• KSCI Review
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• v.15 no.1
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• pp.11-16
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• 2007

본 논문에서는 X-Band용 두 개의 발진기를 사용하여 중간결합을 통한 위상잡음 특성을 개선할 목적으로 중간동기결합 구조의 발진기를 제안하였다. 제안된 구조는 각각의 발진기는 Hai-Pin을 이용한 발진기로 설계를 하였으며, 두 발진기가 중간결합을 위해 갖는 위상차는 발진기들의 바이어스를 이용하여 조정을 한다. 제안된 구조의 수치계산을 통한 설계, 하드웨어 구현 및 실험을 통해 측정된 결과를 제시하였으며, 측정 결과로 위상잡음 특성이 약 100dBc/Hz 개선됨을 보였다.

• Journal of the Korean Institute of Telematics and Electronics D
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• v.35D no.6
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• pp.54-62
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• 1998

The crosstalks of two-waveguide & three-waveguide directional couplers are analyzed. Advantages and disadvantages for each coupler are compared and discussed. Based on the relationship between the coupled mode and the normal mode, the mathematical expressions are derived in terms of the crosstalks for each directional coupler. Numerical techniques such as the finite-difference method and the beam propagation method are employed to testify the validity of the derived equations. The calculation results show that two-waveguide directional coupler is superior to any types of three-waveguide couplers from the practical viewpoint of the crosstalk and the coupling length.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.22 no.6
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• pp.598-604
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• 2011

A method of miniaturizing branch line coupler with connected coupled lines is presented. The quarter-wavelength transmission lines in the typical microstrip branch line coupler are replaced with the connected coupled lines with same characteristics of ones for compact size. The connected coupled line is analyzed by T-equivalent circuit and Z parameters based on the even-odd mode analysis. The proposed branch line couplers with connected coupled line are designed and fabricated on FR4 substrate at 2.4 GHz. The measured results show good agreement with theoretical prediction. And the experimental results show that the size of coupler is 37 precent smaller than conventional coupler. This minimized coupler is suitable for Butler Matrix as feeder for mobile communication beam forming antenna.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.17 no.1
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• pp.10-16
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• 2024

Microstrip directional couplers using microstrip lines do not have good directivity characteristics because the dielectric constant of the substrate is different from that of air. To solve this problem, a compensation capacitor is sometimes attached between the coupling lines to improve directivity. This paper proposes a directional coupler with high directivity using interdigital capacitors implemented with transmission lines instead of lumped capacitors. The directional coupler designed and fabricated using the proposed method showed a coupling factor of 20 dB and a directivity of higher than 30 dB at 2.14 GHz. This directional coupler can be used as two directional couplers because it has two coupling ports and two isolated ports.

• Proceedings of the Optical Society of Korea Conference
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• 2003.02a
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• pp.174-175
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• 2003

광섬유-평면도파로 결합기는 평면도파로의 재료와 구조에 따라 다양한 응응이 가능하다. 특히 평면도파로의 전기광학 효과를 이용하면 고속 광변조 현상을 얻을 수 있다. 평면도파롱에 전기장을 인가하기 위해서는 두개의 도체 전극이 필요하다. 전극으로 주로 금속을 많이 이용하기 때문에 금속층이 포함된 광섬유-평면도파로 결합기의 특성을 연구하는 것이 요구된다. 본 논문에서 그림 1과 같이 금속 중간층이 포함된 광섬유-평면도파로 결합기의 구조의 동작특성을 측정하고 결과를 보고한다. (중략)

• Proceedings of the Optical Society of Korea Conference
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• 2003.07a
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• pp.18-19
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• 2003

측면 연마 광섬유 결합기는 비록 제작 공정이 다소 복잡하지만 다양한 응용이 가능하기 때문에 많은 연구가 진행 되어 왔다. 특히 최근에는 광센서나 초고속 광통신망에 편광 유지 광섬유를 이용한 광학소자의 필요성이 증가 하고 있다. 본 논문은 얇은 중간 금속 층을 가지는 측면 연마 편광 유지 광섬유 결합기를 이용한 편광 분리기에 관한 실험 연구 결과를 보고한다. (중략)

• The Journal of Korean Institute of Communications and Information Sciences
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• v.28 no.8A
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• pp.626-632
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• 2003

In this paper, forward-wave -3㏈ directional coupler with finite-thickness conductor and asymmetrical coupled lines are designed and experimentally verified using mode-matching based design methodology. Most of studies published in the literatures about the coupled lines are mainly concentrated on the adjustment of coupling amount by changing various geometric configurations. The analysis results in this paper show that thicker metalization requires reduced coupler length in the forward-wave directional coupler composed of asymmetrical coupled lines. Several forward-wave directional -3 ㏈ couplers with finite metalization thickness composed of asymmetrical coupled microstrip lines have been designed in the 5 ㎓ based on proposed design method. The measured data show -4.05㏈∼-4.09㏈ coupling at center frequency which is very closed to design value. The tight coupling has been implemented with accurate design methodology which take mentalization thickness into account.

• Korean Journal of Optics and Photonics
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• v.19 no.1
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• pp.25-30
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• 2008

In this paper, a novel architecture for device miniaturization of multimode interference-based (MMI) couplers is proposed. The coupling length of $N{\times}N$ MMI couplers scales as the square of the MMI region width so that the use of these structures with large-N ports can require large chip size. To solve the design problem, the butterfly grating-assisted MMI couplers, that have smaller device dimensions than conventional MMI couplers, are discussed and evaluated. Numerical simulations and novel design rules for such structures derived through theoretical analysis are presented.

• Journal of the Korean Institute of Telematics and Electronics D
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• v.36D no.4
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• pp.1-7
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• 1999

The demands for the various type of directional coupler, which is for the sampling of the signal levels in mobile communication baseband or transceiver systems, are growing. The proposed dual directional coupler, which has three parallel coupled transmission lines, can provide the dual coupling and good isolation characteristics between the coupling ports. In this paper, the novel analysis method and the design equation of even and odd mode for the dual directional coupler, which is employing the asymmetrically coupled transmission lines, are proposed. Using the proposed method, the dual directional coupler for PCS system has been designed and fabricated. We obtained the desired coupling value and the high directivity of 40dB. Measured results show the validity of this design method.

• Proceedings of the KAIS Fall Conference
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• 2009.12a
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• pp.223-225
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• 2009

본 논문에서는 CRLH 전송 선로를 이용한 스터브 구조의 이중 대역 가지선로 결합기를 제안한다. 기존의 스터브 구조의 이중 대역 가지 선로 결합기는 동작하는 두 주파수가 근접할수록 스터브 선로의 임피던스가 증가해 구현이 불가능 하다. 제안된 이중 대역 가지선로 결합기는 비교적 근접한 1800MHz와 2300MHz 두 주파수에서 동작한다. 고 임피던스 스터브 선로는 이중 대역 소자 설계에 유용한 CRLH 전송 선로를 사용하여 구현 된다. 두 주파수에서 측정된 삽입 손실은 이상적인 결합기에 비해 최대 1.88dB의 오차가 났으며 두 출력 포트 사이의 위상차는 $1^{\circ}$미만 이다. 동작하는 두 주파수의 비는 1.28:1로 비교적 작은 차이를 보인다.