• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.5
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• pp.2325-2331
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• 2012

Planar square-spiral antenna using a strip conductor is proposed and analyzed for RFID system in UHF band operating from 860MHz to 960MHz. By varying the length of common line, detached distance, strip line-space, strip line-width and the number of spiral turn, the optimized antenna are designed and fabricated in compact size without a matching-stub between the input port of the proposed antenna and RFID tag chip. From the optimized results, the frequency bandwidth in VSWR<2 has covered 100MHz in the RFID UHF band. The antenna gain has obtained 3.5dBi at the center frequency of 910MHz and the desired beam pattern has shown directional pattern on elevation and azimuth angle. Therefore, the proposed antenna is suitable for practical RFID applications requiring various tag chips with the specific input impedance.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.20 no.9
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• pp.823-828
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• 2009

A small UHF RFID tag antenna for a key-chain installed inside of a metallic key-management cabinet has been designed. The tag antenna has been designed as small size as $66\;mm{\times}6\;mm$ with consideration of coupling among the tag antennas and metallic parts of key-chain and cabinet. The tag antenna is fabricated with a meander line dipole using T-matching method with FR-4 substrate. One tag antenna has been designed with consideration of coupling of adjacent tag antennas, and the other has been designed for the location close to the metallic part in the cabinet. The characteristics of tag antennas and reading distance have been analyzed based on the different numbers of adjacent tag antennas. As a results, the 360 tag antennas installed in the cabinet have been successfully recognized.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.17 no.12 s.115
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• pp.1240-1248
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• 2006

This paper presents an UHF band(911 MHz) RFID tag antenna which has near-isotropic radiation pattern and easy conjugate impedance matching characteristics to any commercial chips of usual practice through the application of an inductively-coupled feeding. The proposed antenna of compact size $40{\times}46mm\;(0.12{\times}0.14{\lambda})$ has, at normal incidence, the maximum RCS of $-18.5dBm^2$ and the 3 dB RCS bandwidth of 9 MHz(1 %) in case of short chip load. It has the maximum and minimum RCS' of $-16.9dBm^2\;and\;-21.4dBm^2$ depending on the incident angles. The difference of about 4.5 dB is relatively small compared with that (about 70 dB) of a pure dipole antenna. The designed antenna has been fabricated and its RCS' have been measured varying the angles of incidence. The measured RCS' have been found to have good agreement with the simulated ones.

• KIEE International Transactions on Electrophysics and Applications
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• v.3C no.5
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• pp.177-181
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• 2003

Partial discharge pulse shapes from variable PD (partial discharge) sources sustain many characteristics such as types of PD. Ultra high frequency antennas have wide bandwidth from 30KHz to 2㎓. Therefore, signals taken from a UHF antenna have important attributes (rising time, falling time, shape factor, etc.) for electromagnetic sources, such as PD sources. We investigated PD pulse shapes from several PD sources using a UHF antenna and the results were used for classification of PD sources. Features for discrimination are extracted from frequency distribution and LPC (Linear Prediction Coefficient) of time signal. RBFN are used for investigating the possibility of classification of multi-PD sources.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.16 no.9 s.100
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• pp.872-882
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• 2005

In this paper, we examined the operating principle of a passive tag antenna for RFID system in UHF band. Based on the study, we proposed a novel RFID tag antenna which adopts the inductively coupled feeding structure to match antenna impedance to a capacitively loaded commercial tag chip. The proposed tag antenna consists of microstrip lines on a thin PET substrate for low-cost fabrication. The detail structure of the tag antenna were optimized using a full electromagnetic wave simulator of IE3D in conjunction with a Pareto genetic algorithm and the size of the tag antenna can be reduced up to kr=0.27($2 cm^2$). We built some sample antennas and measured the antenna characteristics such as a return loss, an efficiency, and radiation patterns. The readable range of the tag antenna with a commercial RFID system showed about 1 to 3 m.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2015.10a
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• pp.73-74
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• 2015

In this paper, a digital terrestrial TV reception antenna which can be applied to the fade zone was designed and investigated. The proposed antenna was configured for a wire antenna structure with $16cm{\times}14cm$, and the antenna parameters are calculated by using the MoM method. The proposed antenna can be used to the receiver for domestic digital broadcast in UHF.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2016.05a
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• pp.87-88
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• 2016

In this paper, a digital terrestrial TV reception antenna which can be applied to the house and vehicle windows was designed and investigated. The proposed antenna was configured for a monopole antenna structure with $230mm{\times}430mm{\times}3mm$, and the antenna parameters are calculated by using the OpenFDTD simulator. The proposed antenna can be used to the receiver for domestic digital broadcast in UHF.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.20 no.10
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• pp.1084-1090
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• 2009

This paper presents a balun consisting of a T-junction, a Right/Left Handed Transmission line(RLH-TL), and a conventional Right Handed(RH) line. It is assumed that the RLH-TL consists of N unit-cells. We provide closed-form solutions and design a very compact wideband(80 %) balun using CPW lines based on the obtained solutions. Then, we propose a capacitively loaded loop antenna designed for a uniform current distribution. The antenna resistance of the proposed antenna at resonance is about 204 ohms. The length of the unit cell is about $\lambda/12$(total length: $1\;\lambda$). The magnetic field generated from the proposed antenna is stronger than that of the conventional one by as much as 20 dB. We used a coplanar strip line(CPS) to combine the loop antenna and balun. The proposed antenna may be used as a near field UHF RFID reader antenna.

• The Journal of the Korea institute of electronic communication sciences
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• v.5 no.2
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• pp.119-124
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• 2010

In this paper, microstrip antenna for Digital TV from 406 to 806 MHz has been designed and fabricated. In order to broaden the bandwidth of the antenna and improve of frequency properties, slot size, radius for capacitance controls were changed. DTV antenna was designed using HFSS simulation program and fabricated by FR4 substrate of dielectric constant 4.4.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.20 no.10
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• pp.1114-1120
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• 2009

The conductivity of various electro-threads is analyzed, and the washable electro-thread embroidery UHF RFID tag antennas using the character shape without T-matching structure are designed by adding a T-matching structure. The RFID tag antenna using the electro-thread is easy to be embedded on a cloth as a wearable antenna because it is flexible and different from general copper inlay shape and tape type tag. The embroidery tag antennas are designed with the English alphabet 'F' and the Korea alphabet 'ㄹ' character. Those are easy to be applied to general clothes. The parameters of antennas are optimized and fabricated. The characteristics and the reading range patterns of the tag antennas are measured. The reading ranges of wet tags(tap water, sea water and soapy water) are tested and compared.