• Proceedings of the IEEK Conference
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• summer
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• pp.334-338
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• 2004

In this paper, we suggest a new antenna structure for RFID(Radio Frequency IDentification) reader. Conventional RFID reader uses a loop antenna. The central area of a loop antenna shows a low magnetic field strength especially for the case of a large loop antenna diameter. We propose a parallel-fed multiple loop antenna. Simulation results and measured results show that we can adjust field distribution with the number of turns and diameter of an inner loop antenna to obtain a longer reading distance. Simulation results for the specific case of a proposed antenna structure show that at the center point of a proposed parallel-fed multiple loop antenna, the typical card area averaged magnetic field strength is 2.53A/m, which is higher than the case of a conventional type single loop antenna of 0.44A/m and the case of a series-fed multiple loop antenna of 0.96A/m when we drive with same source signal. We realized the antenna for the case of 13.56MHz RFID reader and the performance of reading distance was much more improved than the case of a conventional antenna.

• Journal of Korea Multimedia Society
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• v.12 no.7
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• pp.971-978
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• 2009

The paper is a phase controlled loop antenna for multi-media devices. We developed a phase control loop pattern arrangement methods for loop antenna in mobile devices like as a cell phone and PCS, WCDMA. In the loop antenna pattern, arrange close adhesive the loop antenna pattern $180^\circ$ cycle in wave length, the radiated electro-magnetic wave from close adhesive loop pattern become to coherent wave than the phase controlled loop antenna has high efficiency and high radiation gain. To acquire a wide band width on phase controlled loop antenna, we arrange a multiple phase controlled loop pattern that has a different length each other. Different length for each other loop pattern cause a different frequency that we can acquire a wide band width for loop antenna from close adhesive phase control. In experiment, we designed a CDMA850 mobile multi-media antenna in 20mm$\times$20mm area thickness 0.4mm, the radiation efficiency is over 60% and radiation gain is over 0dBi.

• Journal of the Korean Institute of Telematics and Electronics
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• v.9 no.2
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• pp.17-23
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• 1972

In this paper, the radiation characteristics of a large circular loop antenna with sinusoidal current distribution is studded in a moving media with a constant velocity much less than the speed of light. The diameter of the circular loop antenna is comparable with or larger than wave length. In studing the radiation characteristics, vector potential for the antenna is derived and relative field pattern is plotted from the vector potentials. Finally the field patterns are compared with those of stationary media. It is found that maximum directivities are shifted to the direction of the velocity of the media, and the field intensities are decreased in that direction and increased in opposite direction by the velocity component paralell to the loop plane. It is also found that the deviations for the pattern are proportional to the velocity of the media, the frequency of the distributed current, the diameter of the loop antenna, and the daviation depends only upon the parallel component of the velocity to the loop plane.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.14 no.3
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• pp.217-225
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• 2003

In this paper, in order to investigate the near field distribution characteristic of the Loop Antenna we simulated and measured the near field of a Loop Antenna using optical electric-field sensor in a large Chamber(8.5 m x 7 m x 7 m). The simulation methods were used MoM for frequency domain and FDTD for time domain. From the analysis results, it can be seen that the simulation and measurement results are very aggregated, and the optical electric-field sensor is a certificate of validity. In frequency domain, in case of the optical sensor with vertical polarization is located above the near vertical line of the Loop Antenna the signal strength level is more 15 ㏈ than with horizontal polarization. But in case of the optical sensor located above horizontal line of the Loop Antenna, signal strength level is not different. And, in the time domain, although input signal is positive, in the case of the optical sensor with vertical polarization is located above horizontal line of the Loop Antenna, it can be seen that the received pulse shape is negative.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.61 no.1
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• pp.1-4
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• 2012

