• 대한전자공학회논문지TC
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• 제42권1호`
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• pp.119-123
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• 2005

본 논문에서는 이중 T자 모형의 공진 주파수 이동이 용이한 마이크로스트립 안테나와 새로운 구조를 제안하고 제작 였다. 안테나 구조는 스터브 안테나구조를 응용한 광 대역 이중 T자형 마이크로스트립 안테나이며 CPW급전 방식을 사용하였다. 이중 스터브간의 거리를 조절하여 주파수 제어가 용이한 광 대역 소형 안테나의 특성을 해석 및 측정하였다. 새로운 안테나는 450MHz의 대역폭을 얻었으며, IMT2000(1.8～2.25GHz) 대역에 이용할 수 있는 안테나이다. 안테나구조의 각각 파라미터를 FDTD 알고리즘을 이용하여 해석하였다.

• 한국전자통신학회논문지
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• 제13권2호
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• pp.291-298
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• 2018

본 논문에서는 역 F형 안테나 구조를 변형시키고 CPW급전 방법을 적용함으로써 역 F형 안테나의 단점인 협대역 특성을 개선하고, 소형 그리고 저자세의 구조적인 장점을 살리는 안테나를 제안하고자 한다. 실험 결과 중심주파수 3GHz에서 약 40%의 광대역 특성이 있음을 보여, 기존 역 F형 안테나의 단점인 협대역 특성을 개선할 수 있음을 알 수 있었다. 방사패턴은 거의 전방향 특성을 보였고 최대 이득은 약 2.0dBi이다.

• 한국전자파학회:학술대회논문집
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• 한국전자파학회 2005년도 종합학술발표회 논문집 Vol.15 No.1
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• pp.101-106
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• 2005

This paper presents a new microwave oscillator incorporating a corrugated coplanar waveguide (CCPW) electromagnetic bandgap (EBG) structure as its terminating resonance component. The use of a compact CCPW EBG structure was effective in reducing the phase noise and improving the harmonic characteristics of the microwave oscillator circuit without additional backside processing and drastic size increment. The fully planar CCPW oscillator oscillating at the frequency of 5.41 GHz showed a phase noise characteristic of -90.7 dBc/Hz at 100kHz offset and a second harmonic suppression of 42.67 dB.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2009년도 춘계학술대회 논문집
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• pp.49-51
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• 2009

Photonic crystal is a dielectric materials or a set of different dielectric materials with periodic structure of refractive index. Line defect obtained by leaving out a row of rod along the $\Gamma$-X direction. We showed the change of group velocity in waveguide mode and found a small group velocity. Characteristic of the small group velocity described by electric field distribution. As the phase variation, small group velocity confirmed from positive to negative.

• Journal of information and communication convergence engineering
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• 제14권3호
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• pp.184-190
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• 2016

We present experimental demonstrations of electromagnetic bandgap (EBG) structures for the wideband suppression of radiated emissions from a power bus in high-speed printed circuit boards (PCBs). In most of the PCB designs, a parallel plate waveguide (PPW) structure is employed for a power bus. This structure significantly produces the wideband-radiated emissions resulting from parallel plate modes. To suppress the parallel plate modes in the wideband frequency range, the power buses based on the electromagnetic bandgap structure with a defected ground structure (DGS) are presented. DGSs are applied to a metal plane that is connected to a rectangular EBG patch by using a via structure. The use of the DGS increases the characteristic impedance value of a unit cell, thereby substantially improving the suppression bandwidth of the radiated emissions. It is experimentally demonstrated that the DGS-EBG structure significantly mitigates the radiated emissions over the frequency range of 0.5 GHz to 2 GHz as compared to the PPW.

