• Journal of The Institute of Information and Telecommunication Facilities Engineering
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• v.7 no.1
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• pp.41-58
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• 2007

A compact and broadband $4{\times}1$ array antenna was developed for 3G smart antenna system testbed. The $4{\times}1$ uniform linear array antenna was designed to operate at 1.885 to 2.2GHz with a total bandwidth of 315MHz. The array elements were based on the novel broadband L-probe fed inverted hybrid E-H (LIEH) shaped microstrip patch, which offers 22% size reduction to the conventional rectangular microstrip patch antenna. For steering the antenna beam, a commercial variable attenuator (KAT1D04SA002), a variable phase shifter (KPH350SC00) with four units each, and the corporate 4-ways Wilkinson power divider which was fabricated in-house were integrated to form the beamforming feed network. The developed antenna has an impedance bandwidth of 17.32% ($VSWR{\leq}1.5$), 21.78% ($VSWR{\leq}2$) with respect to center frequency 2.02GHz and with an achievable gain of 11.9dBi. The design antenna offer a broadband, compact and mobile solution for a 3G smart antenna testbed to fully characterized the IMT-2000 radio specifications and system performances.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.19 no.12
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• pp.1416-1426
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• 2008

In this paper, we present a small size and multiband directional dipole antenna for mobile communication repeaters. In the omni-directional dipole antenna, a planar reflector under the dipole provides improved directivity in front-direction with wide beamwidth. In order to miniaturize the directive dipole, the size of the reflector is reduced. A vertical stub on the reflector is proposed to enhance the front-directivity of the radiation pattern and mitigate the backward radiation due to the reduced reflector. Furthermore, we use horizontal stubs on edge of vertical stub to obtain additional reduction of the antenna size. To meet the current demand of wireless communication service, the designed antenna shows wideband characteristic by employing electromagnetic coupled two-dipoles with dual-resonance frequencies.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.61 no.8
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• pp.1159-1163
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• 2012

In this paper, a new method is suggested to reduce the size of a wide-band array antenna. The power-divider for the feeding structure is made compact as ${\lambda}/8$ with the help of a novel Metamaterial UWB bandpass filter. This power divider is clearly different from others in that the proposed design uses microstrip structured Composite Right and Left-Handed (CRLH) filters, while others use two dielectric layers or long tapered transmission lines. In order to validate the proposed design method, the circuit and full-wave simulated results of the power divider with the Metamaterial UWB filters are compared to each other, and the Metamaterial properties of the structure are shown with the electric field at the ZOR and dispersion diagram. Furthermore, the antenna performance of the fabricated antenna with the power divider is measured and compared with the prediction. Also, the size reduction effect by the proposed scheme is addressed.

• Journal of electromagnetic engineering and science
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• v.14 no.3
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• pp.317-319
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• 2014

In this letter, a small-loop antenna for a mobile UHF RFID device is proposed. To achieve size reduction, a ferrite sheet optimized for a 900 MHz band is applied. The overall dimensions of the antenna are $46mm{\times}35mm{\times}0.24mm$, and it has a bandwidth of 45 MHz with a return loss of less than -6 dB. The proposed antenna satisfies near and far field UHF EPC global frequency band communications (902-928 MHz).

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.8 no.5
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• pp.43-49
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• 2008

Motivated by the Communication Broadcasting Convergence service, various technical approaches are being used to develop more efficient antenna models. This paper proposes a compact mobile antenna which is attachable to a cell phone and is applicable for Communication Broadcasting Convergence. In the design of the antennas for mobile handsets, size reduction is a crucial factor. In this paper, the compactness of a loop antenna is realized by bending a folded-dipole. A short planar dipole is transformed to a twice folded dipole and a loop antenna to produce a larger input resistance. The current distribution of the antenna is the same as a loop antenna, and its radiation patterns are omni-directional. We also analyze the performance of the RFID antenna by exploring the current-induced near field radiation patterns using a electro-optic field mapping system.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.18 no.3
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• pp.497-502
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• 2014

