• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.21 no.1
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• pp.90-97
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• 2010

In this paper, we propose antenna topology and ground plane shape to improve the performance of PIFA (Planar Inverted F Antenna) which is built-in mobile phone. First, we designed the PIFA antenna consists of multiple radiators to provide multi-current paths. Then we designed U-shaped ground plane on the PCB under the antenna. The proposed antenna structure shows TRP/TIS improvement of 2.0 dB/3.7 dB for GSM and 2.2 dB/ 2.0 dB for DCS and 0.8 dB/1.5 dB for PCS and 1.3 dB/0.7 dB for WCDMA at the free space.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.47 no.7
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• pp.51-58
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• 2010

Wireless Mesh Network has drawn much attention due to wide area service coverage with low system cost. However, there is a bottleneck problem in wireless mesh network since the traffic is aggregated into a gateway. Placement of multi-radio can easy the bottleneck problem, but without careful design it results in unnecessary system cost increasement. In this paper, we propose a system cost minimization through differential antenna placement where optimum antenna placement is determined by the required wireless link capacity. With CPLEX program, optimum number of antennae is determined as a function of local user traffic and gateway capacity. From numerical analysis, it is confirmed that our proposed model can solve bottleneck problem, and at the same time save the system cost.

• Journal of the Korean Vacuum Society
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• v.18 no.3
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• pp.176-185
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• 2009

The realization and the performance of ICP source are strongly affected by its electrical impedance and the electric/magnetic field distribution. The ICP source impedance is determined by the antenna impedance and the plasma one. It is preferred to keep the imaginary impedance between -100 ohm to 100 ohm, since it should be avoided the high voltage formation on the antenna and abrupt impedance variation during the thin film process. The plasma uniformity is affected by the electric and magnetic field which is formed by the antenna current and voltage. The influence of azimuthal symmetry are shown by the electromagnetic simulation and the measurement result of plasma density. The radial uniformity can be controlled by locating the concentric antennas which have different diameters. The power distribution ratio and its control method are presented in the case of parallel antenna connections.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.48 no.2
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• pp.79-84
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• 2011

In this paper we design MIMO antenna with high isolation between antennas by using an isolation aid for WLAN. Two dual-band PIFAs which operates IEEE 802.11n are arranged symmetrically along the central axis of antenna frame and ground plane. By inserting an isolation aid between two PIFAs the isolation is improved maximum 5dB and 7dB for 2.4GHz band and 5GHz band respectively. Total efficiency is above 60%. ECC is below 0.1.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.19 no.6
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• pp.603-611
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• 2008

In this paper, we introduce a multi-coil antenna which is useful for reducing the effects of radio frequency noise in an inductively coupled RFID system. A multi-coil antenna is composed of a central coil and four subsidiary coils that are connected in series. A multi-coil antenna is designed so that the total noise disappear when the induced voltages of a central coil and subsidiary coils are added. The noise in a multi-coil antenna was about 30 dB lower than that in a single coil antenna. The multi-coil antenna is very effective in noise reduction even in an environment that the spatial distribution of RF noise is changed abruptly, and the induced noise was about 16 dB lower than that in a dual coil antenna.

• Journal of Advanced Navigation Technology
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• v.4 no.2
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• pp.152-161
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• 2000

Recently, it is considered to combine the GPS receiver with the GLONASS for the improvement of performance and accuracy. This combined system reduces errors by SA for GPS, and has merits to select receivable satellite. In this paper, aperture-coupled patch antenna and small sized ceramic dielectric patch antenna are designed and implemented for GPS/GLONASS combined receiver, which show a wideband characteristics with circular polarization. The manufactured antennas have the bandwidth more than 240 MHz, VSWR less than 1.5:1, and the axial ratio less than 3dB, and satisfy required characteristics of the GPS/GLONASS antenna.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.26 no.5
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• pp.483-491
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• 2015

This paper describes the design optimization of parasitic elements used for TACAN broadband antenna. We deployed parasitic elements arranged in a circular array to electronically rotate the antenna instead of employing a mechanically rotated antenna to generate the composite radiation pattern of 15 Hz and 135 Hz including bearing information and to meet the harmonic contents specification of MIL-STD-291C. We performed the simulation for optimization of the parasitic elements and fabricated the antenna composed of 16 parasitic elements of 15 Hz and 63 parasitic elements of 135 Hz. With harmonics magnitude reduction by increasing the number of steps using vector composition of the reflectors, the measured result meets the specification of MIL-STD-291C.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.26 no.1
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• pp.54-62
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• 2015

This paper describes the design and fabrication of an electronically rotated Tactical Air Navigation(TACAN) antenna using parasitic elements and PIN diode switches. We used parasitic elements arranged in a circular array and PIN diode switches to electronically rotate the antenna instead of employing a mechanically rotated antenna using motor. The antenna's physical characteristics and design features to generate the cardioid pattern and nine-lobe pattern including bearing information are described and simulated. The measured result shows a very good agreement with simulation and meets the specification of MIL-STD-291C.

• Aerospace Engineering and Technology
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• v.9 no.1
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• pp.106-115
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• 2010

Because of space limitations, interferences between antennas of the KSLV-I communication systems occur and their effects become worse during all sorts of tests such as the flight test using a light plane. In this paper, coupled signal magnitude is calculated using the FDTD method. The theory of the FDTD, absorbing boundary condition, source input technique, and post processing of data are explained. The calculated coupling factor between two IFAs, which have 2 GHz resonance frequency and placed 5 cm apart, is -12.7 dB. Applied coupling calculation method can be effectively used for KSLV-I performance analysis, subsystem design, antenna arrangement, and communication link budget for the next space launch vehicle.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.23 no.1
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• pp.131-137
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• 2023

In this paper, a phase comparison direction finding method of circular array composed of 8 antennas considering polarization characteristics is analyzed. A broadband cavity-backed patch antenna operating in 6 ~ 12 GHz is used, and the antennas are arranged in radial direction to receive various polarization signals. For the phase comparison, widely spaced elements are used to obtain precise DOA(Direction of Arrival), and narrowly spaced elements are used to resolve ambiguity. Two dimensional direction finding is performed for ±20° in both azimuth and elevation, and the DOA error is less than 0.5° and 1.6° near the boresight and the ±15° region, respectively.