• ETRI Journal
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• 제33권1호
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• pp.13-17
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• 2011

A highly miniaturized on-chip $180^{\circ}$ hybrid employing periodic ground strip structure (PGSS) was realized on a silicon radio frequency integrated circuit. The PGSS was placed at the interface between $SiO_2$ film and silicon substrate, and it was electrically connected to top-side ground planes through the contacts. Owing to the short wavelength characteristic of the transmission line employing the PGSS, the on-chip $180^{\circ}$ hybrid was highly miniaturized. Concretely, the on-chip $180^{\circ}$ hybrid exhibited good radio frequency performances from 37 GHz to 55 GHz, and it was 0.325 $mm^2$, which is 19.3% of a conventional $180^{\circ}$ hybrid. The miniaturization technique proposed in this work can be also used in other fields including compound semiconducting devices, such as high electron mobility transistors, diamond field effect transistors, and light emitting diodes.

• Journal of the Optical Society of Korea
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• 제16권1호
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• pp.47-52
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• 2012

The use of a $Ti:LiNbO_3$ symmetric Mach-Zehnder interferometric intensity modulator with a push-pull lumped electrode and a plate-type probe antenna to measure an electric field strength is described. The modulator has a small device size of $46{\times}7{\times}1mm$ and operates at a wavelength of $1.3{\mu}m$. The output characteristic of the interferometer shows the modulation depth of 100% and 75%, and $V_{\pi}$ voltage of 6.6 V, and 6.6 V at the 200 Hz and 1 KHz, respectively. The minimum detectable electric field is ~1.84 V/m, ~3.28 V/m, and ~11.6 V/m, corresponding to a dynamic range of about ~22 dB, ~17 dB, and ~6 dB at frequencies of 500 KHz, 1 MHz and 5 MHz, respectively.

• ETRI Journal
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• 제28권4호
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• pp.529-532
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• 2006

This letter describes a compact printed helical resonator and its application to a microwave oscillator circuit implemented in coplanar waveguide (CPW) technology. The high quality (Q)-factor and spurious-free characteristic of the resonator contribute to the phase noise reduction and the harmonic suppression of the resulting oscillator circuit, respectively. The designed resonator showed a loaded Q-factor of 180 in a chip area of only 40% of the corresponding miniaturized hairpin resonator without any spurious resonances. The fully planar oscillator incorporated with this resonator showed an additional phase noise reduction of 10.5 dB at a 1 MHz offset and a second harmonic suppression enhancement of 6 dB when compared to those of a conventional CPW oscillator without the planar helical resonator structure.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 1998년도 하계종합학술대회논문집
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• pp.469-472
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• 1998

InGaAsP/InP ridge waveguide(RWG) distributed feedback(DFB) lasers (LD) operating at 1.55.mu.m were fabricated by a two step MOCVD process. The CW laser threshold and the slope efficiency from these lasers are 22.5mA and 0.127mW/MA perfacet at room temperature. Single longitudinal mode operation with side mode suppression of more than 30dB is obtained at 5mW. The temperature sensitivity and characteristic temperature (T$_{0}$) from DFB lasers were obtained 1.0.angs./.deg. C and 50.3K between 20.deg. C and 70.deg. C, respectively.y.

• Journal of information and communication convergence engineering
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• 제15권4호
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• pp.237-243
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• 2017

This paper presents an analysis of the electromagnetic interference of a heterogeneous power bus where electromagnetic bandgap (EBG) cells are irregularly arranged. To mitigate electrical-noise coupling between high-speed circuits, the EBG structure is placed between parallel plate waveguide (PPW)-based power buses on which the noise source and victim circuits are mounted. We examine a noise suppression characteristic of the heterogeneous power bus in terms of scattering parameters. The characteristics of the dispersion and scattering parameters are compared in the sensitivity analysis of the EBG structure. Electric field distributions at significant frequencies are thoroughly examined using electromagnetic simulation based on a finite element method (FEM). The noise suppression characteristics of the heterogeneous power bus are demonstrated experimentally. The heterogeneous power bus achieves significant reduction of electrical-noise coupling compared to the homogeneous power buses that are adopted in conventional high-speed circuit design. In addition, the measurements show good agreement with the FEM simulation results.