• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.26 no.11
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• pp.960-965
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• 2015

In this paper, a coupled line directional coupler using an LUC(Low-pass filter Unit Cell) of artificial transmission line is presented. The conventional coupled line coupler is limited in length by the ${\lambda}/4$ transmission line while the proposed coupling structure is implemented smaller than $90^{\circ}$ by inserting the phase delay line between two coupled line, reduced in physical size by configuring a phase delay line with an LUC having the characteristics of a typical transmission line in a particular frequency. A coupler having -10 dB coupling factor at the center frequency of 700 MHz is designed, fabricated. The measured result agrees well with that of conventional one. The length of the fabricated coupled line coupler has about 45 % in length compared to the conventional one.

• Journal of electromagnetic engineering and science
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• v.12 no.4
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• pp.280-286
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• 2012

The conventionally classified waves are reclassified in this paper, including the waves associated with metamaterial (MTM) transmission lines. Various types of guided waves in periodic structures are analyzed for 1D Composite Right/Left Handed (CRLH) transmission lines (TL). In addition, dispersion diagrams for 1D CRLH, RH, and LH TLs are presented in terms of radiation conditions. We have refined the design equations of the conventional 1D CRLH TL and proposed a condition to realize the desired phase shift and its slope per unit cell. This condition has been applied to the conventional Wilkinson power divider and realized into MTM added $90^{\circ}$ hybrid coupler. Based on the 10 dB return loss and the $90{\pm}10^{\circ}$ phase shift, the bandwidths of the MTM added $90^{\circ}$ hybrid coupler are 82.25% and 103.5% against the conventional 23% and 52.5%, respectively.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.14 no.2
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• pp.104-110
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• 2003

This paper proposed a simple 180$^{\circ}$ MMIC phase shifter for wideband application. The phase shifter simply consists of a Lange coupler and two GaAs PIN diodes. The measured performance of the phase shifter in the 2 to 6 GHz band shows a maximum phase error of less than 13$^{\circ}$, maximum 3.2 dB insertion loss, and minimum 6.3 dB return loss.

• Proceedings of the KIEE Conference
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• 2002.07c
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• pp.1919-1921
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• 2002

In this paper, we were designed the ferroelectric phase shifter using 3-dB, $90^{\circ}$ branch-line hybrid coupler with two ports terminated in symmetric phase-controllable reflective networks. The design of phase shifter is based on reflection theory of terminating circuits. In order to find the optimum conditions of reflect phase, the effect of a change of capacitance and transmission line connected with two coupled ports of a coupler have been investigated. To obtain more accurate design parameters, finite element method is applied. We were showed large phase variation with small capacitance variation in the parallel connection of capacitor and transmission line by using EM-simulation and circuit-simulation.

• Proceedings of the Korean Institute of Communication Sciences Conference
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• 1986.10a
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• pp.20-22
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• 1986

This paper represents a graphical design technique of the symmetrical dielectric waveguids couplers. Once the phase constants are given by a approzimate model analysis, coupling lengths are easily calculated for each coupler. These method give some new insight of the codirectional couplers.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.12 no.4
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• pp.513-520
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• 2001

In this paper, the directional coupler using three layer microstrip substrate is proposed and the design method is notified. Modified re-entrant mode coupler is the proposed structure that one layer is added on upper plane of coupled transmission lines and the floating conductor is placed on added layer's upper planes. This structure has high coupling for the increase of odd mode capacitance and also has good performance in VSWR, isolation, phase difference because the difference of effective permittivity is small in each mode. We have designed the coupler from the calculation of impedance, effective permittivity, coupling coefficient using even, odd mode analysis method. From the simulation and measurement, proposed coupler has about 2 dB more tighter coupling than conventional coupler and also has good performance in VSWR, isolation, phase difference.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.11 no.4
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• pp.575-581
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• 2000

In this paper, a new active phase shifter is proposed using a vector sum method, and a unique digital phase control method of the circuit is suggested. The proposed scheme was designed and implemented using a Wilkinson power combiner/divider, a branch line 3 dB quadrature hybrid coupler and variable gain amplifiers (VGAs) using gate FETs(DGFETs). Furthermore, it was also shown that the proposed scheme is more efficient and works properly with the digital phase control method.

• Journal of the Optical Society of Korea
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• v.3 no.2
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• pp.64-68
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• 1999

The performance of a fiber Bragg grating strain sensor constructed with 3$\times$3 coupler is investigated. A 3$\times$3 coupler Mach-Zehnder (M/Z) interferometer is used as wavelength discriminator, interrogating strain-induced Bragg wavelength shifts. Two quadrature-phase-shifted intensities are synthesized from the as-coupled interferometer outputs, and digital arctangent demodulation and phase unwrapping algorithm are applied to extract the phase information proportional to strain. Due to the linear relation between the input strain and the output of quadrature signal processing, signal-fading problems eliminated. In the experiment, a fiber grating that was surface adhered on an aluminum beam was strained in different ways, and the photodetector signals were transferred and processed in a computer-controlled processing unit. A phase recovery fo 7.8$\pi$ pk-pk excursion, which corresponds to ~650$\mu$strain pk-pk of applied strain, was demonstrated. The sensor system was stable over the environmental intensi쇼 perturbations because of the self-referencing effect in the demodulation process.

• Journal of the Institute of Electronics and Information Engineers
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• v.50 no.2
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• pp.54-59
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• 2013

This letter presents a shorted-stub tapped branch-line coupler for dual-band applications. In the new design, a shorted stub is used to realize 90 phase change at two frequencies. Closed-form design equations are derived to find the characteristic impedance and electrical length of the proposed branch lines using the ABCD-matrix. To verify the design concept, a microstrip coupler operating at 0.8 and 1.85 GHz is fabricated and measured.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.14 no.7
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• pp.734-740
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• 2003

In this paper, A Vector Modulator based a wideband analog phase shifter is realized with four P-I-N diode attenuators, an asymmetric coupled line coupler, a symmetric coupled line coupler, and a power combiner. Simple configuration to have advantages in cost, size, power, and the number of passive circuits is presented. The phase variation due to phase and amplitude error of a P-I-N diode attenuator is derived and used to optimize the overall circuit. The phase shifter shows a total phase shift of 360$^{\circ}$, a 8.2$^{\circ}$maximum phase error, and a 16${\pm}$2.5 dB insertion loss over the wide frequency range of 1 GHz to 3 GHz.