In this paper, a design method for a broadband planar dipole antenna for terrestrial digital television (DTV) reception is studied. The dipole is modified to half bow-tie type for size reduction. The balun between feeding microstrip line and coplanar strip (CPS) line is implemented with a rectangular patch inserted along the center of the CPS line. The proposed antenna is the structure of dual resonances, one is due to the dipole and the other is due to the CPS line attached by the balun. The effects of various geometrical parameters on the antenna performance are examined, and the antenna is designed for terrestrial DTV band (470-806 MHz). The prototype antenna is fabricated on an FR4 substrate with a size of $95mm{\times}178mm$, and tested experimentally to verify the results of this study.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.40 no.9
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• pp.384-391
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• 2003

The wideband annular ring slot antenna with concentric radiating structure and low impedance feedline has been presented. This antenna has been analyzed in compensation for FR-4 substrate with relative permittivity 4.3 and thickness 1 mm. As the measured 10 dB impedance bandwidth of the proposed antenna is 127.2%(2.17∼9.76 GHz), its bandwidth is much broader than maximum 82% bandwidth of a conventional annular ring slot antenna. Experimental results from 2 to 10 GHz are shown to be in good agreement with the simulation. And this antenna has a high gain above 4 dBi from 2 GHz to 10 GHz as well as a 24% size reduction and 42% area reduction than a circular slot antenna.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.26 no.6
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• pp.525-532
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• 2015

In this paper, we propose an equivalent model of array antennas that use open-ended waveguides for effective EM simulation. We first investigate an individual element that consists of an open-ended waveguide and square ground plane. The waveguide length, aperture size, and ground size of the individual element are adjusted to give a similar radiation pattern to that of the individual element of the original antenna. We then apply the designed equivalent model to two different types of array antennas, such as a microstrip patch array and a waveguide array antenna. Comparison of the simulation results using the equivalent model with the results obtained with the original antenna reveals a difference in gain of less than 0.2 dB and a difference in half power beam width(HPBW) of less than $1^{\circ}$. The designed equivalent model is then mounted on a simple aircraft, and the simulation results are again compared to results from the original antenna. We find a 60 % reduction in simulation resources and time when compared with the original antenna model.

• Journal of Advanced Navigation Technology
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• v.17 no.6
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• pp.646-651
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• 2013

In this paper, a small inverted-F antenna with adjustable characteristics is proposed with use of lumped elements, capacitor and resistor. Capacitor is inserted between end of the antenna and ground for size reduction and tuning of resonant frequency. On the other hand, $0{\Omega}$ resistor is replaced as the short line connected to ground. The movement of short point due to use of $0{\Omega}$ resistor results in providing variation of input impedance. Therefore optimum characteristics can be obtained only by proper choice of capacitor and short point without redesign of it's geometry. In order to check the validity, the proposed antenna is designed and fabricated for 2.4 GHz frequency band, and then is applied to a product of Zigbee wireless remote controller. As a result, the size of applied antenna is $8.5{\times}4.5mm^2$ and it is observed that the measured bandwidth and antenna gain are 150 MHz and 2 dBi respectively without redesign of the antenna.

• Journal of the Korean institute of surface engineering
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• v.39 no.3
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• pp.142-146
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• 2006

A novel internal-type linear inductive antenna, which we refer to as a double comb-type antenna, was developed for a large-area plasma source with substrate size of $880\;mm{\times}660\;mm$ ($4^{th}$ generation glass size). In this study, effect of plasma confinement by applying multi-polar magnetic field was investigated. High density plasmas of the order of $3.18{\times}10^{11}\;cm^{-3}$ could be obtained with a pressure of 15 mTorr Ar at an inductive power of 5000 W with good plasma stability. This plasma density is higher than that obtained for the conventional double comb-type antenna, possibly due to the plasma confinement, low rf voltage, resulting in high power transfer efficiency. Also, due to the remarkable reduction in the antenna rf voltage and length, a plasma uniformity of less than 3% could be obtained within a substrate area of $880\;mm{\times}660\;mm$ as rf power increased.