• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.9
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• pp.4165-4170
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• 2012

In this paper, a method for the improvement in the gain and bandwidth of a microstrip-fed broadband planar quasi-Yagi antenna (QYA) is studied. The broadband characteristics of the QYA are achieved from the coplanar strip-fed planar dipole driver and a parasitic director close to the driver. In order to obtain stable gain variation over the required frequency band, a director and a ground reflector are appended to the driver having a nearby parasitic director. The QYA is fed through an integrated balun composed of a microstrip line and a slot line which are terminated in a short circuit. By adjusting the feeding point, a broadband impedance matching is obtained. A QYA with an operating frequency band of 1.75-2.7 GHz and a gain > 4.5 dBi is designed and fabricated on an FR4 substrate with dielectric constant of 4.4 and thickness of 1.6mm. The experimental results show that the fabricated antenna has good performance such as a broad bandwidth of 59.7%(1.55-2.87 GHz), a stable gain between 4.7-6.5 dBi, and a front-to-back ratio > 10 dB. The measured data agree well with the simulation, which validates this study.

• 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.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.39 no.5
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• pp.251-258
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• 2002

In this paper, the dipole-fed planar array antenna applied Yagi-Uda antenna away theory to microstrip antenna is designed and fabricated at X-band. The design procedure of the dipole-fed planar array antenna with the wide bandwidth is presented to be easily practiced to a wireless communication system. The radiation pattern, return loss and bandwidth of the antenna are improved by the finite differential time domain(FDTD) numerical method. The propriety of analysis of planar dipole antenna is proved from the measured data. From the measured results, the antenna maximum gain is 4.9dBi at center frequency of 10GHz and frequency bandwidth is about 40%. Front-to-back ratio is 16dB, and half-power beam-width of E-plane and H-plane are 117$^{\circ}$and 156$^{\circ}$, respectively. When VSWR of antenna is less than 2, the measured results are agreed well with the theoretical values in the frequency range from 7.4GHz to 11.88GHz.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.24 no.1
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• pp.27-35
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• 2013

In this paper, a compact, broadband quasi-Yagi antenna utilizing balance analysis of the ultra-wideband microstrip-to-coplanar stripline(MS-to-CPS) balun is proposed. The antenna size was reduced by removing the reflector on bottom layer and ground plane is used as a reflector. A planar balun that transforms from microstrip(MS) to balanced coplanar stripline(CPS) is characterized in the amplitude and phase imbalances at CPS output ports are investigated and discussed. As compared with the conventional balun, the proposed MS-to-CPS balun demonstrated very wideband performance from 7 to over 20 GHz. From the simulation study, amplitude and phase imbalances are within 1 dB and ${\pm}5^{\circ}$, respectively. The implemented antenna provides very wide bandwidth from 6.9 to 15.1 GHz(74.5 %). The gain of the antenna is from 3.7 to 5.5 dBi, the front-to-back ratio is more than 10 dB, and the nominal radiation efficiency is about 94 %.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.4
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• pp.1908-1914
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• 2013

In this paper, we introduce a design method for a broadband planar quasi-Yagi antenna (QYA) for terrestrial digital television (DTV) reception. The coplanar strip line which feeds the driver dipole is connected to a microstrip line and is terminated by short circuit. By appending a wide strip-type rectangular director at a location close to the driver dipole, broadband impedance matching and gain enhancement in a high frequency region are obtained. The gain characteristics in a low frequency region are improved by adding a reflector formed by a truncated ground plane. To reduce the antenna size, the strip-type dipole and reflector are modified to half bow-tie (V)-shaped elements. The effects of various parameters on the antenna characteristics are examined. An antenna, as a design example for the proposed antenna, is designed for the operation in the frequency band of 470-806 MHz for terrestrial DTV. The optimized antenna is fabricated on an FR4 substrate and the experimental results show that the antenna has a good performance such as a frequency band of 450-848 MHz for a VSWR < 2, gain > 4.1 dBi, and front-to-back ratio > 10.4 dB.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• v.9 no.2
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• pp.1091-1094
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• 2005

This paper presents analysis and design for printed directive antenna using Bluetooth AP system. For the miniaturization of the antennas, dielectric substrate (${\varepsilon}_r$=4.6) and planar line Yagi-Uda antenna structure are used. The proposed Yagj-Uda antennas are simulated using commercial simulator (HFSS). The results of the simulation are presented and compared with characteristics of each array type. Especially, the proposed antennas can be applied to the design of various communication systems for 2.4 GHz band.