In this paper, the planar type modified folded loop antennas for S-DMB band is proposed. The proposed antenna consisted of opened center of a conventional closed loop and folded terminal of microstrip line to inside loop antenna. The sizes proposed antenna was minimized by folding the terminal of the loop. Also, It was minimized reactance value by increasing capacitances between coupled microstrip line. Therefore the proposed antennas compacted about 20% than a conventional loop antenna and increased efficiency of antenna. The proposed antennas got an omni-directional pattern, the antenna gain was 3.67 [dBi] and the bandwidth was 900 MHz (2.6-3.56 GHz) with VSWR${\leq}$2 from the simulated and the measured results. The frequency utilization coefficient was 29.9 %. These properties could satisfy the S-DMB band.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.12 no.2
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• pp.30-37
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• 2013

An extended loop antenna, to be continued BLA(Branch Loop Antenna) in the previous volume, for the mobile handset is designed in this paper. It's introduced an ELA(Extended Loop Antenna) that is added extended loops to rectangular loop, and verified antenna performances for applying to mobile handset. Extended loops are located upside, left and right side of rectangular loop, and low resonance is obtained by the length of line. Multiple resonances are established by the extended loops, and obtained the desired service bands by the connection points and lengths. By the implementation and measurement for the multiband ELA, it's showed -3.0~-1.46dBi average gains with 50.15~71.41% efficiencies at CDMA/GSM frequency band, and -8.28~-1.7dBi average gains with 14.87~67.68% efficiencies at DCS/USPCS/WCDMA frequency band.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2005.11a
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• pp.245-248
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• 2005

In this paper, small sized half-wavelength circular loop antenna which attached beneath a visor of helmet is designed and fabricated at the resonant frequency of 449MHz. To reduce the size of the antenna, double series-shorted stubs are inserted inside the loop for practical use of a vacant space of loop inside. Also, It is designed for the printed type to install the helmet easily. The size of antenna on helmet is reduced to 87.75%(diameter : 70mm, height :.36mm) compare with general type antenna(diameter : 200mm height 101mm). The return loss, -10dB bandwidth and gain are -13.2dB, 17.6MHz(3.9%), and -1.78dBd. And, radiation pattern is omni-directional pattern at H-plane. Therefore, it can be seen that the half-wavelength circular loop antenna using double series-shorted stubs is proper structure for the miniaturization and the installed antenna of the helmet.

• Journal of Korea Multimedia Society
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• v.12 no.9
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• pp.1288-1296
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• 2009

This paper is for multi-frequency thin film loop antenna used on smart phone, PMP and PDA like as a multi-media devices. We developed a loop pattern folding methods to reduce a thin film antenna dimension using that mutual coupling folding loop occurs the higher frequency resonation. To reduce the thin film size for loop antenna, we fold the loop pattern repeatedly control the coupling coefficient than generate a not only higher mode resonation but also basic resonation from loop pattern. To realization the thin film folded loop antenna, we used a $30mm{\times}9mm$ PI film the thickness is 20um so that we realize the CDMA850, GPS, DCS, PCS, WCDMA antenna simultaneously and it's radiation efficiency is over 50% and gain is 0dBi.

• Proceedings of the Korea Society of Information Technology Applications Conference
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• 2005.11a
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• pp.353-356
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• 2005

A loop RFID tag antenna and a dipole RFID antenna with a T-matching method have been designed. The characteristic of loop and dipole with T-matching antenna structures of RFID tag antennas have been studied. The impedance of different sizes of loop and dipole antenna structures are found. This paper shows parametric research of loop RFID antenna structure and RFID dipole antenna with T-matching method to match the impedance of commercially available RFID chips.

• Journal of information and communication convergence engineering
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• v.8 no.5
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• pp.489-492
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• 2010

This paper proposes the planar-type modified monopole antennas of loop structure. This antenna has an opened center of a conventional closed loop structure with an inside-folded terminal of the loop microstrip line. The size of the proposed antenna was minimized by folding the end of the loop. Also, the reactance value has been minimized by increasing capacitances between the coupled microstrip line. Therefore the proposed antenna has been compacted to about 20% from a conventional loop antenna and has increased its efficiency. The proposed antennas have an omni-directional pattern, the antenna gain was 3.67 [dBi] and the bandwidth was 900 MHz (2.6~3.56 GHz) with VSWR$\leq$2 from the simulated and the measured results. The frequency utilization coefficient was 29.9%. These properties could satisfy the S-DMB band.