• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.17 no.9 s.112
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• pp.874-882
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• 2006

We surveyed the international and national spectrum & technical standardization trends of extremely adaptive frequency bands $57\sim64GHz$ that can provide 1 Gbps bit-rate ultra broadband service in above 30 GHz millimeter waves, and analyzed service scenarios and the characteristics of these bands, As a result of these analysises, 1 Gbps ASK channel bandwidth needs 2.5 GHz and total bandwidth calculated 7 GHz for dual FDD. finally, we proposed the nationally suitable allocation plan of millimeter wave bands $57\sim64GHz$.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.44 no.8
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• pp.42-50
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• 2007

This paper presents design methods for dual-frequency(2.4/5.8GHz) active receiving antennas. The proposed active receiving antennas are designed to interconnect the output port of a wideband antenna to the input port of an active device of High Electron Mobility Transistor directly and to receive RF signals of 2.4GHz and 5.2GHz simultaneously where the impedance matching conditions are optimized by adjusting the length of $1/20{\lambda}_0$(@5.8GHz) CPW transmission line in the planar antenna The bandwidth of implemented dual-frequency active receiving antennas is measured in the range of 2.0GHz to 3.1GHz and 5.25GHz to 5.9GHz. Gains are measured of 17.0dB at 2.4GHz and 15.0dB at 5.2GHz. The measured noise figure is 1.5dB at operating frequencies.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.19 no.6
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• pp.640-646
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• 2008

Design procedure of corrugated horn antenna for the mm-wave frequency range is presented, and hybrid condition in horn is calculated. In this paper, corrugate profiles of horn which satisfy both transition to balanced hybrid condition and fabrication possibility under the mm-wave short wavelength are obtained. Electromagnetic fields inside horn and corrugation are derived by the cylindrical mode theory. Propagation characteristics in the horn are calculated by the mode impedance matching method with boundary conditions, and radiation fields are obtained by the Kirchhoff-Hyugen principle to the horn aperture fields. A mm-wave corrugated horn antenna which operates on $85{\sim}115GHz$ is fabricated by electric forming method. Measurements show that VSWR is under 1.3:1 over whole band and the half power beamwidth on radiation pattern 9.2, 9.16 and 9.02 degree on 85, 100 and 110 GHz are agree well with theoretical calculation.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.23 no.9
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• pp.1058-1064
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• 2012

In this paper, an absorber based on metamaterial is proposed to improve the isolation of conventional WCDMA indoor repeater antenna. The proposed absorber is composed of Double Split Ring Resonators(DSRRs) and Complementary Spiral(CS) structure. The proposed absorber based on metamaterial is $9.6mm{\times}9.6mm{\times}1.2mm$ and absorption is about 94 % at 2.2875 GHz. The proposed antenna, which proposed absorber is applied to conventional WCDMA indoor repeater antenna, has isolation over 85 dB. Isolation is improved more than 10 dB compared with the conventional antenna. The VSWR is lower than 2 at WCDMA band from 1.92 GHz to 2.17 GHz. The radiation patterns are $60^{\circ}{\pm}10^{\circ}$ E-plane and H-plane, respectively. And, the gain is more than 6 dBi. The volume of proposed antenna with absorber based on metamaterial is $90mm{\times}90mm{\times}44.8mm$.

• Journal of IKEEE
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• v.7 no.1 s.12
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• pp.88-96
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• 2003

In this paper, We designed and implemented a linear high-power amplifier which can be used for the commercial service in band of $1.9GHz(1.93{\sim}1.99GHz)$ at U.S.A. The output power of the implemented linear high power amplifier is 25W. In order to satisfy IMD characters decided by FCC, the Feedforward linearization techniques has been used. The used feedforward method has improved the IMD characteristics from 10.51dBc to 19.01dBc in each power level from 1W(30dBm) to 25W(44dBm). The IMD level of the final output shows from minimum 64.84dBc to maximum 68.17dBc. Because this good characteristics of IMD, the LPA is expected to use as a commercial product of PCS base station.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.18 no.6
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• pp.835-840
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• 1993

In this paper a FET mixer is designed realized by small-signal S-parameter using microwave CAD, LINMIC + at Ku-band. The mixer has conversion gain 9.88dB at 14GHz RF, 1GHz IF, and + 1dBm LO imput. The maximum conversion gain is obtained 11.71dB at 1.1GHz. The result shows that the FET mixer does not need pre-and/or IF amplifier. The mixer maintains the desired conversion gain with low LO power level. The conversion gain of the mixer is higher than the available gain of a amplifier, which is experimentally verified.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2002.05a
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• pp.227-229
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• 2002

In this paper, we report on a microstrip line voltage controlled tunable bandpass filter. We used the characteristic the relative dielectric constant of thin film ferroelectrics depends on the applied dr voltage. we designed using Au/BSTO/MgO/Au structure. We cascaded many resonators for large furling range sustaining 1 GHz renter frequency, narrow band, low IL ($\leq$4 dB). We could design the BPF of which center frequency is 16 GHz, 1.9 GHz tuning range, the narrow bandwidth within 800 MHz, low insertion loss less than 3 dB by adjusting the gap of 3 cascaded resonators.

• Journal of the Korean Institute of Telematics and Electronics
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• v.18 no.6
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• pp.23-29
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• 1981

By using a slot-line in combination with microstrip lines, a coplanar wide-band balun is designed and fabricated. The slot-line of balun junction is compensated to be operated in C-band(4~8GHz), and therefore the results are agreement with theoritical prediction. Experimental data are given for a 3-section Chebyshev transformer-matched balun with a balanced-to-unbalanced line impedance ratio of 2 : 1. A bandwidth from 3.5GHz to 7.0GHz is obtained with V.S.W.R. of below 1.2 : 1. Maximum insertion loss is measured as 0.9dB, and the phase difference varies linearlly within 180$^{\circ}$$\pm$5$^{\circ}$.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.16 no.9 s.100
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• pp.957-963
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• 2005

This paper presents technique of wideband TIA for optical communication systems using TSMC 0.25 ${\mu}m$ CMOS RF-Mixed mode. In order to improve bandwidth characteristics of an TIA, we use active inductor shunt peaking to cascode and common-source configuration. The result shows the 37 mW and 45 mW power dissipation with 2.5 V bias and 61 dB$\Omega$ and 61.4 dB$\Omega$ transimpedance gain. And the -3 dB bandwidth of the TIA is enhanced from 0.8 GHz to 1.45 GHz in cascode and 0.61 GHz to 0.9 GHz in common-source. And the input noise current density is $5 pA/\sqrt{Hz}$ and $4.5 pA/\sqrt{Hz}$, and -10 dB out put return loss is obtained in 1.45 GHz. The total size of the chip is $1150{\times}940{\mu}m^2$.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.46 no.5
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• pp.49-54
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• 2009

This paper describes implementation of the 1.9GHz RF frequency synthesizer with $0.18{\mu}m$ silicon CMOS technology being used as an application of the USN sensor node transceiver modules. To get good performance of speed and noise, design of the each module like VCO, prescaler, 1/N divider, fractional divider with ${\Sigma }-{\Delta}$ modulator, and common circuits of the PLL has been optimized. Especially to get good performance of speed, power consumption, and wide tuning range, N-P MOS core structure has been used in design of the VCO. The chip area including pads for testing is $1.2{\times}0.7mm^2$, and the chip area only core for IP in SoC is $1.1{\times}0.4mm^2$. The test results show that there is no special spurs except -63.06dB of the 6MHz reference spurs in the PLL circuitry. There is good phase noise performance like -116.17dBc/Hz in 1MHz offset frequency.