• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 2003.09b
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• pp.118-121
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• 2003

Generally, the repeater in CDMA(Code Division Multiple Access) included HPA(HI-Power Amplifier) to amplifier communication signals. Also , HPA contained PD(Predistortor) to maintain the linearization of amplifier characteristics. A configuration component of PD have been used electricity nonlinear devices such that diode. But this diode takes many influences at the circumstance temperature. Consequently, it can't maintain output linearization, and drop the communication quality. The manufacturer set bias of the circuit to the manual at the first out of ware-house low But the Q-point changes according to the change of the high temperature or low temperature. Therefore, we designed a system to maintain the Q-point by FDM(Fuzzy Decision Maker) in this paper.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2003.05a
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• pp.586-589
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• 2003

Repeater is developed. Based on the systems The up-converter of the WCDMA Digital Optic pecifications, the structure of the up-converter is accomplished and its block diagram is drawn. The up-converter is implemented according to these block diagrams. Subsequently the low pass filter, the automatic level controlled attenuator, the frequency synthesizer and other components for the up-converter are designed and implemented, and a main board to integrate these modules is also manufactured. To reduce the noise floor of system and suppress the RF spurious noise, a PCB layout is performed carefully. For each module consisting of the up-converter and the entire system, the performance tests are accomplished to check the performance about the specifications.

• Journal of Institute of Control, Robotics and Systems
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• v.13 no.5
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• pp.462-466
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• 2007

This paper proposes an automatic bandwidth control method for the performance improvement of Binary Amplitude Shift Keying (BASK) system for Giga-Bit Modem in millimeter band. In order to improve the performance of the BASK system with a fixed bandwidth, the proposed method is to adjust a bandwidth of low pass filter in receiver using the fuzzy system. The BASK system consists of a high speed shutter of the transmitter and a counter and a repeater of receiver. The repeater consists of four stage converters, and a converter is constructed with a low pass filter and a limiter. The inputs to the fuzzy system are the reminder and integral of remainder of counter, and output is a bandwidth. We used a Viterbi algorithm to find the optimum detection from the output of the counter. Simulation results showed that the proposed system improves the performance compared to the fixed bandwidth.

• The Journal of the Korea institute of electronic communication sciences
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• v.6 no.2
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• pp.274-279
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• 2011

To increase the performance of mobile communication systems, base statations having beamforming function are released recently. For the proper beamforming function, it is required that each RF paths be calibrated periodically. However, the current calibration method has a problem when the base station is connected to a repeater. In this paper, we report the problem and propose a new calibration method to solve the problem.

• Proceedings of the IEEK Conference
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• 2001.06a
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• pp.185-188
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• 2001

In this paper, we design and implement high-power amplifier with 18 watt for W-CDMA repeater. We simulate microwave circuits using RF simulator, ADS1.3 and optimize the circuit to obtain the linear and high power using Harmonic balance method. Harmonic balance is an excellent method in the analysis of nonlinear system. The HPA is fabricated on tefron substrate($\varepsilon_{{\gamma}}$=3.48, h=0.5mm, T=0.035mm). From the measured result, the HPA has gain of 52dB, 1 dB compression power of 52.8dBm and good ACPR (Adjacent Channel Power Radio) performance.l Power Radio) performance.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2003.10a
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• pp.737-740
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• 2003

SFN (Single Frequency Network) and OCR (On Channel Repeater) are often considered for the efficiency of frequency allotment in digital TV. In this paper, we discuss the performance and evaluate some coverage criterions for SFN and OCR. Also, we propose MATLAB simulator for coverage planning and estimation.

• Journal of the Korean Institute of Telematics and Electronics
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• v.12 no.2
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• pp.28-30
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• 1975

In this paper a new network configuration for two-line four-line connection in telephone transmission system is proposed. It is proved that this network configuration is useful not only in an anti-sidatone circuit for telephone substation but also in a repeater station in the telephone system. It can ba realized in an integrated circuit.

• Journal of electromagnetic engineering and science
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• v.1 no.1
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• pp.43-47
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• 2001

A compact size microstrip antenna element using FR-4 substrate is proposed for use in repeater and base stations. Two stacked patches are aperture-coupled by two split feedlines. Rectangular stubs on the split feedlines are laid under the aperture and have the effect of considerably lowing the magnitude of $S_{11}$ [dB] and broadening impedance bandwidth. The designed structure has been fabricated and measured. Based on 20 dB, the return loss bandwidth is about 16.8% (1.86 GHz~2.20 GHz), which covers the frequency range assigned for IMT-2000 with a large margin. The overall dimension of the proposed antenna structure is 37 mm$\times$41 mm$\times$19mm (very compact). The antenna gain is more than 7.5 dBi over the required frequency range.

• Journal of Advanced Marine Engineering and Technology
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• v.31 no.5
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• pp.575-582
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• 2007

In this paper, a 100 Watt high power amplifier has been implemented and performed evaluation, which is operating at UHF band ($470\;{\sim}\;806\;MHz$) for Digital TV repeater. To achieve increase of bandwidth and high power capability, 3-way power combiner and divider of Wilkinson type was adopted. In order to measure the fabricated 100 Watt power amplifier, the estimation technique function which makes equivalent mask was used. As a result of the measurement, the existence of pilot signal is confirmed and the signal transmitted at the rated output power 100 Watt is brought out the flat feature through 6 MHz bandwidth. and it resulted that its value was less than -47 dB at the edge of radiation channel and less than -110 dB at more than 6 MHz position from channel edge.

• Proceedings of the IEEK Conference
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• 2007.07a
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• pp.105-106
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• 2007

A slot antenna with bazooka balun is designed and implemented for PCS repeater. The proposed antenna improved the return loss and radiation pattern of the slot antenna as combining with the bazooka balun. The antenna was designed by using 3D simulations program, MWS (Microwave Studio). The test result of the slot antenna shows that the return loss is under -10 [dB] for all frequency bands of interests in PCS and maximum gain is about 5.59 [dBi]. And the antenna also shows omni-directional radiation pattern.