• Journal of Satellite, Information and Communications
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• v.9 no.3
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• pp.104-108
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• 2014

This paper represents the effect analysis results of surface-Icing on the UHF-band antenna for Space Launch Vehicle. In order to obtain structural model of the surface-icing, Relative Permittivity of ice at $-180^{\circ}C$ was extracted. Using this surface-Icing model, UHF-band antenna simulation and comparative analysis about the antenna parameters such as resonance frequency, reflection loss and radiation pattern were performed for each case of with or without surface-icing. Simulation results show that resonance frequency is shifted out of operation frequency due to the additional ice permittivity. This resonance frequency changes cause severe affect to the antenna performance and its radiation pattern.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.30 no.3
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• pp.209-214
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• 2019

This paper presents the design of a 920 MHz ultra-high frequency(UHF) band radio frequency identification(RFID) conductive fabric tag antenna. The resistance values of four different conductive fabrics are measured, and the conductivities of the fabrics are calculated. The fabric with the best conductivity is selected, and the best conductivity of the fabric is used to simulate the fabric tag antenna design. The fabric UHF RFID tag antenna with a T-Matching structure and name-tag size of $80{\times}40mm$ is simulated and designed. The simulated and measured results are compared, and a laundry test is performed. The reading range of the fabric tag antenna is about 2 m. This fabric tag can be easily applied to an entrance control system as it can be attached to other fabrics and cloths.

• Journal of the Korean Society for information Management
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• v.26 no.3
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• pp.335-353
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• 2009

Since libraries first used RFID systems in the late 1990's, there is growing debate about the advantages and disadvantages of HF and UHF RFID systems. This study tries to explore practical issues in HF and UHF RFID systems especially in the areas of system characteristics and advantages and disadvantages affecting technology implementation to libraries. This study investigates the current status of RFID systems in Korean libraries, and analyzes the best practices of four libraries(two libraries in HF and two libraries in UHF respectively). Also, this study describes functional characteristics of HF and UHF RFID systems, debates on frequencies in ISO/DIS 28560, and the opinions of both manufacturers which provide RFID systems to libraries and librarians who use HF and UHF RFID systems in their libraries.

• 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.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.8 no.6
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• pp.119-125
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• 2008

In this paper, we proposed the modeling of UHF frequency environment in a random mountainous area with line of sight. A transmitting station is defined as wanted transmitter(Wr) and a receiving station is defined as victim receiver(Vr). These set up victim link. A interference transmitter(It) and wanted receiver(Wr) set up interference link. We compared measured data at random mountainous area with data of the result using spectrum engineering advanced monte calo analysis tool(SEAMCAT), interference simulation based on the monte-carlo method. The desired received signal strength(dRSS) of SEAMCAT had the calculated error of 70% from the measured received signal strength because there was a topographical effect. Therefore, the effect of diffraction interference was included to lessen the power of transmitter in the proposed simulation. The cause of received power error are cable loss and errors of a measuring instrument. The proposed simulation modeling in UHF frequency environment expect that is the useful study on interference analysis and reassignment of broadcasting frequency.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.57 no.1
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• pp.56-59
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• 2008

We have designed 4 types(void in insulation paper, protrusion electrode, floating electrode, surface discharge) of partial discharge(PD) defect to simulate typical faults found in oil filled power transformers. Ultra-high frequency(UHF) radiation due to PD was measured using a UHF measuring system and a conventional PD measuring system, simultaneously. Electromagnetic radiation spectra of these defects show UHF radiation up to about 1.5-2 GHz range. The phase resolved partial discharge(PRPD) patterns of UHF radiation from the PD defects were also measured and the pattern reveals distinct feature for each defect types. The UHF measuring could be used to detect PDs in oil filled transformers and analysis of the PRPD pattern should provide useful information on origin of PD signal.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.57 no.5
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• pp.889-895
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• 2008

In this paper a Fractional-N frequency synthesizer is designed for UHF RFID readers. It satisfies the ISO/IEC frequency band($860{\sim}960MHz$) and is also applicable to mobile RFID readers. A VCO is designed to operate at 1.8GHz band such that the LO pulling effect is minimized. The 900MHz differential I/Q LO signals are obtained by dividing the differential signal from an integrated 1.8GHz VCO. It is designed using a $0.18{\mu}m$ RF CMOS process. The measured results show that the designed circuit has a phase noise of -103dBc/Hz at 100KHz offset and consumes 9mA from a 1.8V supply. The channel switching time of $10{\mu}s$ over 5MHz transition have been achieved, and the chip size including PADs is $1.8{\times}0.99mm^2$.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.27 no.11
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• pp.972-977
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• 2016

This paper introduces development process and results of HF & UHF band(13.56 MHz, 920 MHz) tag antennas using a single-side printing method on a PE film. The size of tag antenna is designed in the area of $80mm{\times}50mm$, little bit smaller than a credit card. The UHF tag antenna, $76mm{\times}44mm$, is located at the outside of the card size tag antenna, and the HF tag antenna, $40 mm{\times}42 mm$, is located at the center of the UHF tag antenna. The UHF and HF tag antennas are designed with consideration of coupling effects. The single-side printing method with a jumper structure without using a via is used to make a loop antenna of HF tag antenna. The reading range of UHF tag antenna is about 6m, and the reading of HF tag antenna is about 5 cm. The designed tag antennas have long enough reading ranges for both bands. The tag is applicable to logistics and authentification.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.57 no.11
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• pp.2047-2053
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• 2008

Auto-ID industries and their services have been improved since decades ago, and radio frequency identification (RFID) has been contributing in many applications. Product management can be the foremost example. In our industrial experiences, RFID in ultra high frequency (UHF) band provides much longer interrogation ranges than that of 13.56MHz; many more applications exist thereby. There should be several interesting and useful ideas on UHF RFID; however, those ideas can be limited due to the inevitable environmental circumstances that restrict the interrogation range in shorten value. This paper discusses the propagation interference among different types of readers (e.g, mobile RFID readers in stationary reader zone) in dense-reader environment. In most cases, UHF RFIDs in Korea will be dependent on the UHF mobile RFIDs. In this sense, the UHF mobile users accidently move into the stationary reader's interrogation zone. This is serious problem. In this paper, we analyze propagation loss and propose the effective channel allocation scheme that can contribute developing less-invasive UHF RFID networks. The simulation and practical measurement process using the commercial CAD tools and measurement equipments are presented.

• Journal of the Institute of Electronics and Information Engineers
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• v.52 no.2
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• pp.75-79
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• 2015

In this paper, a dual band antenna with the operating frequency in HF and UHF band was proposed. The antenna structure consists of three spiral turns coil in the bottom side to generate the HF frequency of 13.56 MHz. In the top of the antenna, an inverted-spiral dipole structure is used to create the UHF frequency of 922 MHz. The dual band antenna was optimized to reduce size with $80mm{\times}40mm{\times}0.8mm$ dimension. The antenna presents the omnidirectional characteristic with high gain. To validate the theoretical design, the antenna was simulated using FR-4 substrate and verified the simulation results.