• 한국정보통신학회:학술대회논문집
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• 한국정보통신학회 2015년도 추계학술대회
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• pp.68-70
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• 2015

4단자 커플러 회로는 입력 단자, 격리 단자와 두 개의 출력 단자로 구성된다. 입력 단자와 격리단자에 신호가 입력하면 입력하는 신호의 세기 및 위상 특성에 의해 두 개의 출력 단자의 출력 신호의 세기와 위상이 결정된다. 본 논문에서는 대표적인 4단자 커플러 회로인 브랜치라인 하이브리드 커플러와 링-하이브리드 커플러를 이용하여 두 개의 입력 단자의 입력 신호 특성에 따른 출력 신호 특성을 분석하였다. 또한, 분석한 신호를 바탕으로 브랜치라인 커플러와 링-하이브리드 커플러의 새로운 이용 방법에 대해 살펴 보았다.

• 한국정보통신설비학회:학술대회논문집
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• 한국정보통신설비학회 2006년도 하계학술대회
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• pp.197-201
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• 2006

Folded lines are applied to design a compact microstrip ring hybrid. Using the proposed structure we achieve both significant size reduction and good harmonic suppression with the same results of conventional ring hybrid at 2.41GHz. Including the third harmonic frequency, up to 11GHz band harmonics are suppressed to -20dB. The size of the proposed ring-hybrid is reduced to one forth of the conventional ring hybrid. The measured frequency responses agree well with simulated ones.

• 한국정보통신학회논문지
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• 제9권7호
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• pp.1534-1540
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• 2005

직접 변환 방식은 혼합기를 사용하는 구조와 6-단자 회로를 사용하는 구조를 갖는다. 6-단자 회로를 사용하는 방식은 혼합기를 이용하는 방식보다 회로 구조가 간단하고 집적화도 쉬운 장점을 가지고 있다. 그리고 다이오드 작동을 위한 전압이 혼합기를 작동시키기 위한 전압보다 낮은 장점을 가지고 있으며 LO에서의 소비전력이 낮고 광대역으로 구현하기 유리한 점을 보이고 있다. 본 논문에서는 branch-line 결합기로 구성되는 6-단자 회로와 ring hybrid 결합기로 구성되는 6-단자 회로를 설계하고 성능을 비교 분석하였다.

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2005년도 추계종합학술대회
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• pp.481-484
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• 2005

직접 변환 방식은 혼합기를 사용하는 구조와 6-단자 회로를 사용하는 구조를 갖는다. 6-단자 회로를 사용하는 방식은 혼합기를 이용하는 방식보다 회로 구조가 간단하고 집적화도 쉬운 장점을 가지고 있다. 그리고 다이오드 작동을 위한 전압이 혼합기를 작동시키기 위한 전압보다 낮은 장점을 가지고 있으며 LO에서의 소비전력이 낮고 광대역으로 구현하기 유리한 점을 보이고 있다. 본 논문에서는 branch-line 결합기로 구성되는 6-단자 회로와 ring hybrid 결합기로 구성되는 6-단자 회로를 설계하고 성능을 비교분석하였다.

• Journal of electromagnetic engineering and science
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• 제17권2호
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• pp.65-70
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• 2017

The design and implementation aspects of a new single-balanced mixer for ultra-wideband (UWB) applications are presented in this study. The proposed mixer utilizes a miniaturized UWB ring coupler as a balun, consisting of a pair of in-phase and inverted-phase transitional structures. The well-balanced UWB performance of the ring coupler, aside from the optimized diode matching, results in improved conversion loss and inter-port isolations for a wide bandwidth. The size of the implemented single-balanced diode mixer is reduced to about 60% of the area of the conventional single-balanced ring diode mixer. The measured results of the proposed mixer exhibit an average conversion loss of 7.5 dB (minimum 6.7 dB) and a port-to-port isolation of greater than 18 dB over a UWB frequency range of 3.1-10.6 GHz. The measured results agree well with the simulated results.

