• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.31 no.1A
• /
• pp.58-64
• /
• 2006

A 900-MHz band transceiver has been developed for RFID reader applications. In the transmitter, a GaAs SPST switch is used for high speed switching and low power consumption. In the receiver, a double balanced mixer is used to compress even-harmonic products. The ASK demodulator which consists of an active filter and comparator is used to reject the unwanted in band interferers. The transceiver produces a maximum transmitting power of 30 dBm and exhibits an 5 m communication range with a 6-dBi gain antenna.

• The Journal of the Korea Contents Association
• /
• v.7 no.11
• /
• pp.102-110
• /
• 2007

In this paper, a portable RFID reader which operated in 900MHz UHF band is designed and fabricated and the characteristics of the manufactured portable RFID reader is analyzed through measurement. Analysis of measurements results is achieved based on EPC Class 0 standards that proposed by EPC Global. The proposed RFID reader communicate with tags about 11kbps speed, and have 20 dBm for its maximum RF output power. The proposed portable RFID reader can recognize maximum 68 tags per second, and when reader's output power is 20 dBms, maximum recognition distance is 30cm. And the total size of implemented RFID reader is $71mm{\times}55mm$, that is the maximum 90%, minimum 14% reduced size compared with marketed product.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.2 no.3
• /
• pp.359-365
• /
• 1998

The portable two way radio telephone amongst GMDSS equipment in the vessel is very important portable wireless one for search and rescue in distress situation. Although the portable two way radio telephone must be equipped with in the vessel by IMO & RR, other kinds of wireless tranceivers are widely used to communicate with crew members who are separately appointed at bridge forecastle and poop in leaving or arriving at the port, passing through a narrow canal or voyaging in the foggy weather, Most of those wireless tranceivers except portable two way radio telephone are allocated at 27MHz band with PTT simplex system that makes crew members difficult to work effectively in the vessel. In this research 900MHz band FDD(frequency duplex division) tranceiver system is studied to help crew members in the vessel to communicate with themselves freely and to work easily meanwhile with simple operation. 900MHz band FDD tranceiver system uses one chip FM frontend IC to realize the miniaturization and downsizing of tranceiver and small size head set attached to helmet. The credibility of this research's result is highly evaluated by circuit analysis with computer aided simulation, and partly modified 900MHz band cordless phone circuit.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 1998.05a
• /
• pp.365-370
• /
• 1998

The portable two way radio telephone amongst GMDSS equipment in the vessel is very important portable wireless one for search and rescue in distress situation. Although the portable two way radio telephone must be equipped with in the vessel by IMO RR, other kinds of wireless tranceivers are widely used to communicate with crew members who are separately appointed at bridge forecastle and poop in leaving or arriving at the port, passing through a narrow canal or voyaging in the foggy weather. Most of those wireless tranceivers except portable two way radio telephone are allocated at 27MHz band with PTT simplex system that makes crew members difficult to work effectively in the vessel. In this research 900MHz band FDD(frequency duplex division) tranceiver system is studied to help crew members in the vessel to communicate with themselves freely and to work easily meanwhile with simple operation. 900MHz band FDD tranceiver system uses one chip FM frontend IC to realize the miniaturization and downsizing of tranceiver and small size head set attached to helmet. The credibility of this research's result is highly evaluated by circuit analysis with computer aided simulation. and partly modified 900MHz band cordless phone circuit.

• 한국정보통신설비학회:학술대회논문집
• /
• 2007.08a
• /
• pp.432-435
• /
• 2007

In this paper, a dual band microstrip patch Antenna is designed for RFID Application. The antenna shows a good performance at the frequencies, 900MHz and 2.45GHz for the radiation characteristics and input impedance matching, as well. The reflection factor is lower than -25dB and a good directivity higher than 5dB is achieved for both frequency.

• Proceedings of the Korea Contents Association Conference
• /
• 2011.05a
• /
• pp.33-34
• /
• 2011

본 논문은 900MHz 대역의 RFID를 이용하여 고속도로 자동 요금징수 시스템을 개발하고, 차량에 부착한 태그를 RFID 리더가 인식하는 효율을 높이기 위하여 최적의 태그부착위치와 안테나 설치위치에 대하여 연구하고 속도에 따른 인식률을 연구 하였다.

• Journal of the Korea Safety Management & Science
• /
• v.8 no.4
• /
• pp.119-127
• /
• 2006

This paper deals with the middleware and S/W development of real time automatic attendance check management system using ubiquitous 900Mhz RFID(Radio Frequency Identification). This system supports the real time automatic attendance check and necessary data processing in class management. We expect to decrease the effort for class management and to upgrade the status of real time management of class.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.11 no.1
• /
• pp.76-83
• /
• 2000

A 2-pole tunable bandpass filter was design and fabricated using ceramic coaxial resonators and varactor diodes for UHF band. By inspection of frequency characteristics of the T-and $\pi$-type inverter equivalent circuits, we can design a two-pole tunable BPF with only two varactors. The measured data of the filter show 800 MHz-900 MHz tunable center frequency range, 4.5 dB insertion loss, 0.5 dB passband ripple and at least 15 dB return loss, which agree well with the simulated results.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
• /
• 2005.11a
• /
• pp.235-240
• /
• 2005

This paper presents a dual band circularly polarized microstrip patch antenna. The antenna consists of two corner truncated patches implemented in one plane and single feed point. The input signal is directly excited to the patch 2 and the patch 1 is fed from patch 2 by coupling between two patches. The antenna is operated at 900 MHz and 2.45 GHz bands and has the right hand circularly polarized radiation pattern at all. The measured gains of the antenna are 2.95 dBic at 900 MHz band and 4.6 dBic at 2.45 GHz band.

• Journal of the Korean Institute of Telematics and Electronics A
• /
• v.31A no.10
• /
• pp.71-78
• /
• 1994

We have developed GaAs power metal semiconductor field effect transistors (MESFETs) for 4.7V operation under 900 MHz using a low-high deped structures grown by molecular beam epitaxy (MBE). The fabricted MESFETs with a gate widty of 7.5 mm and a gate length of 1.0.mu.m show a saturated drain current (Idss) of 1.7A and an uniform transconductance (Gm) of around 600mS, for gate bias ranged from -2.4 V to 0.5 V. The gate-drain breakdown voltage is measured to be higher than 25 V. The measured rf characteristics of the MESFETs at a frequency of 900 MHz are the output power of 31.4 dBm and the power added efficiency of 63% at a drain bias of 4.7 V.