• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.10
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• pp.3917-3922
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• 2010

In this paper, 3 stage amplifier MMIC was designed and fabricated with U-band optimized epitaxal pHEMT that produced by large signal characterization and modeling for 60 GHz band. The pHEMT used in this paper, the gate $0.12\;{\mu}m$ length and total gate width of $100\;{\mu}m$, $200\;{\mu}m$ has been modeled using the large signal designed with negative feedback and MCLF instead of MIM capacitor for improving stability. Fabricated MMIC $2.5{\times}1.5mm^2$ size, current about 40 mA, operating frequency 59.5~60.5 GHz, gain 19.9~18.6 dB, input matching characteristics -14.6~-14.7 dB, output matching characteristics -11.9~-16.3 dB and output -5 dBm characteristics were obtained.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.26 no.11
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• pp.1672-1678
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• 2022

In this paper, the relay antenna was designed in consideration of the performance of the 28GHz band 5G mobile communication relay horn antenna, such as radiation pattern and return loss. A horn array for 5G mobile communication repeater was designed by arranging the antenna elements in phase, and the performance was analyzed. Unlike conventional WCDMA (3G) and LTE (4G), in millimeter wave band communication, high path loss occurs between transmission and reception. In the design of a 5G millimeter wave horn antenna, antenna performance such as isolation and gain between antenna elements as well as gain and bandwidth of the antenna must be additionally considered. The antenna gain of the single horn antenna (1×1) and the array horn antenna (2×4) in the 28GHz band is about 10.44d Bi and 19.58dBi, respectively, and the return loss is designed to be less than -18dB. It has proven its validity and has been shown to be suitable for application to 5G mobile communication relay system.

• Proceedings of the IEEK Conference
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• 2003.11c
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• pp.64-67
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• 2003

This paper presents the design of dual-band VCO using PBG structure for IEEE 802.11A/B. By adding switch circuit to the single-band VCO, we could achieve a dual-band VCO. The center frequencies of dual-band VCO are 5.93GHz(-13dBm) and 2.37GHz (3.50dBm). The phase noise is improved about l0dB by using PBG Structure.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.27 no.5C
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• pp.522-529
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• 2002

MMIC circuits in whole receiver system was fabricated based on GaAs pHEMT technology. And a V-band downconverter module was fabricated by integrating these circuits. The downconverter module consists of a LO drive power amplifier which generates 24dBm output power, a low noise amplifier(LNA) which shows 20 dB small signal gain, an active parallel feedback oscillator which generates 1.6 dBm output power, and a cascode mixer which shows over 6dB conversion gain. The good conversion gain performance of our mixer made no need to attach any IF amplifier which grows conversion gain. Measured results of the complete downconverter show a conversion gain of over 20 dB between 57.5 GHz and 61.7GHz without IF amplifier.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.46 no.5
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• pp.162-167
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• 2009

In this paper, we present a compact Ultra-Wideband band-pass filter using a high-pass filter and low-pass filter. The structure of our proposed band-pass filter is very simple and the DGS(Defected Ground Structure) structure is used to get the low-pass filter characteristic. Our proposed band-pass filter can be much smaller than a cascaded filter. As a result of measurement the insertion loss is less than 0.5dB throughout the pass-band of $2.1GHz{\sim}10.56GHz$, the return loss is more than 20dB and the group delay maximum variation is 0.23ns from 0.12ns to 0.35ns.

• Proceedings of the IEEK Conference
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• summer
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• pp.181-184
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• 2004

In this paper, we propose the dual band(2.4GHz and 5GHz) antenna for access point of WLAN(Wireless Local Area Network) which has similar radiation patterns for each band. Simulation results by using HFSS(High Frequency Structure Simulator) for the proposed antenna are presented. The electrical characteristics of the proposed antenna are measured with HP 8510C network analyzer and included. And radiation patterns are measured with rectangular anechoic far field antenna chamber. Measured results show that $S_{11}$ is less than - 14dB and VSWR(Voltage Standing Wave Ratio) is less than 1.5 for all frequency bands of interest. The measured maximum gain for elevation pattern at 2.40GHz is about 2.46dBi at $theta=-78^{\circ}$ and maximum gain for 5.825GHz is about 2.70dBi at $theta=-80^{\circ}.$ And the implemented antenna has good radiation pattern characteristic, therefore, we expect that the implemented dual band antenna is applicable for access point of WLAN.

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

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.22 no.2
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• pp.245-251
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• 2011

In this paper, dual-band bandpass filter by using Pseudo-Interdigital Stepped-Impedance Resonator(PI-SIR) and Open-Loop Ring Resonator(OLRR) is proposed. The first passband and second passband are formed by PI-SIR and the second passband is reinforced by an OLRR. In a PI-SIR the first band and second band are easily and exactly adjusted by characteristic impedance ratio and electrical length ratio. The proposed design method may be confirmed to be useful from fabricated and measured results for dual-band bandpass filter operated at 2.45 GHz and 5.8 GHz.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2015.10a
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• pp.61-62
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• 2015

In this paper, a design method for a dual-band compact slot antenna using SRR(split-ring resonator) conductor is studied. The SRR conductor is loaded inside of a rectangular slot of the proposed antenna for dual-band operation. Final design parameters are obtained by analyzing the effects of the gap between the SRR conductor and slot, and the width of the SRR conductor on the input reflection coefficient and gain characteristics. A prototype of the proposed dual-band slot antenna operating at 2.45 GHz WLAN band and 3.40-5.35 GHz band is designed on an FR4 substrate with a dimension of 30 mm by 30 mm.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.19 no.2
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• pp.145-151
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• 2008

In this paper, a dual band microstrip antenna with similar radiation pattern for the satellite internet service is proposed. The proposed antenna has two Y-shaped slots on the microstrip patch that is fabricated on RO4003 substrate with a dielectric constant of 3.38 and a thickness of 0.508 mm, and operates in the 2 GHz and 5 GHz bands. The size of the antenna is $50\times47.5\times6.5\;mm^3$, and fed by coaxial cable. The measured bandwidths of the antenna are 2.398$\sim$2.507 GHz and 5.458$\sim$5.972 GHz for VSWR<2. The measured gains are 8.92 dBi and 7.74 dBi, respectively, for the lower and upper bands.