• Journal of the Korean Institute of Telematics and Electronics
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• v.27 no.11
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• pp.77-82
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• 1990

The temperature and the composition dependence of the dielectric properties of the solid solution materials in the system $xBa(Zn_{1/3}Nb_{2/3})O_{3}\[BZN]-(1-x)\Sr(Zn_{1/3}Nb{2/3)O_{3}\[SZN]$ at microwave frequency was studied. The dielectric constant and unloaded Q were $40.5{\pm}0.5,5980{\pm}100$ respectively for BZN at 10 GHz and $36.9{\pm}0.5,2700{\pm}100$ for SZN at 10.2GHz. The temperature coefficient of the resonant frequency was $+27.5ppm/{\circ}C$ for BZN and $-39.1ppm/{\circ}C$ for SZN. The results also showed that 0.3 BZN-0.7 SZN is the most temperature-stable composition among xBZN-(1-x) SZN solid solutions. In this case, the dielectric constant, the unloaded Q and $\tau_{f}$ at 9.8GHz were $41.5{\pm}0.2,2920{\pm}100$ and $-3.5ppm/{\circ}C$, respectively.

• Journal of Navigation and Port Research
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• v.35 no.4
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• pp.299-302
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• 2011

In this letter, the effect of quality factor on center frequency deviation in miniaturized coupled line bandpass filter (BPF) with diagonally end-shorted at their opposite sides and lumped capacitors is theoretically analyzed. The miniaturized BPF of a two-stage structure with two types of quality factors in standard CMOS process was designed and manufactured at 5.5 GHz. The die area of BPF was $1.44{\times}0.41\;mm^2$. The measured center frequency of BPF with a quality factor of 4.9 was deviated from 5.5 GHz to 4.7 GHz. The one with 14.8 was shifted to 5GHz. The theoretical and measured results validate that quality factor influences the center frequency shift of BPF.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.53 no.8
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• pp.443-446
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• 2004

In this paper, a multi-band ceramic chip antenna for WLAN(Wireless LAN) applications is designed. The design target is to obtain 0 dBi of coverage gain with omni directional radiation pattern. The antenna is fabricated using Low Temperature Co-fired Ceramic(LTCC) technology. The size of the chip antenna is $2.2{\times}9.65{\times}1.02$mm. The measured antenna gain is 1 dBi at 2.44 GHz and 0.5 dBi at 5.5 GHz. The omni directional radiation pattern for the two operating bands is obtained. The measured bandwidth(S11=-10 dB) are 90 MHz at 2.44 GHz and 1280 MHz at 5.5 GHz respectively

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.10 no.3
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• pp.74-78
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• 2011

In this paper, the bandpass filter for ITS system of 5.8 GHz is proposed by using the dual-mode resonator with the radial stub. As alternating the open stub with the radial stub, the size of the dual mode resonator can be reduced about 39.6% and the out-of-band characteristics of the bandpass filter using dual mode resonator can be enhanced from 19.4 dB to 29.1 dB by using the stub of $6.9{\Omega}$ i.e. realized by parallel two radial stubs with $60^{\circ}$ angle. The fabricated bnadpass filter using the dual mode resonator has the center frequency of 5.72 GHz with the fractional bandwidth of 4.1%. Also, the filter has the insertion loss and return loss of 1.79 dB and 19.4 dB, respectively.

• Journal of the Institute of Electronics and Information Engineers
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• v.49 no.9
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• pp.270-275
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• 2012

This paper describes design of a variable-N frequency synthesizer for RF PLL with $0.13{\mu}m$ silicon CMOS technology being used as an application of the UWB system like MBOA. To get good performance of speed and noise super dynamic circuits was used, and to get variable-N division ratio MOSFET switching circuits was used. Especially to solve narrow bandwidth problem of the dynamic circuits load resistance value of unit divider block was varied. Simulation results of the designed circuit shows very fast and wide operation characteristics as 5~26GHz frequency range.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.2 no.2 s.3
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• pp.65-72
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• 2003

In this work a 6-stage hybrid power amplifier which can be used for the wireless communication systems for MMC(hficrowave Micro Cell) and ITS wireless communication system is designed and fabricated. Ihe power amplifier's each stages was fabricated Hetero-junction Power FET of bare chip type and an alumina substrate with $\varepsilon_{r}$=9.9 and 15-mil thickness. The measured results of power amplifier module showed 33.2$\~$36.5 dB small signal gain, 33.0$\~$34.0 dBm output power at forward frequency (17.6 GHa $\~$ 17.9 CHz) and 36.0$\~$37.0 dB small signal gain, 33.0$\~$34.5 dBm output power at reverse frequency (19.0 GHz $\~$19.2GHz).

