• Journal of the Korea Institute of Information and Communication Engineering
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• 제17권1호
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• pp.158-165
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• 2013

In this paper, a new circuit topology of an ultra-wideband (UWB) 3.1-10.6GHz CMOS low noise amplifier is presented. The proposed UWB low noise amplifier is designed utilizing RC feedback and LC filter networks which can provide good input impedance matching. In this design, the current-reused topology is adopted to reduce the power consumption and the inductor-peaking technique is applied for the purpose of bandwidth extension. The performance results of this UWB low noise amplifier simulated in $0.18-{\mu}m$ CMOS process technology exhibit a power gain of 14-14.9dB, an input matching of better than -10.8dB, gain flatness of 0.9dB, and a noise figure of 2.7-3.3dB in the frequency range of 3.1-10.6GHz. In addition, the input IP3 is -5dBm and the power consumption is 12.5mW.

• The Journal of the Korea institute of electronic communication sciences
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• 제11권9호
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• pp.841-848
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• 2016

In this paper, a microstrip-fed dual-band monopole antenna with DGS(: Defected Ground System) for WLAN(: Wireless Local Area Networks) applications was designed, fabricated and measured. The proposed antenna is based on a microstrip-fed structure, and composed of two strip lines and DGS structure and then designed in order to get dual band characteristics. We used the simulator, Ansoft's High Frequency Structure Simulator(: HFSS) and carried out simulation about parameters W2, L10, W3, and DGS to get the optimized parameters. The proposed antenna is made of $21.0{\times}36.0{\times}1.6mm3$ and is fabricated on the permittivity 4.4 FR-4 substrate. The experiment results are shown that the proposed antenna obtained the -10 dB impedance bandwidth 700 MHz(2.10~2.80 GHz) and 1,780 MHz(5.02~6.80 GHz) covering the WLAN bands. Also, the measured gain and radiation patterns characteristics of the proposed antenna are presented at required dual-band(2.4GHz band/5.0GHz band), respectively.

• The Journal of Korean Institute of Communications and Information Sciences
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• 제22권11호
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• pp.2573-2584
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• 1997

In this paper, Ca, Sn substitute YIC(Yttrium Iron Garnet) ceramics were fabricated with Al substitutions in Fe sites. The strip-line circulator was designed and the properties of fabricated ciculator were measured. When the electric, magnetic and microwave properties were measured in Ca, Sn substituted YIG with Al subsititions, the relative permittivity and perfmeability in microwave frequencies were 15.623 and 0.972, repectively. For $Y_{2.4}Ca_{0.3}Sn_{0.3}Fe_{5-x}Al_xO_{12}$ garnet ceramics sintered at $1450^{\circ}C$, the ferrimagnetic resonance line width $\Delta{H}$) of 42 Oe and the saturation magnetization of 487 G were measured at 10 GHz. The strip-line circulator was simulated with 3-D FEM(Finite Element Method) software and designed to have insertion loss of 0.8dB, return loss of 25dB, isolation of 35dB at the center frequency of 1.9GHz. The fabricated strition loss of 0.8B, reture loss of 25dB, isolation of 35dB at the center frequency of 1.9GHz. The fabricated strip-line junction circulator using above YIG ceramics had insertion loss of 0.869dB, return loss of 26.955dB, isolation of 44.409dB at the center frequency of 1.9GHz.

• Journal of the Optical Society of Korea
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• 제14권1호
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• pp.28-32
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• 2010

We demonstrate binary spectral phase coded waveform discrimination at 10 GHz for narrow band optical code-division multiple-access (NB-OCDMA) via direct electrical detection without using any optical hard-limiter. Only 9 phase-locked, 10 GHz spaced, spectral lines within a 100 GHz spectral window are used for the phase coding. Considerably high contrast ratio of 5 between signal and multiuser access interference noise can be achieved for $4{\times}10\;G\;pulse/sec$ timing coordinated OCDMA at a simple electrical receiver with 50 GHz bandwidth.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• 제10권4호
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• pp.628-635
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• 1999

