• 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.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.11 no.4
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• pp.627-633
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• 2000

In this paper, new printed-type inverted F antenna is designed and fabricated to gain the ideal radiation pattern of a rocket-borne antenna which is expected to show the omni-directional pattern characteristic in rear direction. The radiation pattern of this antenna is measured in condition that the antenna is mounted on the side of the fin which is located on the tail of a rocket or a missile. Measurement result shows that the improved symmetrical radiation pattern is obtained with respect to the radiation pattern of the existing inverted F antenna. Besides parasite element which can be operated as reflector is attached in front of the antenna with the distance between the antenna and the parasite element $\lambda$/8. The result shows that the ratio of the front to the rear radiation level is improved by 8 dB.

• ETRI Journal
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• v.41 no.6
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• pp.715-730
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• 2019

We propose a switched beam-forming antenna that satisfies not only ultra-wideband characteristics but also beam-forming in the WLAN frequency band using an ultra-wideband antenna and passive parasitic elements applying a broadband optimal reactance load algorithm. We design a power and phase estimation function and an error correction function by re-analyzing and normalizing all the components of the parasitic array using control system engineering. The proposed antenna is compared with an antenna with a pin diode and reactance load value, respectively. The pin diode is located between the passive parasitic elements and ground plane. An antenna beam can be formed in eight directions according to the pin diode ON (reflector)/OFF (director) state. The antenna with a reactance load value achieves a better VSWR and gain than the antenna with a pin diode. We confirm that a beam is formed in eight directions owing to the RF switch operation, and the measured peak gain is 7 dBi at 2.45 GHz and 10 dBi at 5.8 GHz.

• Journal of electromagnetic engineering and science
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• v.17 no.1
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• pp.14-19
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• 2017

In this paper, a planar directional beam-switchable antenna with four orthogonal beam directions is proposed. The proposed antenna is designed with two crossed active elements and two parasitic elements for each direction. The design methodology is described on the basis of the Yagi-Uda method for the active and parasitic elements, respectively. By adjusting the effective electric lengths of the parasitic elements, the roles of a director and a reflector are exchanged with each other. The planar four-way beam-switchable Yagi-Uda antenna is implemented. From the experimental results. The proposed design method is verified for orthogonal radiation beam switching.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.20 no.12
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• pp.1233-1242
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• 2009

In this paper, a Base Station Antenna(BSA) utilizing Artificial Magnetic Conductor(AMC) as reflector instead of common conductive plate to improve radiation characteristics and achieve low-profile is proposed. In the case of the conventional BSA on conductive surface which acts as a reflector, a secondary radiation is caused at the corner of the conductive surface, and it increases the back-lobe of the antenna, resulting in deteriorating the radiation characteristic of the conventional BSA. However, using the AMC, the back-lobe of the BSA can be largely reduced by the surface wave suppression. And the Side-Lobe Level(SLL) is also improved, resulting in preventing the service area overlapped. Furthermore, due to the $0^{\circ}$ reflection phase on AMC, the profile of the BSA can be also reduced.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.26 no.11
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• pp.937-950
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• 2015

Microstrip reflectarray is an antenna which controls its radiation pattern with a number of reflective elements. Conventionally, the reflectarray has been researched to replace curved reflector antennas. In this paper, design theories of reflectarray is briefly introduced, and research trends of high gain and broadband reflectarrays are reviewed. To improve the gain of the reflectarrays, it is required that the reflection phase errors on the reflectarray surface be minimized. For this purpose, sufficiently wide reflection phase range and low phase sensitivity should be realized with the designed element. For bandwidth improvement, the reflection phase of the element should be linear with the frequency variation. In this paper, various researches to improve the reflection phase characteristics of the element for high gain and broadband reflectarrays, such as multi-layer and single-layer multi-resonant structures, are reviewed. Also, dual-reflectarray configuration for compact antenna design is reviewed. Finally, various applications of reflectarrays such as contoured beam, near-field focusing, and RCS reduction are reviewed.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.9 no.2
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• pp.41-50
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• 2010

In this paper, a multi-band antenna with novel structure for mobile communications is designed and fabricated. The proposed antenna has the Multi-band antenna characteristics by two common-grounded slots with different size and angle. In order to reduce size and to enhance the gain of the antenna, a reflector is consisted of chokes on the three sides. It is optimized by using the CST Microwave Studio commercial software based on the FIA(Finite Integration Algorithm) and PBA(Perfect Boundary Approximation), and then the fabricating and measuring is practiced. As a result of measurement, the reflection coefficient is less than -11 dB(VSWR < 1.8) and the gain of antenna is more than 6dBi at 824~894MHz and 1885-2500MHz.

• Journal of information and communication convergence engineering
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• v.18 no.3
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• pp.162-166
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• 2020

The present paper presents an array antenna of a microstrip patch for 5G applications. Four rectangular microstrip patch elements are arranged in parallel and series to form an array antenna. Two insets are made on both sides of each patch element to achieve a wide frequency bandwidth of 23.97-31.60 GHz. To attain a high gain and wider bandwidth, the microstrip patch antenna is fed using series and corporate feeding networks. Further, three director elements on top of the top-most patch elements, and one reflector element at the open end of each patch element, are added. The addition of the Yagi elements improved the overall gain and acquired a higher radiation efficiency throughout the operating frequency bandwidth, with the array antenna achieving a maximum peak gain of 8.7 dB. The proposed antenna is built on a low-loss and low-cost substrate of FR4-eproxy. The proposed antenna design with a simple structure is suitable for Internet of Things and 5G applications.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.2 no.1
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• pp.65-72
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• 2009

For the evaluation of far-field performance by using the near-field probing on the base station dipole array antenna, the effects of mutual coupling depending on the heights between the array antenna with reflector and the probe were analyzed. When the height is varied in the near-field region, S parameters on the input ports of antenna and probe are measured and analyzed to decide the height for the minimum mutual coupling effect and the maximum probing efficiency. This height will be applicable to the near-field probing system design to achieve the precision far-field performance of a base station array antenna system.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 1999.11a
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• pp.151-155
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• 1999

We proposed the beam tilted antenna by aperture coupled microstrip array, found out the values of design parameters by using Ensemble 5.1 of Ansoft Co., and analysed the performance of fabricated antenna. In order to point to the fixed satellite on the nothern hemisphere, 3 dB beamwidth of this antenna is 25$^{\circ}C$ to 65$^{\circ}C$. Operation bandwidth is 2.51GHz to 2.59GHz. The structure of this antenna is composed by 3 types of squared patches; reflector, driver, and director. The maximum antenna gain is 6.2dB at 2.56GHz and elevation angle of 42$^{\circ}C$. Front-to-Back ratio is more than 13dB at the same condition.