• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.18 no.8
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• pp.913-921
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• 2007

In this paper, we propose a novel small antenna for direction finding applications. The proposed antenna employs a skirt type disk to eliminate the radiation null on the broad-side direction in the high frequency range. Additionally, the multi-section matching stub is used for impedance matching in the low frequency range, The size of the proposed antenna is reduced as a half of the 60cm dipole which has a same resonance frequency of 200MHz. The antenna maintains a donut shape radiation pattern with a broad beam width for a wide range of frequency while the 60cm dipole shows radiation nulls on the broad-side direction and the high side-lobe level from 700MHz to 1,300MHz.

• Proceedings of the IEEK Conference
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• 2004.06a
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• pp.135-138
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• 2004

Mobile phone antenna needs a small size and light weight for carrying and handling. In case of receiving a wide band TV signal, it would be difficult to obtain a good impedance matching between the antenna and the circuit due to a large capacitive reactance of antenna. Buffer amplifier was established on the teflon( ${\varepsilon}_r=3.38$, h=20mils) substrate by using GaAs FET( CPY30 ) and Silicon RF Transistor( BFP540 ) produced by Infineon and experimented.

• Journal of electromagnetic engineering and science
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• v.14 no.3
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• pp.299-305
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• 2014

A wideband circularly polarized (CP) antenna with a single feed is proposed for use in global navigation satellite systems. Its primary radiation elements are composed of two orthogonal bowtie dipoles, which are equipped with double-printed vacant-quarter rings to allow direct matching of the antenna to a single $50-{\Omega}$ coaxial line and to produce CP radiation. The crossed bowtie dipole is appropriately incorporated with a planar metallic reflector to produce the desired unidirectional radiation pattern as well as to achieve a wideband characteristic in terms of impedance matching and axial ratio (AR) bandwidths. The designed antenna was fabricated and measured. The prototype antenna with an overall 1.2-GHz frequency size of $0.48{\lambda}_o{\times}0.48{\lambda}_o{\times}0.25{\lambda}_o$ produced a measured ${\mid}S_{11}{\mid}$<-10 dB bandwidth of 1.05-1.79 GHz and a measured 3-dB AR bandwidth of 1.12-1.64 GHz. It also showed right-hand CP radiation with a small gain variation (${\pm}0.3dB$) and high radiation efficiency (>93%) over the operational bandwidth.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.45 no.6
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• pp.52-58
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• 2008

In this paper, electrically small square loop antenna with SRR (Split Ring Resonator) cover structure is built and tested. The proposed antenna has very small size, ka = 0.34 by Chu limit. The experimental result shows that the resonant frequency and impedance bandwidth($VSWR{\leq}2$) are 906MHz and 5.8MHz (901.7 - 907.5MHz), respectively. The proposed antenna is matched and designed by equivalent circuit model. The proposed antenna is fabricated simple structure without additional matching network and printed on a Teflon substrate without ground plane. Therefore, it has advantages of low cost, small size, and light weight and will be applied to wireless communication systems where small antennas are required.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.19 no.5
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• pp.562-571
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• 2008

In this paper, we propose a novel structure of a spiral antenna with a CP characteristic for RFID reader in UHF band. Since the proposed antenna can be built by printing on a FR-4 substrate, it is appropriate for low-cost mass-production. The antenna is designed to operate in UHF band of $860{\sim}960$ MHz. The CP bandwidth is Increased enough to cover an overall UHF RFID band by using a spiral structure for the antenna arm. The matching bandwidth is broadened by using a quarter-wave transformer between the fred and the antenna body. The proposed antenna has advantages of its easy gain and pattern control with a small antenna size. The measured antenna performance shows the matching bandwidth of 13%, the CP bandwidth of 23%, and the gain of 6.5 dBi. This verifies that the proposed antenna is appropriate for RFID antennas in UHF band.

• Journal of the Korea Institute of Military Science and Technology
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• v.23 no.5
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• pp.459-465
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• 2020

In this paper, a compact antenna assembly for an amplitude comparison direction-finding(DF) method for a small flight vehicle is presented. Designed antenna assembly consists of four antennas and it is mounted on a radius of 1.45 λ_c where λ_c corresponds to the wavelength of the center frequency. To achieve compactness and robustness of the assembly, the elements are fed by end-launch feeding method and have modified aperture shapes of E- or H-sectoral horns. The feeding part consists of SMA connector, stepped impedance matching structure, and square waveguide of 0.6 λ_c × 0.6 λ_c. To achieve different main beam directions for every antenna which is required condition for amplitude comparison DF method, all apertures of the antennas are inclined and it makes the main beam direction of each antenna to top, bottom, left, and right with respect to the axis of the platform. To verify the validation of DF performance of the presented antenna assembly, amplitude comparison curves using measurement results are presented. The bandwidth of the antennas are above 3.2 % in Ku-band(VSWR ≤ 2:1).

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2015.10a
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• pp.65-67
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• 2015

In this paper, small WLAN antenna was designed and investigated. Proposed antenna was configured for microstrip patch antenna ($29mm{\times}29mm$) that was mounted on RF4 dielectric substrate (relative permittivity 4.4, thick 1.6mm, tangent loss 0.025) with $45mm{\times}45mm$. In order to obtain a wide band characteristic, the cutting process was 3.2mm diagonal corners of the patch antenna located on the top of the substrate. Antenna feeding position for 50 ohm impedance matching was decided to be 5.1mm at the central axis in the horizontal direction. As a result, frequency bandwidth satisfying the condition of VSWR<2dB was 2.365-2.45GHz (85MHz, 3.53%) for considering WLAN.

• Proceedings of the IEEK Conference
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• 2004.06a
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• pp.197-200
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• 2004

In this paper, a novel triple-band planar inverted F antenna(PIFA) is proposed. The goal of this paper is to design a small antenna which is operated in triple band. Using T-shape slit and stacked U-shape parasitic patch, good impedance matching is achieved in three band. T-shape slit is inserted on the main patch in order to effectively control the excited patch surface current distributions. The proposed antenna occupies a small volume of $26{\times}9.5{\times}6mm^3$, and the obtained impedance bandwidths cover the required operating bandwidths of the GPS(1565-1585MHz), IMT-2000(1885-2200MHz) and Bluetooth (2400-2484MHz) bands.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.18 no.5
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• pp.1022-1027
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• 2014

Based on the modeling of DGPS antenna and antenna site environment, the DGPS short-monopole antenna performance according to the antenna surrounding environment are analyzed in this paper. The DGPS antenna site modeling that considers the ground conductivity and radio wave obstacles is performed and the general requirements for DGPS antenna site are proposed. In case of antenna site with proper radials on the ground plane of the fixed scale, the effect for antenna matching network due to the ground conductivity and radio wave obstacles is small but the impact on the radiation efficiency is large. To provide the stable DGPS service, it is important to install the DGPS antenna on the flat ground plain with good conductivity and without radio wave obstacles.

• ETRI Journal
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• v.33 no.5
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• pp.802-805
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• 2011

This letter presents a K-band polarization reconfigurable antenna integrated with a silicon radio frequency MEMS switch into the form of a compact package. The proposed antenna can change its state from linear polarization (LP) to circular polarization (CP) by actuating the MEMS switch, which controls the configuration of the coupling ring slot. Low-loss quartz is used for a radiating patch substrate and at the same time for a packaging lid by stacking it onto the MEMS substrate, which can increase the system integrity. The fabricated antenna shows broadband impedance matching and exhibits high axial ratios better than 15 dB in the LP and small axial ratios in the CP, with a minimum value of 0.002 dB at 20.8 GHz in the K-band.