At center frequency of 11.85 GHz, wideband left-handed circularly polarized microstrip array antenna is designed with the method of sequential ratation based on $2\times2$ radiation elements($0^{\circ}$, $45^{\circ}$, $90^{\circ}$, $135^{\circ}$ phase delay). Its return loss, axial ratio bandwidth, radration pattern, and gain are compared with those adopting sequential rotation based on $1\times2$ radiation elements($0^{\circ}$, $90^{\circ}$, $180^{\circ}$, $270^{\circ}$phase delay). The $8\times8$ array is manufactured and measured. The results show that 10 dB return loss bandwidth is 10.51~12.74GHz(18.82%) which is 1.57 times wider than the case using $1\times2$ sequential rotation method, 3 dB axial ratio bandwidth is 11.43~12.5 GHz(9.03%) which is 1.25 times as wide as that using $1\times2$ sequential rotation method and the antennal gain is 25.4 dB. The results of mesurements are almost similar to those of simulation.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• 제28권10호
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• pp.761-768
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• 2017

In this paper, to implement the electromagnetic wave environment and solve electromagnetic compatibility(EMC) problem, miniaturization of ultra-wide band log periodic dipole antenna for measurement was investigated. In addition, in oder to improve the signal-to-noise ratio in high frequency band, balun was connected to the antenna to stabilize the operation of the differential mode antenna and the single mode coaxial cable. To minimize the total size and to increase bandwidth of the antenna, a fat dipole structure was used for the resonance frequency band below 4 GHz and a general dipole shape was used for that above 4 GHz. The bandwidth of the proposed antenna was represented from 0.6 GHz to 8.0 GHz with a ratio bandwidth of 12.3 : 1. Measured peak gain varies from 5.7 dBi to 9.1 dBi, and a half power beamwidth was presented from $29.4^{\circ}$ to $100.2^{\circ}$ in operating range.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• 제27권10호
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• pp.941-944
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• 2016

This paper proposes 24 GHz power amplifier for automotive collision avoidance and surveillance short range radar using Samsung 65-nm CMOS process. The proposed circuit has a 2-stage differential power amplifier which includes common source structure and transformer for single to differential conversion, impedance matching, and power combining. The measurement results show 15.5 dB maximum voltage gain and 3.6 GHz 3 dB bandwidth. The measured maximum output power is 13.1 dBm, input $P1_{dB}$ is -4.72 dBm, output $P1_{dB}$ is 9.78 dBm, and maximum power efficiency is 17.7 %. The power amplifier consumes 74 mW DC power from 1.2 V supply voltage.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• 제16권9호
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• pp.932-940
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• 2005

In this paper, a planar half-circle shape ultra-wideband(UWB) antenna fed by CPW is designed, fabricated and measured for UWB communications. Within the UWB band(3.1 GHz${\~}$10.6 GHz), 5.15 GHz${\~}$5.825 GHz frequency band is used by IEEE 802.1la WLAN applications. It may be necessary to notch out this band to avoid interference with IEEE 802.1la WLAN. Therefore, we have proposed three kinds of UWB antennas having a notch function, such as a rectangular slot, a hat-shaped slot a circle-shaped slot. The notch frequency of the proposed antenna can be adjusted by controlling the slot length or slot width. From the measured results, the proposed antennas show a good gain flatness except the IEEE 802.1la WLAN frequency band and have a reasonable agreement with simulated results.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• 제29권1호
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• pp.1-9
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• 2018

In this paper, we propose a film-type dual-band frequency selective structure for improving the wireless communication environment in a building. The proposed frequency-selective structure is a miniaturized structure that can control the resonant frequencies of 2.4 GHz and 5 GHz dual band through simple design parameters. We fabricated the frequency-selective surface by screen printing using conductive ink on a thin transparent film and confirmed its performance by measurement. We analyzed the attenuation performance of the unnecessary signal from the outside when the frequency-selective structure designed using the software to analyze the propagation environment performance is applied to the building. To verify the analytical results, the signal strength of the indoor environment was measured by applying the frequency-selective film fabricated on the inner wall of the actual building. The measurement results show that the dual-band frequency-selective film has 29.4 dB and 15.94 dB attenuation performance in the 2.4 GHz and 5 GHz, respectively.

• Journal of the Institute of Electronics Engineers of Korea TC
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• 제46권9호
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• pp.60-65
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• 2009

In this paper, we present a compact Ultra-Wideband band-pass later with notched band at fireless-LAN band using a band-pass and band-notch 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, and an embedded open-stub structure is used to get the notched filter. Our proposed band-pass filter can be much smaller than a cascaded filter. As a result of measurement, the insertion loss is less than 0.7dB throughout the pass-band of $2.21GHz{\sim}10.92GHz$, the return loss is more than 17dB and the group delay maximum variation is 0.24ns and a notched band is at $5.3GHz{\sim}5.7GHz$.