• 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.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.44 no.9
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• pp.63-69
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• 2007

The directivity of crossed waveguide directional coupler is generally decreased according as coupling coefficient of it increase. In this paper, the geomertical parameters of crossed slot pair for directivity improvement is modified and the formulas for design of it are proposed. The crossed waveguide directional coupler designed upon the formulas is fabricated with the WR42 waveguide in K-band. The measured results show that the coupling coefficient is 21.5 dB and directivity is minimum 23.9 dB over the operating frequency from 18GHz to 26.5GHz.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.4A
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• pp.320-327
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• 2005

In this paper, compensation structures are proposed in the CPW directional couplers with finite-extent backed conductor for tight coupling. The proposed structures are realized T-shaped expanded slots and modified finite-extent backed conductor in CPW coupled structure. The T-shaped expanded slots was used to avoide reduced coupling and modified finite extent backed conductor of dumbbell shape was used to enhance directivity and matching. The designed CPW directional couplers at 1 GHz has good directivity without reducing coupling in simulation by EM solver based on full-wave analysis and measurements.

• KIEE International Transactions on Electrophysics and Applications
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• v.11C no.4
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• pp.150-154
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• 2001

In this paper, we presented a novel structure of microstrip directional coupler for realizing the high directivity characteristic and tight coupling. The achievement of the high directivity with microstrip configuration was carried out by matching the even and odd mode effective phase velocities. By using 2-dimensional finite element (FE) calculations, the phase velocity for each mode and design parameters were extracted for given dimensions. Based on the extracted design parameter with phase-matched condition, we designed and fabricated 3dB and 4.7dB directional coupler at 2.0GHz. Experimental results of microstrip coupler show good performance with excellent isolation characteristics.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.19 no.5
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• pp.175-180
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• 2019

The optical characteristics and power transfers between guiding channels of blazed grating-assisted directional coupler (B-GADC) are evaluated in detail by using novel and rigorous modal transmission-line theory (MTLT) based on eigenvalue problem. To evaluate the coupling efficiency of B-GADC, the dispersion curves as a function of the grating period and wavelength are analyzed numerically for quasi-TE and quasi-TM modes. Furthermore, symmetric, sawtooth and asymmetric grating profiles are considered to know the effect of blazing characteristics on power transfer of GADC. The numerical results show that the grating period for minimum-gap condition to obtain maximum power transfer decreases gradually as the blazed structure changes from symmetric to asymmetric profile. On the other hand, the coupling length increases reversely.

• Journal of the Korean Institute of Telematics and Electronics
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• v.12 no.6
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• pp.14-20
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• 1975

Characteristics of coupled trigonometric transmission lines (CTTL) are studies based on the theory of general coupled nonuniform transmission lines. First, the 4-port transmission matrix parameters of networks and directional couplers using CTTL. The phase slrift characteristic of the all-pass networks and the magnitude characteristic of the directional couplers are studied in detail for various coupling and a high-pass small ripple directional coupler using CTTL are given and their physical realization is considered.

• Proceedings of the IEEK Conference
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• 2005.11a
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• pp.627-630
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• 2005

Novel unified criterion to optimize power coupling at optical directional couplers with discontinuous input/output interfaces is first defined and evaluated numerically. The numerical results reveal that maximum power transfer between guiding slabs without discontinuous interfaces is dominated by conventional phase-matching condition while the guiding structures with discontinuous interfaces has maximum power transfer at an equi-partition condition, which describes the power distribution condition between two rigorous modes propagating through optical couplers.

• Journal of the Optical Society of Korea
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• v.8 no.4
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• pp.149-155
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• 2004

Newly developed modal transmission-line theory(MTLT) is used to analyze rigorously the optical power distribution in grating-assisted directional couplers(GADCs) with three guiding channels. By defining a novel coupling efficiency ${\eta}$ amenable to the rigorous analytical solutions of modal transmission-line theory, we explicitly evaluate the power coupling and distribution of TM modes. The results reveal that the incident power is sensitively partitioned through three output channels in terms of such grating parameters as the grating period, the duty cycle, and the operating wavelength.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2004.11a
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• pp.751-754
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• 2004

This paper presents a design of the directional radiation pattern by using the structural-acoustic interaction. For this purpose, prediction of the pressure distribution of the field points and radiation pattern of the structural-acoustic coupling system is shown. In order to get a strong coupling, coupled system that has a finite space and a semi-infinite space separated by two flexible walls and an opening is selected. A volume interaction can be occurred in structure boundary and a pressure interaction can be happened in the opening boundary. The coupled system is maximized the radiation power on the main axis and minimized the side lobe level.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.14 no.10
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• pp.1052-1059
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• 2003

In this paper, we proposed the directional coupler using two layer microstrip substrate which is improved coupling and isolation. Also, we notified a design method. Modified re-entrant mode coupler is the structure added to the aperture on the ground plane in order to improving the coupling value. And, by adding to slits on the floating conductor, this structure has good performance in isolation, VSWR according to S$\sub$11/, and phase difference. As a result, proposed re-entrant mode microstrip directional coupler has about 1.5 dB more higher coupling and 20 dB more higher isolation than conventional coupler. And because this coupler has good performance in phase difference, it can be used multi-section coupler.