• Journal of Electrical Engineering and Technology
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• v.13 no.1
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• pp.400-405
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• 2018

This paper presents a compact ultra-wideband (UWB) flexible monopole antenna design on a paper substrate. The proposed antenna is made of iterations of a circular slot inside an octagonal metallic patch. This fractal-based geometry has been deployed to achieve compactness along with improved bandwidth, measured reflection coefficient -10 dB bandwidth ranging from 2.7 to 15.8 GHz. The overall size of the antenna is $26mm{\times}19mm{\times}0.5mm$, which makes it a compact one. The substrate used is paper and the main features like environment friendly, flexibility, green electronics applications and low cost of fabrication are the key factors for the proposed antenna. The aforementioned UWB prototype is suitable for many wireless communication systems such as WiMAX, WiFi, RFID and WSN applications. Antenna has been tested for the effect of bending by placing it over a curved surface of a very small radius of 10 mm.

• ETRI Journal
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• v.34 no.1
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• pp.1-8
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• 2012

This paper proposes a reconfigurable beam-steering antenna using a bended dipole and a loop. The radiation patterns of the two antennas are cancelled or compensated, and headed towards a specific direction when the dipole and loop antenna are combined at a reasonable ratio. The proposed antenna can steer the beam directions by controlling the operation of two artificial switches. The proposed antenna was manufactured on a PCB (FR-4) and a flexible PCB (polyimide). In the case of the antenna that was fabricated on a PCB, the maximum beam directions were $+50^{\circ}$, $0^{\circ}$, and $-50^{\circ}$ in the azimuth direction using the two artificial switches, and the antenna gain was 1.96 dBi to 2.48 dBi in the operation bandwidth of 2.47 GHz to 2.53 GHz. Also, the antenna was fabricated on a flexible PCB and measured under various bending conditions for wearable applications.

• Journal of Positioning, Navigation, and Timing
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• v.11 no.2
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• pp.91-98
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• 2022

In the next generation wireless communication system, the beamforming technique based on a massive antenna is one of core technologies for transmitting and receiving huge amounts of data, efficiently and accurately. For highly performed and highly reliable beamforming, it is required to accurately estimate the Angle of Arrival (AOA) for the desired signal incident to an antenna. Employing the massive antenna with a large number of elements, although the accuracy of the AOA estimation is enhanced, its computational complexity is dramatically increased so much that real-time communication is difficult. In order to improve this problem, AOA estimation algorithms based on the massive antenna with the low computational complexity have been actively studied. In this paper, we compute and analyze the computational complexity of the cascade AOA estimation algorithm based on the Flexible Massive Concentric Circular Array (FMCCA). In addition, its computational complexity is compared to conventional AOA estimation techniques such as the Multiple Signal Classification (MUSIC) algorithm with the high resolution and the Only Beamspace MUSIC (OBM) algorithm.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.23 no.1
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• pp.21-28
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• 2012

In this paper, we propose a flexible zeroth-order resonant(ZOR) antenna. Its zero phase constant ensures that the antenna performance is independent of substrate deformation. A composite right/left-handed transmission line is designed based on coplanar waveguide technology to realize the zeroth-order resonance phenomenon. The CRLH is an implementation of metamaterial(left handed material) which is composed of shunt inductance and series capacitance. In order to yield additional circuital parameter, chip inductor and gap capacitor is added, respectively. The proposed ZOR antenna provides good performances: reasonable bandwidth(6.5 %) and peak gain(0.69~1.39 dBi). Simulated and measured results show that the antenna's resonant frequencies and radiation patterns are almost unchanged at different curvature diameters of 30, 50, 70 mm, as well as for a flat surface.

• The Journal of the Korea institute of electronic communication sciences
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• v.16 no.6
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• pp.1081-1088
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• 2021

The modern wireless communication system employes the beamforming technique based on a massive array antenna with a number of elements, for supporting the smooth communication services. A reliable beamforming technology requires the Angle-of-Arrival(: AOA) information for the signal incident to the receiving antenna, which is generally estimated by the high-resolution AOA estimation algorithm such as Multiple Signal Classification(: MUSIC). Although the MUSIC algorithm has the excellent estimation performance, it is difficult to estimate AOA in real time for the massive array antenna due to the extremely high computational complexity. In order to enhance this problem, in this paper, we propose the cascade AOA estimation algorithm based on a Flexible Massive Concentric Circular Array(: FMCCA) antenna with the On/Off function for antenna elements. The proposed cascade algorithm consists of the CAPON algorithm using some elements among entire antenna elements and the Beamspace MUSIC algorithm using entire elements. We provide computer simulation results for various scenarios to demonstrate the AOA estimation performance of the proposed approach.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.21 no.10
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• pp.951-959
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• 2011

