• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.20 no.1
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• pp.19-26
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• 2006

The ccrf-discharge has in comparison with the hollow-cathode discharge and DC-discharge some advantages: Simple design of the tube and homogeneous plasma. The ccrf-discharge was researched with the goal, to use on the excitation of the gas laser. In this work a rf-exciting system was planned and developed. With it a homogeneous discharge was produced in the cw operation. To supply the rf-power with the frequency 13.56[MHz] effectively in the discharge, laser tube were used with inner diameter of 5[mm] and the specially developed rf-electrodes. A matching circuit was composed also. Thereby the impedance of the discharge tube was adjusted to the 50[$\Omega$] output resistance of the rf-source.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.26 no.12B
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• pp.1724-1732
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• 2001

In this paper, a technique for increasing the bandwidth of microstrip array antennas using the parallel coupled lines on a single layer is presented. Four types of wideband microstrip array antenna are designed and the characteristics of each type are analyzed. In addition, an iterative method using a distributed network is proposed to design the parallel coupled lines as a wideband impedance matching network. Measurements show that the proposed antennas provide wider bandwidths ∼1.7 times those of conventional microstirp array antennas, while the sizes of proposed antennal are the same as that of a conventional array. And low cross-polarization level can be obtained through symmetrical locations of the parallel coupled lines section

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.9 no.3
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• pp.399-409
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• 1998

In this paper, the broad-band design theory for weakly-coupled Tap-Off for CATV systems has been described and the transmission line impedance matching method has been proposed. The fabricated weakly-coupled Tap-Offs based on the above theory and method have been much improved in the frequency characteristics compared with conventional ones. Thus, the useful bandwidth of weakly-coupled Tap-Offs have been extended from 5 to 2000 MHz. It is also recognized that turn numbers of the coils composing the transformer are not integers but 0.9, 1, 1.9, 2, 2.9, etc., in the actual circuits. Further, the practical measurements of the frequency characteristics for a fabricated weakly-coupled Tap-Off show very good agreements with theoretical results, and hence, the validity of the proposed design theory and transmission line impedance matching method have been confirmed.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2017.10a
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• pp.55-56
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• 2017

In this paper, a wideband loop antenna is designed using a CPW feeding method for indoor digital TV applications. The proposed loop antenna consists of a square loop and two circular sectors which connect the loop with central feed points, and the CPW feed line is inserted in the lower circular sector. The CPW feed line is designed to match with the 75 ohm port impedance for DTV applications, and the ground slots are etched in order to improve the impedance matching in the middle frequency region. The optimized antenna is fabricated on FR4 substrate, and the experiment results show that it operates in the frequency band of 463-1,280 MHz for a VSWR < 2, which assures the operation in the DTV band.

• Journal of Advanced Navigation Technology
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• v.26 no.1
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• pp.15-21
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• 2022

In this paper, we propose a method to implement an unequal power divider with different complex termination impedances for different output power ratios. The proposed method was designed using a matching the terminated complex impedances of the output port using only the transmission line, and presented an isolation circuits to satisfy the isolation characteristic between the terminating complex impedance ports. To prove the feasibility of this method, an unequal power divider with different load complex impedances with a splitting ratio k² = 3 dB and 1.7 dB and an unequal power divider with different complex termination impedances of all ports with a splitting ratio k² = 3 dB was designed at a center frequency of 2 GHz, and it was confirmed that the measured results of the electrical characteristics agree well the simulation.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.41 no.4
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• pp.51-58
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• 2004

Push-pull structure with balun transformer is presented for load modulation technique which improves the overall efficiency of power amplifier Under the assumption that output impedance of fumed-off amplifier is high, conventional Doherty amplifier is composed of impedance inverter and peaking amplifier, of which operation is controlled by the input power level. In many case, however, impedance of 'off'amplifier is very low due to matching network or parasitic output capacitance. This paper introduces novel load modulation technique which uses low output impedance of 'off'amplifier. Experimental results show that good linearity and efficient!'enhancement of the proposed push-pull structure

• Journal of the Institute of Electronics and Information Engineers
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• v.50 no.2
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• pp.47-53
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• 2013

In this work, signal transmission properties of SATA connector have been improved using its differential impedance calculation and its design revision to closer impedance matching. Using 3 dimensional electromagnetic field simulator, the differential mode S-parameter was calculated to investigate its signal fidelity. The differential impedance is calculated from the equation of the odd mode impedance with inductance, capacitance, mutual inductance, and mutual capacitance. The differential impedance of SATA connector was calculated to be $107.3{\Omega}$ and did not meet the design specification with $100{\Omega}{\pm}5%$. In order to achieve its impedance range and improve its signal transmission properties, SATA connector's design has been revised with two different directions and analyzed through the calculation of differential impedance, differential reflection loss, and differential insertion loss.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.46 no.6
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• pp.128-134
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• 2009

In this paper, we propose a new lumped Wilkinson power divider which is designed to have lower quality-factors in the impedance transformation. Therefore, it can provide wider bandwidth than the conventional one. Moreover, the proposed power divider consists of fewer number of elements so that the circuit size can be further reduced. Simulation results show that the proposed lumped power divider allows a 50% wider bandwidth in the return loss and isolation performance. The conventional and new Wilkinson power was designed and fabricated based on the derived equations at 2.0 GHz. In the measurement, the proposed divider achieved a good performance with an input return loss ($S_{11}$) of -23.0 dB, an isolation ($S_{23}$) of -29.0 dB and an insertion loss ($S_{21}$) of -3.12 dB at the design frequency with wider bandwidth than the conventional one.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.39 no.11
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• pp.28-33
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• 2002

In this paper, the impedance-tuned monopole microstrip antenna designed for PCS is analyzed using finite difference time domain(FDTD) method. The perfectly matched layer(PML) absorbing material condition proposed by Berenger is used for the truncation of finite difference time domain lattice. A Gaussian pulse is selected as an excitation signal and a resistive voltage source model is used to reduce the error caused by the reflection waves. The FDTD method is inherently a near field technique. Therefore, the near field to far field transformation is need to compute far field antenna parameters such as radiation patterns and gain. The near field to far field transformation can be done both in the time domain and the frequency domain. We use the frequency domain transformation to compute the far field radiation patterns at single frequency. All the numerical results obtained by the FDTD method are compared with simulation results using the HFSS software. Good agreements are obtained in all cases.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.19 no.5
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• pp.562-571
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• 2008

In this paper, we propose a novel structure of a spiral antenna with a CP characteristic for RFID reader in UHF band. Since the proposed antenna can be built by printing on a FR-4 substrate, it is appropriate for low-cost mass-production. The antenna is designed to operate in UHF band of $860{\sim}960$ MHz. The CP bandwidth is Increased enough to cover an overall UHF RFID band by using a spiral structure for the antenna arm. The matching bandwidth is broadened by using a quarter-wave transformer between the fred and the antenna body. The proposed antenna has advantages of its easy gain and pattern control with a small antenna size. The measured antenna performance shows the matching bandwidth of 13%, the CP bandwidth of 23%, and the gain of 6.5 dBi. This verifies that the proposed antenna is appropriate for RFID antennas in UHF band.