• Journal of Communications and Networks
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• v.13 no.3
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• pp.250-256
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• 2011

A two-way relaying (TWR) system is analyzed, where two source terminals with unequal numbers of antennas exchange data via an amplify-and-forward relay terminal with a single antenna. In the system considered herein, the link quality between the sources and relay can generally be asymmetric due to the nonidentical antenna configuration, power allocation, and relay location. In such a general setup, accurate bounds on the average sum rate (ASR) are derived when beamforming or orthogonal space time block coding is employed at the sources. We show that the proposed bounds are almost indistinguishable from the exact ASR under various system configurations. It is also observed that the ASR performance of the TWR system with unequal numbers of source antennas is more sensitive to the relay location than to the power allocation.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2012.10a
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• pp.583-585
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• 2012

In this paper, we introduce a design method for a broadband planar quasi-Yagi antenna (QYA) for terrestrial digital television (DTV) receiving. The coplanar strip line feeding the driver dipole is connected to a microstrip line and is terminated by short circuit. By appending a wide strip-type director at a location close to the driver dipole, a broadband impedance matching and a gain characteristics in a high frequency region are obtained. The gain characteristics in a low frequency region are improved by adding a reflector formed by a truncated ground plane. To reduce the antenna size, the strip-type dipole and reflector are modified to half bowtie (V)-shaped elements. The effects of various parameters on the antenna characteristics are examined. An antenna, as an design example for the proposed antenna, is designed for the operation in the frequency band of 470-806 MHz for terrestrial DTV. The optimized antenna is fabricated on an FR4 substrate and tested experimentally to verify the results of this study.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2013.10a
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• pp.71-72
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• 2013

In this paper, a design method for a compact slot antenna for 5.8 GHz RFID band (5.725-5.875 GHz) is studied. The proposed slot antenna is size-reduced by bending both ends of the straight slot in "${\Gamma}$"-shape, and a rectangular feed patch is located inside the slot. The effects of slot length, location of feed patch, and width and length of feed patch on the antenna performance are examined. A prototype antenna with optimized parameters for 5.8 GHz band is fabricated on an FR4 substrate and tested experimentally. The experimental results show that the frequency band for a VSWR < 3 ranges 5.72-6.13 GHz (bandwidth 410 MHz), and it corresponds fairly well with the simulated band 5.64-5.97 GHz (bandwidth 330 MHz). The fabricated antenna shows good radiation performance such as maximum power density in both directions normal to the slot plane, and low cross-polarization level of < -20 dB.

• Journal of Navigation and Port Research
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• v.39 no.6
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• pp.473-478
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• 2015

In this paper, we suggest a flexible multiband antenna which can be equipped on an inflatable life-jacket. The antenna can send distress alert and location data of survivors to assist rescue operation when crew or people are in distress. The antenna operate in three frequency bands such as VHF-DSC band (156MHz), COSPAS-SARSAT band (406MHz) and GPS band (1,575MHz). The GPS band is implemented with a square ring-slot planar antenna, the COSPAS-SARSAT band and the VHF-DSC band antenna is implemented by monopole type. In order to give flexibility of substrate to be equipped on life-jacket, FR4-epoxy substrate of thickness 0.2mm is used to make antenna. The reflection coefficients of the fabricated antenna are -8.8dB, -20.4dB and -10.7dB at each bandwidth like VHF-DSC, COSPAS-SARSAT and GPS band, respectively, when people are wearing life-jacket integrated multiband antenna.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.17 no.12
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• pp.2763-2768
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• 2013

In this paper, a design method for a compact slot antenna for 5.8 GHz RFID band (5.725-5.875 GHz) is studied. The proposed slot antenna is size-reduced by bending both ends of the straight slot in "I"-shape, and a rectangular feed patch is located inside the slot. The effects of slot length, location of feed patch, and width and length of feed patch on the antenna performance are examined. A prototype antenna with optimized parameters for 5.8 GHz band is fabricated on an FR4 substrate and tested experimentally to verify the results of this study. The experimental results show that the frequency band for a VSWR < 3 ranges 5.72-6.13 GHz (bandwidth 410 MHz), and it corresponds fairly well with the simulated band 5.64-5.97 GHz (bandwidth 330 MHz). The fabricated antenna shows good radiation performance such as maximum power density in both directions normal to the slot plane, low cross-polarization level of < -20 dB, and realized gain > 0 dBi within the frequency band.

