• Korean Journal of Optics and Photonics
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• v.20 no.2
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• pp.65-70
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• 2009

In this paper, a THz Yagi-Uda antenna with high input impedance is designed. By placing the antenna on a thin substrate, end-fire radiation patterns with high antenna impedance can be obtained even when the substrate has high relative dielectric constant. The proposed Yagi-Uda antenna has high input resistance of approximately $4,400{\Omega}$ at the resonance frequency which is obtained by using a U-shaped dipole as a driver element. It is expected that the Yagi-Uda antenna on a thin substrate can achieve much higher terahertz output power than the conventional THz antennas.

• 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.

• Korean Journal of Optics and Photonics
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• v.19 no.1
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• pp.9-14
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• 2008

In this paper, a new type of Yagi-Uda antenna that operates in the terahertz frequencies is designed. The proposed Yagi-Uda antenna can obtain high input resistance of approximately $2000{\Omega}$ at the resonance frequency by using a full-wavelength dipole instead of a half-wavelength dipole as the driver element. The current leakage into the bias line was minimized by applying the photonic bandgap structure to the bias line. By designing the antenna on a thin substrate, the impedance lowering of an antenna caused by the relative dielectric constant of the substrate was prevented and the end-fire radiation pattern which is the original radiation characteristic of the Yagi-Uda antenna could be obtained. We expect that the proposed Yagi-Uda antenna can achieve increased terahertz output power by improving the impedance mismatching problem with the photomixer.

• The Journal of the Korea institute of electronic communication sciences
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• v.11 no.11
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• pp.1039-1046
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• 2016

To study a habit and life patten of a wild animal, this paper do a research on the location tracing system of wild animal by yagi-antenna low pass filter, angle tracking technology. Commonly, VHF Radio Telemetry is used for the location tracing system of wild animal. Considering movement, Previous yagi-antenna has 4-element and has advantage of portability but the other advantages are small and preference is weak. To make the advantage of yagi-antenna higher than previous one, Supposed technology adapt to 6-element and make out Narrow space yagi-antenna technology. Also, It supposes that AOA (:Angle of arrival) technology is applied to detecting technology for a close direction from received signal. Based on this study suggest that position tracing technology is so as to figure out a life patten and habit of a wild animal which live in a certain area.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.18 no.11
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• pp.1211-1216
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• 2007

Yagi-Uda UHF RFID(Radio Frequency Identification) tag antennas with long reading range have been designed. According to ISO-18000, EIRP(Effective Isotropic Radiation Power) of reader and reader antenna is limited as 36 dBm. Therefore, the gain of a tag antenna should be high enough to extend the reading range. Yagi-Uda antenna has been applied to a UHF RFID tag antenna, and high gain and long reading range have been achieved. Three different of Yagi-Uda UHF antennas have been optimized to achieve the small size with low back-lobe patterns. The sizes, reading ranges and return loss of Yagi-Uda tag antennas are compared and measured.

• Proceedings of the KIEE Conference
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• 1994.07b
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• pp.1207-1209
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• 1994

An optimization technique applicable to the Yagi-Uda antenna was proposed in this paper. An objective function, which is the gain of the antenna in our case, was computed using method of moments. Design variables for the Yagi-Uda antenna were chosen with lengths, positions and diameters of the antenna elements. For the optimization process, the evolution strategy technique was adopted. The results were compared with existing results and showed better performances.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.20 no.7
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• pp.608-616
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• 2009

This paper presents a broadband CPS-fed Yagi-Uda antenna. The antenna has a feedline structure much simpler than other Yagi-Uda antennas and it provides more design flexibility in arranging the reflector. To improve the impedance matching, a tapered CPS line is inserted between the thick and thin feedlines. The proposed antenna exhibits the bandwidth of $3.9{\sim}5.9$ GHz (|G| < -10 dB) and the gain of $6.5{\sim}8$ dBi within that bandwidth. At the center frequency of 4.9 GHz, the antenna shows the gain of 7.4 dBi, and HPBW of $98^{\circ}$ along the x-z plane and $73^{\circ}$ along the x-y plane.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.18 no.8
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• pp.937-942
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• 2007

A new, systematic, simplified design procedure for quasi-Yagi antennas is presented. The design is based on the simple impedance matching among antenna components: i.e., transition, feed, and antenna. This new antenna design is possible due to the newly developed ultra-wideband transition. As design examples, wideband quasi-Yagi antennas are successfully designed and implemented in Ku- and Ka-bands with frequency bandwidths of 53.2% and 29.1%, and antenna gains of $4{\sim}5 dBi$ and $ 5{\sim}5.6 dBi$, respectively. The design method can be applied to other balanced antennas and their arrays.

• 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.

• Journal of electromagnetic engineering and science
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• v.12 no.4
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• pp.254-259
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• 2012

This paper presents a closely spaced two-element folded-dipole-driven quasi-Yagi array with low mutual coupling between adjacent elements. The antenna utilizes a T-junction power divider as the feeding network, with an input impedance of $50{\Omega}$. A microstrip-stub is added to the ground plane in the middle of the two elements to improve the mutual coupling characteristics. The folded dipole driver is connected to a $50{\Omega}$ microstrip line via a broadband microstrip-to-coplanar stripline transition with a quarter radial stub. A mutual coupling of less than -22 dB is measured between two folded-dipole-driven quasi-Yagi antennas with a center-to-center spacing of 30 mm ($0.55{\lambda}_0$ at 5.5 GHz). The proposed quasi-Yagi array yields a measured bandwidth of 4.75~6.43 GHz for the -10 dB reflection coefficient and a gain of 6.14~7.12 dBi within the bandwidth range.