• Journal of Advanced Marine Engineering and Technology
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• v.32 no.1
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• pp.147-152
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• 2008

This paper has been fabricated the two different type of variable attenuators using a characteristics of a 3 dB directional coupler and pin diodes. One was not analyzed using the conventional even-odd modes but used simple two-port techniques. The resulting scattering parameters described operation characteristics for the general case where the terminating impedances are equal and unequal. After analyzing resistor role of the ${\pi}$ type fixed attenuator. this paper used a pin diode instead of a resistor. The variable attenuators were fabricated using pin diodes for current-controlled attenuation on the coupled ports of a 3 dB branch-line coupler and ${\pi}$ type fixed attenuator. The realized variable attenuators have more than 33 dB attenuation ranges at 2.1 GHz. and the input and output reflection coefficients are less than -13 dB. These results could be applied to mobile communication systems. It can be varied gain of the power amplifier according to change a outdoor environmental temperature and improved linearity.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.23 no.7
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• pp.768-773
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• 2012

A branch-line hybrid using microstrip artificial transmission lines(ATLs) with slotted-triangular patches is proposed. The proposed artificial transmission line is compact in structure as well as easy to adjust the characteristic impedance and electrical length of equivalent transmission line by changing the slot's parameters; hence, it is useful for miniaturizing conventional transmission lines. The designed branch-line hybrid, because of the use of the right angled isosceles triangular shaped artificial transmission lines as building blocks, has no useless empty space, and hence optimally miniaturized. A fabricated 3 dB branch-line hybrid shows the coupling variation of ${\pm}0.5$ dB and the phase difference between two output ports of $91^{\circ}{\pm}4^{\circ}$ within 15 % bandwidth at 2.45 GHz center frequency. The size of proposed branch-line hybrid is only 38% of the conventional branch-line hybrid.

• 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.

• Journal of Advanced Navigation Technology
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• v.14 no.6
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• pp.909-915
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• 2010

In this paper, the unequal power divider based on CRLH (Composite Right/Left-Handed) transmission line with dual-band characteristic is proposed. They consist of dual-band branch line hybrid coupler, the connection between input and isolation port of hybrid coupler and ${\lambda}/4$ impedance transformer. When the transmission line between input and isolation port of hybrid coupler is asymmetrical connected, the divider is obtained the output results of the equal phase and unequal power dividing ratio. The simulation results of the divider represent the power ratio of 0 dB ~ 20 dB. To validate a function of divider, the hybrid coupler and transformer with 880 MHz and 1850 MHz is implemented. As a result, the proposed unequal divider obtains the power ratio of 3.2 dB ~ 8.8 dB at 880 MHz and 2.5 dB ~ 14.0 dB at 1850 MHz.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.8 no.5
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• pp.1076-1081
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• 2007

In this paper, we propose a new switch structure for time division duplex(TDD) system. The existing TDD structure utilizes a circulator fur isolation characteristic between ports. However, the circulator produces intermodulation distortion signals which are undesired signal because of its nonlinear properties. The proposed circuit is composed of a modified branch-line hybrid coupler which controls the signal flow while the isolated port is open-/short- terminated. In order to prove the validity of the presented structure, the switch circuit is fabricated and measured at 2.3GHz, the center frequency of Wibro service system.

• Proceedings of the IEEK Conference
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• 2005.11a
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• pp.925-928
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• 2005

In this study, we fabricated the DAMLs using surface micromachining technology as well a low loss coupler for the millimeter-wave band applications using these DAMLs. The structure of DAML is that a signal line is supported on ground plane by dielectric posts. Therefore it has advantages about the loss characteristic and the stable structure. The other advantage of the DAML process is a simple and convenient technique using 4 mask steps, even if it has a micromachining technology. The lowest loss of the fabricated DAML was obtained 2.2 dB/cm at 110 GHz. To obtain the low loss characteristic, couplers were designed and fabricated by using DAMLs. The fabricated ring hybrid coupler has the coupling of 3.58 dB and the thru of 3.31 dB at 60 GHz. We can also obtain the coupling of 3.42 dB, the thru of 3.82 dB from fabricated branch line coupler at 60 GHz.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.48 no.6
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• pp.489-493
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• 1999

