• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2010.05a
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• pp.662-664
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• 2010

In this paper, it is studied that the design method for the planar quasi-Yagi antenna suitable for the operation over 5-10GHz band. Yagi antenna is fed by a short-ended microstrip line and matched by a Balun circuit embedded within the antenna. The results for the characteristics of the Yagi antenna fabricated on the FR4 substrate (${\epsilon}_r$= 4.4, h=0.8mm) agreed well with those predicted by computer simulations.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.19 no.2
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• pp.207-213
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• 2008

A simplified design procedure for quasi-Yagi antenna arrays using an ultra-wideband balun is presented. The proposed antenna design procedure is based on the simple impedance matching among antenna components: i.e., balun, feed, and antenna This new broadband and high gain antenna array is possible due to the ultra-wideband performance of the balun. As design examples, wideband $1\times4$ and $1\times8$ quasi-Yagi antenna arrays are successfully designed and implemented in Ku-band with frequency bandwidths of about 50 % and antenna gains of 9$\sim$10 dBi and 11$\sim$12 dBi, respectively. And the simulated and measured results demonstrate wide bandwidths and good radiation properties. These antenna arrays can be applied to various phased-array and spatial power combining systems.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2012.05a
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• pp.70-73
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• 2012

In this paper, we introduce a design method for a quasi-Yagi antenna (QYA) with broadband characteristics of an impedance bandwidth ratio of > 2 : 1 and a gain of > 4 dBi. The QYA is fed by a microstrip line fabricated on a coplanar strip line and it consists of 3 elements; a planar dipole, a nearby director close to the dipole, and a ground plane reflector. By placing a rectangular patch-type director with large width near to the dipole driver, broadband characteristics are achieved. An optimized 3-element QYA for operation over 1.6-3.5 GHz (bandwidth ratio 2.2 : 1) is fabricated on an FR4 substrate with a size of $90mm{\times}90mm$ and tested experimentally. The results show an impedance bandwidth of 1.56-3.74 GHz (bandwidth ratio 2.4 : 1) for VSWR < 2, a peak gain of 4.41-6.53 dBi, and a front-to-back ratio (FBR) > 13.6 dB within the bandwidth.

• Journal of Advanced Navigation Technology
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• v.16 no.5
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• pp.760-765
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• 2012

In this paper, we studied a design method for a quasi-Yagi antenna (QYA) with broadband characteristics of an impedance bandwidth ratio greater than 2 : 1 and a gain > 4 dBi. The QYA is fed by a microstrip line fabricated on a coplanar strip line and it consists of 3 elements; a planar dipole, a nearby director close to the dipole, and a ground plane reflector. By placing a wide rectangular patch-type director near to the dipole driver, broadband characteristics are achieved. An optimized 3-element QYA for operation over 1.6-3.5 GHz (bandwidth ratio 2.2 : 1) is fabricated on an FR4 substrate with a size of 90 mm by 90 mm and tested experimentally. The results show an impedance bandwidth of 1.56-3.74 GHz (bandwidth ratio 2.4 : 1) for VSWR < 2, a peak gain of 4.2-6.3 dBi, and a front-to-back ratio (FBR) > 13.6 dB within the bandwidth.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2012.10a
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• pp.583-585
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• 2012

In this paper, we introduce a design method for a broadband planar quasi-Yagi antenna (QYA) for terrestrial digital television (DTV) receiving. The coplanar strip line feeding the driver dipole is connected to a microstrip line and is terminated by short circuit. By appending a wide strip-type director at a location close to the driver dipole, a broadband impedance matching and a gain characteristics 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 bowtie (V)-shaped elements. The effects of various parameters on the antenna characteristics are examined. An antenna, as an 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 tested experimentally to verify the results of this study.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2015.10a
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• pp.939-940
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• 2015

In this paper, a design method for a quasi-Yagi antenna (QYA) suitable for UHF band is studied. Due to the mutual coupling between a coplanar strip (CPS)-fed planar dipole and a conducting strip director placed close to the dipole, the dipole obtains broadband characteristics. A ground reflector improves gain in the lower frequency band, and the antenna size might be reduced by employing a bent reflector. The balun between the CPS line and the microstrip(MS) line is constructed by connecting the end of MS line and the CPS line through a shorting pin. In addition, a ring-type conductor connects the CPS line and reflector. The effects of various geometrical parameters and balun on the antenna characteristics are examined. An antenna, as an design example for the proposed antenna, is designed for the operation in the frequency band of 470-806 MHz for terrestrial DTV.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2015.05a
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• pp.475-476
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• 2015

In this paper, we introduce a novel feeding method for a broadband planar quasi-Yagi antenna (QYA) for terrestrial digital television (DTV) receiving. The balun between the balanced coplanar strip (CPS) line feeding the driver dipole and the unblanaced microstrip line is a rectangular patch inserted into the CPS line along the center of the CPS. The end of the balun is connected to the CPS line through a shorting pin. The effects of various geometrical parameters and balun on the antenna characteristics are examined. An antenna, as an design example for the proposed antenna, is designed for the operation in the frequency band of 470-806 MHz for terrestrial DTV.

• 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.

• 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 %.