• Journal of information and communication convergence engineering
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• v.6 no.1
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• pp.55-58
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• 2008

In this paper, the new type wiggly directional coupler which uses the fractal coupled shape in coupled sections is presented. A commercial software has been used to analyze this new structure and the simulation results are compared to those of the conventional wiggly directional coupler. To verify the simulation results, the new type wiggly directional coupler was fabricated with the center frequency of 15GHz. The measurement results shows that the coupling of new structure proposed in this paper is more than that of conventional wiggly coupler. The results in this paper also show that the fractal shape coupled lines in wiggling sections can improve the coupling characteristics in wiggly directional coupler.

• The Journal of the Korea institute of electronic communication sciences
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• v.12 no.3
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• pp.445-450
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• 2017

In this paper, the directional coupler with half-power division is designed and fabricated by using the vertical coupling structure based on the CPW transmission-line. Even-mode and odd-mode of the vertical coupling structure can be analyzed by the conventional CPW-line and the CBCPW-line, respectively, with half thickness of the substrate. The directional coupler is designed by using the tefron substrate with the dielectric constant of 2.55 and the thickness of 0.76mm. Manufactured directional coupler has the center frequency of 2.45 GHz and the bandwidth of 66.1%. Also, the return loss and isolation are 19.52dB and 19.47dB, respectively, at the center frequency.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.07a
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• pp.344-347
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• 2000

We analyze the variation of coupling length as a function of the waveguide width for a directional coupler. It is interesting that the coupling length is not monotonic function of waveguide width for a given distance between the centers. The waveguide width for a maximum coupling length can be utilized for the optimum design of a directional coupler.

• Electrical & Electronic Materials
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• v.8 no.4
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• pp.443-450
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• 1995

A directional coupler which on the X-cut $LiNbO_3$ substrate is fabricated by using proton exchange method and self-aligned method. After proton exchange process, the waveguide is formed by annealing process. The relation ship between refractive index change of waveguide and maximum output was studied along with the annealing time. A self-aligned method was used to simplify the fabrication process of the waveguide and to maximize the efficiency of electric field. The on-off state of modulator has been observered with the switching of the directional coupler by the electric field effect and also the switching voltage of the directional coupler has been measured with 8.0 [V].

• ETRI Journal
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• v.27 no.6
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• pp.697-707
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• 2005

This paper proposes a new design of directional couplers with high directivity for personal communication services (PCS) and International Mobile Telecommunications-2000 (IMT-2000). The directional coupler is used to check and verify the power, frequency, and antenna reflection of a signal at transmission stations for mobile communications. The performance requirements of directional couplers are a strong coupling to reduce the effect on the transmitted power and high directivity to suppress the interference of the reflected signals and reduce the errors in communication. So far, various architectures have been proposed to gain high directivity, and there have been many studies used to obtain a strong coupling. However, conventional architectures for high directivity and strong coupling have a directivity of only about 20 dB, and there have been difficulties to achieve the higher directivity of 30 dB suitable for PCS and IMT-2000. This paper proposes a new architecture of directional couplers based on a grounding composed of strip lines, and compares the test results of this directional coupler with conventional ones. The results show that the proposed directional coupler has a directivity of more than 30 dB and is adequate for PCS and IMT-2000.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.10A
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• pp.1215-1222
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• 2004

In this paper, we proposed the directional coupler using two layer microstrip substrate which is improved coupling and isolation. Modified two-layer directional coupler is the structure which is added to the one-layer on the signal line and located the floating conductor on the added layer. Also, we applied the aperture on the ground plane in order to enhancing the coupling value, and located the conductor in order to enhancing the isolation and VSWR according to S$_{11}$. As a result, proposed two-layer directional coupler has about 2 dB more higher coupling and 20 dB more higher isolation than conventional couplerer

• Korean Journal of Optics and Photonics
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• v.14 no.4
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• pp.359-364
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• 2003

We propose a novel vertical directional coupler with polarization independent very short coupling lengths using the double-sided deep-ridge waveguide structure which could be implemented using double-sided process to polarization insensitive deep-ridge waveguide structures and investigate the effect of various structure parameters on the coupling length. Variation of coupling length for the variation of the waveguide width is smaller than that for the variation of the core thickness. Coupling length decreases as the inner cladding layer thickness and the core thickness decrease. The waveguide width with the polarization independent coupling length decreases as the inner cladding layer thickness decreases for the same core thickness and the core thickness decreases for the same inner cladding layer thickness.

• Korean Journal of Optics and Photonics
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• v.15 no.4
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• pp.293-298
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• 2004

We investigate the effect of the wing width and thickness of a Double-Sided Deep-Ridge(DSDR) vertical directional coupler on the coupling length dependent on the polarization, We have found that the DSDR vertical directional coupler without a wing does not have polarization independent coupling lengths. The variation of the coupling length of TE and TM modes and the difference between the coupling lengths of the two modes are negligible as the wing width increases beyond the specific wing width for the same wing thickness. Thus, we can see that a DSDR vertical directional coupler has a wing width larger than the minimum wing width to obtain the polarization independent coupling length. The minimum wing width increases as the wing thickness increases for the same core thickness and as the core thickness decreases for the same wing width. Also, we have found that the minimum wing thickness is determined by the core thickness and the minimum wing thickness decreases as the core thickness increases.

• 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.

• Journal of the Optical Society of Korea
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• v.9 no.3
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• pp.99-102
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• 2005

Directional couplers of gradient-index plastic optical fibers were fabricated and characterized. In particular, we have employed a core-facet technique to make the directional couplers, which require mechanical side polishing and linkage. We have measured insertion loss, excess loss, and coupling ratio of the fabricated couplers as a function of polishing depth and coupling length. We found that polishing depth of $\~300{\mu}m$ and coupling length of $\~35mm$ are optimum conditions for minimizing the insertion and excess losses and for achieving 1: 1 coupling ratio.