에서는 하나의 급전소자와 두개의 무급전 소자로 구성된 전 후방 지향성을 가진 비행체 탑재 능동 빔 조향 프린트형 야기-우다 안테나를 설계, 제작하였다. 제작된 안테나는 두개의 무급전 소자에 부착된 칩다이오드의 간단한 스위칭 작용(Open, Short)으로 지향성 다이버시티를 구현하였다. 그리고 모노폴 급전 소자와 두개의 무급전 소자와의 거리를 변화시켜 상호 임피던스의 영향이 고려된 최대 전.후방비를 찾았다. 중심주파수 1.81 GHz에서 모노폴 급전소자와 무급전소자간의 간격이 $0.25{\lambda}$일 때, 26.6 dB의 최대 전.후방비(Open-Short 또는 Short-Open)특성이 나타내었다. 이를 통해 후방에 있는 지상 통제소와 미사일의 비행 방향에 관계없이 교신 가능한 수신 레벨을 유지 할 수 있음을 확인하였다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.5 no.1
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• pp.76-82
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• 1980

In this paper, an arbitrary Iinear antenna is divided into many small sections and numeral analysis by moment method is carried out. So, the equation which is closed to the actual current distribution and solved easily compared with the induced-emf method or retarded potencial method is derived. The current distribution and radiating pattern of the three element Yagi antenna which applied the result is well in accord with the theoritical values.

• Proceedings of KHEA Conference
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• 1997.07a
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• pp.123-123
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• 1997

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.29 no.6
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• pp.473-476
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• 2018

Herein, a $2{\times}2$ subarray antenna is designed to implement a VHF band active electronically scanned array. The Yagi-Uda antenna is used as a radiating element. The bandwidth enhancement and miniaturization of the Yagi-Uda antenna are achieved by optimizing the diameter of a driven element and the length of a director. In addition, the grid reflector is utilized to improve the front-to-back ratio(FBR) and to reduce both the wind resistance and overall system weight. The fabricated $2{\times}2$ subarray antenna fully covers the VHF target band($0.98{\sim}1.02f_c$). The measured maximum gain is 10.61 dBi and the FBR is larger than 26 dB.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.20 no.1
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• pp.15-21
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• 2016

In this paper, we considered a design method of a compact quasi-Yagi antenna for portable UHF RFID readers. The antenna consists of a dipole driver and a reflector printed on a dielectric substrate, and it is fed by a microstrip line. In order to reduce the antenna size, the dipole and reflector are bent and the balun between the feeding microstrip line and coplanar strip (CPS) line is integrated within the CPS line. The effects of the geometrical parameters of the proposed antenna on the antenna performance are examined, and the parameters are adjusted to be suitable for the operation in UHF RFID band (902-928 MHz). The size of the fabricated antenna is $70mm{\times}75mm$, and the experiment results reveal a frequency band of 892-942 MHz for a voltage standing wave ratio < 2, a gain > 3.5 dBi, and a front-to-back ratio > 6.6 dB over the frequency band for UHF RFID.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.20 no.12
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• pp.2199-2205
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• 2016

In this paper, a design method for a coplanar waveguide (CPW)-fed 2-element quasi-Yagi antenna (QYA) is studied. A balun between CPW and coplanar strip (CPS) which feeds a planar dipole is implemented by connecting the one end of ground strips in a CPW to a signal strip. The antenna size is reduced by bent strip dipole and reflector, and an integrated balun. The proposed antenna was designed for the operation in a UHF radio frequency identification (RFID) band of 902-928 MHz, and the effects of various parameters such as dipole length, reflector length, distance between dipole and reflector, feed position were examined. The antenna with a size of $90mm{\times}80mm$ was fabricated on an FR4 substrate, and the experiment results reveal a frequency band of 885-942 MHz for a voltage standing wave ratio < 2, a gain > 4.3 dBi, and a front-to-back ratio > 7 dB over the frequency band for the UHF RFID.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.20 no.9
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• pp.862-867
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• 2009

This paper presents a study on a rectenna for rectification of incident low power microwave signals with power densities less than 2 mW/$cm^2$ at 2.45 GHz. The proposed rectenna is designed and implemented by a rectifier with voltage doubler structure and a printed Yagi antenna which suppress re-radiation of the second order harmonic of fundamental frequency. The printed Yagi antenna has a gain of about 5 dB, and the measured conversion efficiencies of the rectenna are from 32 % to 42 % when its incident power levels are from 0 dBm to 14 dBm. The developed rectenna is expected to be useful in the power transmission system.

• Journal of electromagnetic engineering and science
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• v.13 no.3
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• pp.178-185
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• 2013

This paper introduces a high-efficiency, high-gain, broadband quasi-Yagi antenna, and its four-element array for use in 60-GHz wireless communications. The antenna was fed by a microstrip-to-slotline transition consisting of a curved microstripline and a circular slot to allow broadband characteristics. A corrugated ground plane was employed as a reflector to improve the gains in the low-frequency region of the operation bandwidth, and consequently, to reduce variation. The single antenna yielded an impedance bandwidth of 49 to 69 GHz for $|S_{11}|$ <-10dB and a gain of >12.0 dBi while the array exhibited a bandwidth of 52 to 68 GHz and a gain greater than 15.0 dBi. Both proposed designs had small gain variations (${\pm}0.5$ dBi) and high radiation efficiency (>95%) in the 60-GHz bands. The features of the proposed antenna were validated by designing, fabricating, and testing a scaled-up configuration of the single antenna at the 15-GHz band. The measurements resulted in an impedance bandwidth of 13.0 to 17.5 GHz for $|S_{11}|$ <-10dB, a gain of 10.1 to 13.2 dBi, and radiation efficiency in excess of 88% within this bandwidth. Additionally, the 15-GHz antenna yielded quite symmetric radiation profiles in both E- and H-planes, with a high front-to-back ratio.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.19 no.12
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• pp.1360-1366
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• 2008

This paper proposes a printed yagi-antenna available at 2.45 GHz, for the remote-management system of the underground equipment. To improve the solidity and waterproof property, the proposed antenna is coated with bakelite. The manufactured antenna is operated at $2.15{\sim}2.52\;GHz$, whose gain measures 10 dBi. These results are a little different from those of the simulated antenna, but the trend is totally similar. Developed antenna is expected to be useful in the underground facility.