• Journal of electromagnetic engineering and science
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• 제11권4호
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• pp.235-238
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• 2011

In this paper, a novel low phase noise voltage-controlled oscillator (VCO) using metamaterial structure and rat race coupler is presented for reducing the phase noise without the reduction of the frequency tuning range. The metamaterial structure has been realized by microstrip square open loop double split ring resonator (SRR). The rat race coupler shows slightly higher transmission compared to a Wilkinson combiner and is, therefore, used instead to improve the performances of VCO. By providing these unique modifications, the proposed push-push VCO has a phase noise of -126.30~-124.83 dBc/Hz at 100 kHz in the tuning range of 5.672~5.800 GHz.

• 전기학회논문지P
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• 제59권1호
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• pp.123-128
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• 2010

We have investigated the properties of the novel triangular ring resonator with the total internal reflection mirrors and the semiconductor optical amplifier for photonic integrated circuits (PIC). A novel triangular resonators containing active and passive sections are fabricated and characterized with various multimode interference (MMI) lengths. The optimum MMI length and width turn out to be 108 and 9 ${\mu}m$, respectively. A free spectral range of approximately 228 GHz is observed near 1558 nm along with an on-off ratio of 9 dB. The proposed triangular resonator has a good advantage to remove the direct coupling between the two access waveguides of the MMI coupler. Hence, such resonators can be directly integrated with other devices making compact and highly functional PIC possible.

• 한국소음진동공학회논문집
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• 제16권11호
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• pp.1172-1178
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• 2006

Measurement of blade strain with sensors directly installed on the blade has one critical issue, how to send the sensor signal to the ground. Strain-gauges have been dominantly used to directly measure stress of a blade and either a slip ring or a telemetry system has to be used to send measured signal to the ground. However, both systems have many inherent problems and sometimes very severe limitations to be practically used. In this paper, new on-line strain monitoring method using. FBG(Fiber Bragg Grating) sensors and a beam coupler is introduced. Measurement of rotor stress using FBG sensors is nothing new, but unlike other system which installs all necessary instruments on the rotor and use telemetry system to send data to the ground, this system makes use of light's unique characteristic - light travels through space. In this new approach, single optical fiber with many FBG sensors is installed on the blade and all other necessary instruments can be installed at ground thereby giving tremendous advantages over slip ring or telemetry system. A reference sensor is also introduced to compensate the beam coupler's transmission loss change due to rotation. The suggested system's good performance is demonstrated with experiments.

• 대한기계학회논문집A
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• 제32권1호
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• pp.77-82
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• 2008

Strain-gauges have been dominantly used to measure strain at various points on a rotor, however, either a slip ring or telemetry has to be used to send sensor signals to data acquisition instruments at stationary side. Both slip ring and telemetry have numerous inherent problems which force severe limitations in real applications. This paper introduces a new rotor condition monitoring system using FBG(Fiber Bragg Grating) sensors and a rotary optical coupler. A single optical fiber with many FBG sensors is installed on the rotor and an optical dynamic interrogator is installed at stationary side. The sensor signal connection between rotating part and stationary part is made by the rotary optical coupling method which makes use of light's unique characteristic-light travels through space. Broad band light source from the interrogator travels to the optical fiber on the rotor and reflected FBG sensor signals travel back to the optical fiber on stationary side and are connected to the interrogator. Rotary optical coupler's insertion loss change due to rotation is compensated by using a reference sensor installed at the center of the rotor. The proposed system's performance has been successfully demonstrated by accurately measuring strains at 5 points on a blade rotating at high speed.

• 한국광학회지
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• 제25권3호
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• pp.146-149
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• 2014

The homogeneous line broadening in EDF leads to unstable lasing and strong mode competition. In this paper a multiwavelength fiber ring laser that overcomes these effects by using variable attenuators between the DWDM and $1{\times}N$ coupler, has been proposed. Fiber ring lasers with four and eight wavelength outputs are implemented, and we show that the output powers can be adjusted with stable operation. The EDF ring laser has one four-wavelength output and four of single wavelengths, with OSNR of 50 and 60 dB respectively.