• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.20 no.5
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• pp.480-492
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• 2009

In this paper, we proposed a broadband U-shaped RFID tag antenna with near-isotropic characteristic at UHF band. The proposed tag antenna is composed of the U-shaped half wavelength dipole and a rectangular shaped feed. The rectangular shaped feed that is located inside U-shaped dipole is connected for conjugate impedance matching with the commercial tag chip. A better constant gain deviation characteristic in the operating frequency band is achieved by inserting a rectangular slit in the lower center of the U-shaped antenna body. On the condition of VSWR<2, the tag antenna had the measured bandwidth of 10.36%, from 860.5 to 954.5 MHz, and 9.84%, from 864.5 to 954 MHz, for antenna without slit and with slit, respectively. On the condition of VSWR<5.8, the tag antennas had the measured bandwidth of 15.78%, from 835.5 to 979.5 MHz, and 15.89%, from 837 to 981.5 MHz, for antenna without slit and with slit, respectively. The difference between the maximum and minimum gain deviations of tag antenna without slit in the operating frequency band is 0.53 dB since the maximum and minimum gain deviations are 3.86 dB and 3.33 dB, respectively. Whereas the difference between the maximum and minimum gain deviations of tag antenna with slit in the operating frequency is 0.06 dB since the maximum and minimum gain deviations are 3.60 dB and 3.54 dB, respectively.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.17 no.6 s.109
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• pp.511-518
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• 2006

In this paper, a small RFID tag antenna in UHF band which has bandwidth-enhanced characteristic is proposed. The shape of the proposed antenna is a meander antenna to have size-reduced characteristic, and it consists of two radiators which make dual resonance in adjacent frequency to enhance bandwidth. By adjusting length and location of each radiator, the proposed antenna can make dual resonance at arbitrary location on the Smith chart, which is able to make impedance matching with RFID tag chip in wide frequency range. And it is apparent that the proposed antenna can have bandwidth-enhanced characteristic according to the simulated and measured results.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.19 no.1
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• pp.1-6
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• 2008

A wearable T-matching dipole UHF RFID tag antenna has been designed using conductive electro-thread. The conductivity of the electro-thread has been measured depending on the number of twisted thread. The measured conductivity has been used for simulation to have accurate simulation results. The flexible electro-thread or fabric has been used for fabricating the antenna instead of using copper tape since the electro-thread is more flexible and wearable than copper tape. The return loss and reading range of the fabricated electro-thread UHF RFID tag antennas have been tested. The reading range is approximately 2.4 m.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.19 no.11
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• pp.1265-1271
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• 2008

In this paper, we propose a new antenna design method for RFID tass on metallic surfaces using a low-cost, high-loss substrate such as FR4. The proposed design method highly reduces the substrate loss due to its dielectric loss, and so improves the radiation efficiency of the tag antenna more than double compared with a conventional PIFA(planar inverted-F antenna). The equivalent circuit model of the antenna according to the proposed method was established and its characteristics were analyzed systematically in this paper. The excellency of the proposed design method was verified by the fabrication and measurement of a prototype antenna.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.18 no.4 s.119
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• pp.398-407
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• 2007

In this paper we proposed the tag antenna with a low performance distortion from an attached surface material using the asymmetric dual-arm dipole antenna(ADDA) structure. The tag is designed to exhibit low performance changes when the tag is attached on a target object(the medical litter receptacle, ${\varepsilon}_r=1.7,\;tan\;{\delta}=0.002$). Detail design parameters for the proposed antenna are optimized to maintain a good readable range in free-space as well as on a target object. The size of the optimized antenna is $100\;mm{\times}50\;mm$. The antenna shows the matching bandwidth($S_{11}$< -10 dB) of 3.7 % and the radiation efficiency of 80 % at the operating frequency. Finally we confirmed the readable range of the tag antenna by measurement and it shows about 5.3 m in free space and 5.5 m on the target object.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.23 no.2
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• pp.270-273
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• 2012

A plastic bolt shape UHF RFID tag has been developed for a live tree. The UHF tag is designed and installed into the head part of the bolt, inserted into a tree for management of tree. If the tag antenna is installed near the high dielectric constant material, the impedance of the tag antenna will be changed, and the tag does not work. Therefore, the dielectric constants of wood and plastic bolt are considered for tag antenna design. The input reflection coefficient characteristics and the reading range patterns are measured and compared. This UHF RFID tag can be applied into a live tree, and the status and location of tree can be controlled with the RFID tag. This developed UHF tag can be applied to any applications and objects using a bolt.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.37 no.1C
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• pp.34-37
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• 2012

The paper introduces the an necklace type UHF RFID tag for a live tree having high dielectric constant. When a general UHF RFID tag is used for the metal and the material with high dielectric constant, the electrical characteristics and impedance of antenna have been changed, and the tag is not recognized by an UHF RFID reader. The necklace type UHF RFID tag has been designed with consideration of the high dielectric constant of the tree material. The name tag for a live tree has been designed with the developed tag antenna. The performance of tag has been measured and the reading range is about 4~5m. The developed UHF RFID tag antenna can be applied to any high dielectric material for various industrial applications.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.28 no.9
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• pp.679-684
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• 2017

This paper presents an UHF(Ultra High Frequency) band small cavity structured RFID(Radio Frequency Identification) tag antenna with a long reading range, designed to apply on metal cart or pallet for auto-parts logistics. The size of tag antennas is $140{\times}60{\times}10mm^3$, attached on a exporting metal cart, and it can give the information of inventory and logistics of carts. By collecting the exported carts and increasing the recovery rate of missing carts or pallets, the paid import tax can be refunded when the carts are returned back to the manufacture. The tag antenna was equipped with a cover to prevent damage, and the dielectric constant of the cover is considered for the simulation. The reading range of the tag antenna is 12 m using LP(Linear Polarization), 10 m with CP(Circular Polarization) reader antennas. This 920 MHz UHF RFID cavity tag ensures the long reading distance of the antenna regardless of the material of the object where it is attached.

• Proceedings of the KSR Conference
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• 2005.05a
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• pp.903-908
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• 2005

Existing ATC/ATO/TWC system has a ATC(Automatic Train Control) antenna for receiving the speed code, a ATO(Automatic Train Operation) antenna for obtaining the exact distance to go to platform and TWC(Train and Wayside Communication) antenna for communication between on-board and wayside system. This paper proposes the ATO/TWC antenna with tele-powering module, telegram transmitter/receiver module. This antenna communicates with a passive type tag(wayside Precision Stop Marker) for the information of distance from the stop position and a active type tag for the door command and status in the platform.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.29 no.2
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• pp.93-98
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• 2018

This paper introduces the development of HF(NFC) and UHF band(13.56 MHz, 920 MHz) tag antennas, imbedded in a box. In dual band antennas, the HF band tag can be used to inspect the box using NFC, and the UHF band tag can be used for logistics. The dielectric constant of the box material is measured and used for simulation. The Ntag213 chip manufactured by NXP is used in HF loop antennas, since NFC is possible with Ntag213. For the UHF band, the Higgs-3 chip manufactured by Alien is used. The HF tag antenna is located at the center of the UHF tag antenna, and the location of the HF tag antenna is calculated while considering coupling effects. The designed tag can be used by both the bands for the purposes of logistics and authentication.