• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.26 no.2
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• pp.158-164
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• 2015

The main mission of OTM(On-The-Move) satellite communication system is to provide satellite communication service while moving on a vehicle. So it should have a capability to maintain a reliable communication channel when it travels at high speeds or in a severe fluctuation region. This paper presents a small-sized multi-mode monopulse structure applicable to OTM satellite communication system which has only single mode-coupler with a pair of slot using a feature of circular polarized received signal. And tracking error signal is defined using fundamental and high-order modes.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.13 no.2
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• pp.227-232
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• 2009

The simple PSK signal generation method using a quadrature hybrid coupler and reflection coefficient elements was analyzed in this paper. The PSK modulation signal with a constant constellation is generated by reflection coefficient from 90o hybrid coupler output ports, the high-mode PSK signal is also generated by the hybrid structure of coupler, delay line and power combiner. The BPSK signal is simply generated by a 90o hybrid coupler and reflection elements, and QPSK with 90o phase constellation is generated by additional delay line and power combiner. By simulation results, the generated PSK signals by the proposed circuit get good modulation spectra within 3o phase error.

• 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.

• 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

• 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 IEEK Conference
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• 2003.11c
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• pp.357-360
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• 2003

In this paper, we investigated the characteristics of 4${\times}$4 thermo-optic switch using two mode interference(TMI) coupler. We designed this matrix switch by using a configuration which combines a double Mach- Zehnder interferometer(MZI) switching unit. The average extinction ratio and average excess loss of the 4${\times}$4 thermo-optic switch was 33.7dB, 0.29dB, respectively.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.23 no.5
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• pp.145-150
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• 2023

Non-uniform optical taper waveguides have been widely used as devices for high-efficiency mode coupling, as they are integrated with single-mode optical fibers or photonic crystal waveguides. In this paper, we present a new platform for chemical sensing and bio-sensing using optical taper waveguides with these characteristics. The principle of operation is based on the coupling efficiency and interference properties of optical directional coupler (DC) and multi-mode interference coupler (MMIC). First, the curvature characteristics of taper sections of DC and MMIC is explained, and the design specifications of optimized taper waveguide to increase waveguide sensitivity is selected. Next, the sensor response to the change in refractive index of sensing analyte is numerically analyzed. Numerical results show that as the length of couplers increases, the effective index per change in refractive index unit (RIU) of analyte increases, and that sensitivity can be tuned using taper DC and MMIC design techniques.

• 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.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2002.11a
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• pp.157-160
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• 2002

In this paper, a novel lumped equivalent circuit for a conventional parallel directional coupler is proposed. The equivalent circuit and design formula for the presented lumped element coupler is derived based on the even-and odd-mode properties of a parallel-coupled line. By using the derived design formula, we have designed the 3㏈ and 10㏈ lumped element directional couplers at the center frequency of 100Mhz. Furthermore, a chip type directional coupler has been designed to fabricate with multilayer configurations by employing the Low Temperature CofiredCeramic (LTCC) process. Designed chip-type directional coupler has a 10㏈-coupling value at the center frequency of 2㎓. Excellent agreements between simulations and measurements on the designed directional couplers show the validity of this paper

• Journal of Advanced Marine Engineering and Technology
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• v.38 no.8
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• pp.995-999
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• 2014

In this paper, a new size-reduction approach for branch-line coupler is introduced which uses parallel end-shorted coupled lines with lumped capacitors. The characteristic of the new design was analyzed using even-odd mode method, and simulated on HFSS before fabricated on the FR4 epoxy glass cloth copper-clad plat (CCL) PCB substrate at center frequency of 1 GHz. The electrical length of transmission line was reduced to 15 degrees, therefore the size of branch-line coupler was largely reduced approximately maintaining the same characteristic around the stable center frequency. The insertion loss of the branch-line coupler filter was -4.39 dB. The size of the overall hybrid is $20mm{\times}20mm$. Measurements results were well agreed with the simulated ones.