In this study, an OTM(on-the-move) antenna which is mounted on ground vehicles and is used for mobile communication between vehicle and satellite while moving was addressed. Since LOS(line-of-sight) of antenna should direct satellite consistently while vehicle moving to guarantee high satellite communication quality, active antenna LOS stabilization is a core technology for OTM antenna. Stabilization of a satellite tracking antenna which consists of 2-DOF gimbals, an elevation gimbal over an azimuth gimbal, was considered in this study. In consideration of driving mechanism which consists of gear train and flexible driving shafts, a two-mass-system dynamic model coupled with vehicle motion was presented. An internal PI-control loop + outer PI-control loop structure has been suggested in order to damp the torsional vibration and stabilize control system. The classical pole-placement method was applied to design control gains. In addition, a vehicle motion compensation control beside of the feedback control loop has been suggested to improve LOS stabilization performances. The feasibility of the proposed control design was verified along with some experimental results.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.24 no.1
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• pp.20-26
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• 2013

In this paper, we propose a multi-band monopole antenna with a band-notching U-slot, which is fabricated inside the flexible polymide film substrate. The U-shaped slot located on the patch-shaped monopole antenna provides band-notch at 2.7 GHz, but also helps to improve return loss at adjacent frequency bands. The performance of the antenna attached on an automobile-glass has been simulated and measured. The fabricated antenna provides more than 10 dB return loss for ISM band(2.4~2.483 GHz) and WAVE band(5.85~5.925 GHz), 2.8~5.7 dBi maximum gain, and good radiation patterns.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.20 no.11
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• pp.1194-1200
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• 2009

An internal antenna which has 1 cc volume was implemented on the FPCB(Flexible Printed Circuit Board) for the mobile phone. We increased antenna gain and efficiency by the applying of current direction concept on the antenna pattern for this small antenna. Short antenna length for the GSM band was compensated by the spiral inductor on the FPCB. For broadening bandwidth on GSM band, it's applied 2 spiral inductors. A conductor pattern for the DCS band was positioned perpendicular with the FPCB. Antenna was implemented on FPCB that is dielectric constant 4.4 and thickness 0.05 mm, and FPCB was attached on a carrier dimensioned $L{\times}W{\times}H=30{\times}7{\times}5\;mm$. Measurements showed that max. VSWR 2:1, efficiency 42.49~60.95 % and 47.95~73.21 %, average gain -3.72~-2.15 dBi and -3.19~-1.35 dBi on the GSM and DCS band, respectively. These results are good performances among the small antenna. And the radiation patterns are omnidirectional on the H-plane to both band.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.26 no.5
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• pp.455-462
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• 2015

In this paper, we suggested multiband antenna that can be equipped on a inflatable life-jacket, operating VHF-DSC band(156 MHz), COSPAS-SARSAT band(406 MHz) and GPS band(1,575 MHz) for search and rescue survivors quickly. The GPS band antenna was implemented with a square ring-slot planar antenna, and the COSPAS-SARSAT and VHF-DSC band antenna were implemented meander type dipole antennas. In order to place the antenna on a life-jacket, we installed it on 0.2 mm thickness FR-4 substrate to obtain a flexibility. It appeared that the antenna has -14.6 dB, -30.9 dB, and -18 dB return loss in COSPAS-SARSAT, GPS, and VHF-DSC band, respectively. In addition, its gain has 0.83 dBi, 2.1 dBi in COSPAS-SARSAT and GPS band, respectively.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2018.10a
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• pp.526-528
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• 2018

This paper proposes a small, flexible dipole antenna for wireless power transmission of smart devices in a Wi-Fi environment. The proposed antenna is a mini-dipolar antenna structure with a split ring resonator in the center and is a small dipole antenna with a size of 32mm. The split ring resonator dipole antenna showed a reduction of about 20% compared to the same size of the dipole antenna.