In this paper, an analysis of microstrip-slotline transition is performed using a 3D vector Finite Element Method(FEM). Artificial anistropic absorber technique is employed to implement an matching boundary condition in FEM. On the base of the analysis, power divider/combiner is designed. The structure of the power combiner already developed are Branch-line coupler, Rat-race coupler, Wilkinson coupler, Lange coupler, etc. Which are all planar, If the frequency goes up, the coupling efficiency of these planar couplers is decreased on account of skin loss. Especially, in millimeter-wave band, the efficiency of more than two ways combiner is radically reduced, so that application in power amplifier circuit is almost impossible, Microstrip-slotline transition structure is a power combining technique integrated into wave-guide, so that the loss is small and the efficiency is high. Theoretically, we can mount several transistors into the power-combiner. This makes it possible to develop a high power amplifier. The numerically calculated performances of the device that is, we believe, the best are compared to the experimental results in Ka-Band(26.5GHz-40GHz).

• International Journal of Internet, Broadcasting and Communication
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• v.10 no.3
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• pp.109-114
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• 2018

In order to improve performance for the size of the BLPD, the CCL is used for the realization as the delay line. As realizing lower coupling coefficient and lower characteristic impedance, the CCL has good performance of the phase delay. The CCL is applied as the compact BLPD with optimized coupling factor and matched impedance because the lower coupling coefficient and lower characteristic impedance are increased the size and the loss, respectively. Designed BLPD using the CCL has the size of $0.13{\lambda}_g{\times}0.13{\lambda}_g$ and the size-reduction ratio of fabricated BLPD using the CCL has 58.5% ($21.08{\times}21.40mm^2$). Also, fabricated BLPD is measured the insertion loss of 3.16dB at the center frequency of 1.78GHz and the 20dB bandwidth is 9.58%. Differenced magnitude and phase between threw port and coupled port are measured 0.1dB and $89.9^{\circ}$, respectively. These performances are almost same compared with the conventional BLPD. Suggested application of the CCL can be used various devices and circuits for the size-reduction.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.11 no.8
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• pp.1297-1304
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• 2000

The full wave method requires a great number of computer memory and lasting long CPU time for the calculation of the discontinuity problems in microstrip structures. While the computation only for the transverse field components at those structures causes the both of time and memory reduction. For the case of the calculating only transverse components for the most of microstrip structures such as low-pass filter, branch coupler and patch antenna the computer memory and running time can be reduced to about 50% and 33%, comparing to the full wave computation. Consequently, the proposed method than that of TEM-mode has an advantages of higher speed and less memory than that of conventional FDTD analysis.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.20 no.2
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• pp.253-259
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• 2016

This paper introduces a new variable power divider circuit with an arbitrary power division ratio ranging from $1:{\infty}$ to ${\infty}:1$. The proposed power divider circuit consists of one branch-line coupler to be a good input matching characteristic, two variable phase shifters with 90-degree phase variation to be connected two output paths of the branch-line coupler, and one ring-hybrid coupler to combine output signals of two variable phase shifter. The power division ratio between the two output ports of the proposed power divider can be easily controlled by the phase variation of the two phase shifter. The proposed power divider circuit fabricates on laminated RF-35 (h = 20 mil, er=3.5; Taconic) with a center frequency of 2 GHz. The power division ratio of the fabricated prototype varies from about 1:1000 to 5000000:1, with an input reflection characteristic(S11) of below -20 dB, an insertion loss of about -1.0 dB, and an isolation characteristic of below -17 dB between two output ports in the range 1.9-2.1 GHz.