• Journal of Communications and Networks
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• v.9 no.3
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• pp.254-264
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• 2007

A promising approach to improve the performance of mobile location system is the use of antenna arrays in both transmitter and receiver sides. Using advanced array signal processing techniques, such multiple-input multiple-output (MIMO) communication systems can offer more mobile location information by exploiting the spatial properties of the multipath channel. In this paper, we propose a novel approach to determine the position of mobile terminal based on estimated multipath signal parameters using only one base station in MIMO communication systems. This approach intends to minimize the error occurring from the estimation of multiple paths and gives an optimal estimation of the position of mobile terminal by simultaneously calculating a set of nonlinear location equations. This solution breaks the bottleneck of conventional mobile location systems which have to require multilateration of at least three base stations.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.19 no.9
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• pp.1037-1044
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• 2008

Radiation efficiency and antenna gain, in this paper, can be increased by the slot on EMI shield painted on the mobile phone back cover. When the EMI slot which has proper dimension and location is located on the EMI paining area in the phone, the increment of antenna current density due to mutual coupling between the antenna and slot derives increment of antenna efficiency. For the verification of EMI slot effect, we apply the EMI slot to the mobile phone which is operating on GSM/DCS/USPCS/WCDMA quad band, and measure $S_{11}$ and antenna efficiency. It's shown that resonant frequency is not changed and radiation efficiencies to frequency channels by EMI slot are increased from 0.21 % to 8.96 %.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.25 no.11
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• pp.1095-1103
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• 2014

WBAN has received great attention recently due to its versatile applicability. In this paper, antennas suitable for WBAN communication depending on the locations of mobile devices and the manufacturing of a human equivalent phantom are introduced. The effect of the body on the communication performance is largely dependent on the locations of devices. Specifically, the radiation and return loss characteristics of the antenna are greatly influenced by the characteristics of a medium existing in the near-field of an antenna. Thus, the proper WBAN antenna design is important in establishing a successful communication link between the transceivers. To consider the effect of the body on the antenna performance, the human equivalent phantom is also important factor in the WBAN antenna design and measurement. In introduction, categorization of the WBAN communication channel is introduced and antenna characteristics required for each communication channel are described. In the main subject section, several WBAN antenna design examples along with the implementation of the human equivalent phantom are discussed. In conclusion, the factors, which have to be considered in the design process, and future research are mentioned.

• Journal of the Korean Society for Railway
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• v.4 no.3
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• pp.102-109
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• 2001

In this paper, it has a proposal of the RFID reader antenna design that expand the dedicated short-range communication distance between a static object on the ground and a mobile object attached on the moving article. The static reader equipped with micro-processor makes it possible to have a serial communication with a main system, so that much data can be transfer to the main system. An antenna is adjusted in order to a communication, the scale is designed by results values of simulation using matlab. It is achieved to systematically manage logistics, person resource and security system by grasping the information and location of mobile object on the basis that this system receives the information between a static reader and a mobile object tag at 134.2kHz band on real time, also to make it possible the main system to process. Therefore, the reader antenna scale is controlled on the foundation of a magnetic field theory in order to expand a recognition distance of reader and tag, so that can be optimistically recognized with minimizing the direction influence of reader and tag.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.37 no.1C
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• pp.1-7
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• 2012

At the industrial work site, the manufacturing process is being automated to improve work efficiency. However, it is often difficult to automate the entire manufacturing process, and there are spaces in which workers there are constantly exposed to danger. To protect such workers from the danger, this paper studied a worker safety management system for the industrial work site which uses a location recognition system and which is based on the Ubiquitous-Wireless Sensor Network (U-WSN). Using wireless signals, the distance between two devices can be measured and the location of a worker can be calculated using triangularization in 3-D. But at the industrial work sites where there are a lot of steel and structures, errors occur due to signal reflection and multi-path, etc., which makes it difficult to get the accurate location. To address this problem the following was done: first, a circular polarization patch antenna appropriate to the work site was used to reduce the degree of error that may occur from the antenna emission pattern and the particular Line of Sight (LOS); second, a 3-D localization technique and a filtering algorithm were used to improve the accuracy of location determination. The developed system was tested by using it on a wharf crane to validate its accuracy and effectiveness. The proposed location recognition system is expected to contribute greatly in ensuring the safety of workers at industrial work sites.