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.44 no.9
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• pp.25-33
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• 2007

In this paper, the high isolation and wideband 94 GHz MIMIC(Millimeter-wave Monolithic Integrated Circuit) single balanced cascode mixer was designed and fabricated. Also, we designed and fabricated a 3 dB tandem coupler which has a high isolation and wideband characteristic. The single balanced resistive mixer which does not require an external IF balun was designed using the 0.1 ${\mu}m$ InGaAs/InAlAs/GaAs metamorphic HEMT(High Electron Mobility Transistor). The DC characteristics of MHEMT's are 665 mA/mm of drain current density, 691 mS/mm of maximum transconductance. The current gain cut-off frequency($f_T$) is 189 GHz and the maximum oscillation frequency($f_{max}$) is 334 GHz. A 94 GHz single balanced cascode mixer was fabricated using our 0.1 ${\mu}m$ MHEMT MIMIC process. From the measurements, the fabricated couplers showed wideband characteristics. The conversion loss of single balanced cascode mixer was 9.8 dB at an LO power of 10.9 dBm. The LO to RF isolation of single balanced cascode mixer was 29.5 dB at 94 GHz. We obtained in this study a higher LO-RF isolation compared to some other single balanced mixers.

• Journal of Electrical Engineering and Technology
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• v.9 no.6
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• pp.2019-2024
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• 2014

This paper presents a method to optimize the design of a planar-type antenna and reduce the number of design parameters for rapid computation. The electromagnetic characteristics of the structure are analyzed, and Taguchi method is used to identify critical design parameters. Adaptive particle swarm optimization, which has a faster convergence rate than particle swarm optimization, is used to achieve the design goal effectively. A compact dual-band USB dongle antenna is tested to verify the advantage of the proposed method. In this case, we can use only five selected geometrical parameters instead of eighteen to accelerate the optimization of the antenna design. The 10 dB bandwidth for return loss ranges from 2.3 GHz to 2.7 GHz and from 5.1 GHz to 5.9 GHz, covering all the WiBro, Bluetooth, WiMAX, and 802.11 b/g/n WLAN bands in both simulation and measurement. The optimization process enables the antenna design to achieve the required performance with fewer design parameters.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.23 no.10
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• pp.1240-1247
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• 2019

In this paper, we designed a four-band antenna that can be applied to WLAN and WiMAX systems by designing a microstrip feeding structure, four branch lines and a slit on the ground plane. The proposed antenna is designed with a size of 16.0 mm (W1) × 48.0 mm (L8) on a dielectric substrate of 18.0 mm (W) × 50.0 mm (L) × 1.0 mm(h). and a slit of 2.9 mm (W7) × 4.0 mm (L7) is inserted into the ground plane of 18.0 mm (W) × 18.7 mm (L6). Based on -10 dB production and measurement results, it obtained 60.8 MHz (8,730~9,338 MHz), 310 MHz (2.33~2.64 GHz) in the 2.4 GHz band, 420MHz (3.39~3.81 GHz) in the 3.4 GHz band, and 2,070 MHz (4.62~6.69 GHz) in the 5.0 GHz. In addition, the gain and radiation pattern characteristics of the quadrant band are measured from the measurement results anechoic chamber.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.23 no.10
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• pp.90-99
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• 2009

In this paper, we proposed the new class-E frequency multiplier design that include the highest efficient characteristics. The proposed frequency multiplier is designed for 5.8[GHz] output using the frequency multiplier about 2.9[GHz] input signal. And studying in this paper is for the design and the implementation of the class E frequency multiplier. For the result, the maximum highest efficient characteristics 32[%] which is with output power 24.5[dBm] and 8.5[dB], is shown with frequency multiplier for the 2.9/5.8[GHz] class E. And we applied the linear method to the implemented class E frequency multiplier. As a result, the output spectrum for the linear is upgrade to 12[dB], 12[dB], 13[dB] of the ACPR characteristics on the +11[MHz], +20[MHz], +30[MHz] offset frequency in the center frequency. The result is satisfied with the 3.83[%] of the lineared EVM for the 64-QAM modulated method with the 54[Mbps] transmission velocity. In this paper, we show that the good compensation result of the linearity and the efficiency through the digital pre-linear method of the distortion with the frequency multiplier. Therefore, we suggested the frequency multiplier method are applying to WLAN, cellular, PCS, WCDMA, and etc.