• Journal of the Semiconductor & Display Technology
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• v.18 no.1
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• pp.21-24
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• 2019

In this paper, 5.8GHz 25W microwave wireless power transmission system was developed. The transmission system is composed of a signal generator, a 1W drive amplifier, a 25W power amplifier, and a circularly polarized transmission antenna. The receiving system was fabricated with an integrated receiver that combines a circularly polarized receiving antenna, a pass band filter, and an RF-DC converter. And a multi-integrated receiver had twelve parts, including an integrated receiver. Under the conditions, voltage and current were measured for the system at 5cm intervals from a minimum distance of 5cm to a maximum distance of 80cm. The power was calculated for the system. The results of the system are shown in tables and graphs. The power decreases with distance, but the power does not drop sharply due to a multi-integrated receiver.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.19 no.12
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• pp.1445-1454
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• 2008

In this paper, small UWB antenna with band-stop function for mobile handsets is proposed. A gap between radiator and under and side ground is adjusted for small size and broadband. A radiator is folded to the back side of PCB for miniaturization and tapered feeding structure is used to enhance matching characteristic. A antenna clearance has a size of $14{\times}14\;mm^2$ and a size of radiator is $10{\times}7\;mm^2$. It covers all UWB band from 3.15 GHz to 4.75 GHz and from 7.2 GHz to 10.2 GHz for VSWR<2 and has band stop characteristic at 5.8 GHz. A maximum gain is measured as 5.85 GHz. In case conventional handset case is considered, it also covers all UWB and a maximum gain is measured from -2 dBi to -2 dBi.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.20 no.12
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• pp.1264-1271
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• 2009

In this paper, the chip slot antenna which is used for mobile devices and designed for multi-band is proposed. The proposed antenna is comprised of a chip antenna(10 mm$\times$20 mm$\times$1.27 mm) and a system circuit board(30 mm$\times$60 mm$\times$0.8 mm). The chip slot antenna is mounted on the system circuit board and the end of F-type strip line which is patterned on the chip antenna is connected by a via with a ground plane of the system circuit board. So, a chip antenna radiates effectively the energy by transition between a microstrip line of the system circuit board and a open slot structure of the chip antenna. In the results of proposed antenna, impedance bandwidth of 3:1 VSWR(-6 dB return loss) is 1.98 GHz(1.61~3.59 GHz) and 0.8 GHz(5.2~6 GHz). So, it can cover multi-band of DCS, PCS, UMTS, WLAN. The proposed antenna can be applied to mobile devices.

• Journal of IKEEE
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• v.25 no.4
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• pp.721-727
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• 2021

This paper proposes a UWB (Ultar-wideband) impulse generator using the gated ring oscillator. The oscillator and PLL circuits which generate a several GHz LO signal for the conventional architecture are replaced with the gated ring oscillator. Therefore, the system complexity is decreased. The proposed architecture controls the duty of enable signal, which is used for the head switch of ring oscillator. The control of the duty enables to tun off the oscillator during the guard interval and stop wasting the power consumption. The pulse shaping method using the counter makes the small side lobe and preserves the bandwidth regardless of the change on the center frequency. Designed UWB impulse generator could change the center frequency from 6.0 GHz to 8.8 GHz with a digital bit control, while it preserves the bandwidth as about 1.5 GHz.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.43 no.9 s.351
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• pp.17-22
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• 2006

CMOS LC VCO with fast response adaptive frequency calibration (AFC) technique for IEEE 802.11a/b/g WLANs is designed in 1.8V $0.18{\mu}m$ CMOS process. The possible operation is verified for 5.8GHz band, 5.2GHz band, and 2.4GHz band using the switchable L-C resonators. To linearize its frequency-voltage gain (Kvco), optimized multiple MOS varactor biasing tecknique is used. In order to operate in each band frequency range with reduced VCO gain, 4-bit digitally controlled switched- capacitor bank is used and a wide-range digital logic quadricorrelator (WDLQ) is implemented for fast frequency detector.

• 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 Microelectronics and Packaging Society
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• v.15 no.1
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• pp.39-44
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• 2008

In this paper, fully embedded 2.4GHz WLAN band pass filter (BPF) was investigated into a multi-layered organic packaging substrate using high Q spiral stacked inductors and high Dk MIM capacitors for low cost RF System on Package (SOP) applications. The proposed 2.4GHz WLAN BPF was designed by modifying chebyshev second order filter circuit topology. It was comprised of two parallel LC resonators for obtaining two transmission zeros. It was designed by using 2D circuit and 3D EM simulators for finding out optimal geometries and verifying their applicability. It exhibited an insertion loss of max -1.7dB and return loss of min -l7dB. The two transmission zeros were observed at 1.85 and 6.7GHz, respectively. In the low frequency band of $1.8GHz{\sim}1.9GHz$, the stop band suppression of min -23dB was achieved. In the high frequency band of $4.1GHz{\sim}5.4GHz$, the stop band suppression of min -l8dB was obtained. It was the first embedded and the smallest one of the filters formed into the organic packaging substrate. It has a size of $2.2{\times}1.8{\times}0.77mm^3$.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2002.11a
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• pp.148-150
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• 2002

In this paper, a 5-coupled BPF with teflon substrate is presented. In general, for less than 1 GHz frequency, the narrow bandwidth as well as the good characteristic in the rejection frequency band could be realized using lumped elements. However, for higher than 1 GHz frequency, the distributed elements such as microstrip lines need to be used for the design of the desired BPF For less than 2 GHz, the FR4 shows good filter characteristic at low cost. However, in the range of 2 GHz ~ 10 GHz, the filters with FR4 show a big difference between simulation and measurement results. Thus, in such a high frequency region, the teflon is more preferred to the FR4. The center frequency (fc) of the proposed filter is 2.3 GHz, the insertin loss (IL) is 1.2 dB, the return loss (RL) is 30 dB, bandwidth (BW) is 100 MHz, and the size is 8.3 cm $\times$ 4.9 cm.

• Korean Journal of Optics and Photonics
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• v.14 no.4
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• pp.351-354
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• 2003

We present a 12.5-GHz interleaved bidirectional ultra-dense wavelength-division-multiplexing transmission over a conventional single mode fiber of 80 km achieving spectral efficiency as high as 0.8-bit/s/Hz. The beat-frequency-locking method is used to stabilize the channel frequency within $\pm$200 MHz error. To facilitate the identification of multiple beat frequency signals, we use a radio-frequency spectrum analyzer. The bidirectional transmission penalty is about 0.3 dB compared with the unidirectional transmission over the same fiber.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.13 no.8
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• pp.827-833
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• 2002

In this paper, a microstrip array antenna for LMDS(Local Multipoint Distribution Service) receiver with corporate feeding network using Chebyshev polynomials is proposed to get the high gain and low side lobe level. The Chebyshev array method is proposed to design the corporate feeding network. LMDS uses 24~27 GHz microwave frequency band to send and receive broadband signals. Measured antenna shows 23.4 dBi gain, 24.96 GHz center frequency, -29.15 dB return loss and 1.2 GHz bandwidth.