• The Transactions of The Korean Institute of Electrical Engineers
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• v.56 no.6
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• pp.1099-1104
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• 2007

A 1:6 Unequal 2-way Wilkinson power divider is proposed. The required microstrip line with $207{\Omega}$ characteristic impedance for 1:6 power divider is realized by adding defected ground structure (DGS) to the standard microstrip line. The adopted DGS has the rectangular geometry which results in the increased characteristic impedance. The rectangular-shaped DGS produces the transmission line having much higher characteristic impedance due to the increased equivalent inductance. The measured performances of the fabricated 1:6 power divider show the expected S-parameters with a good agreement with the predicted ones.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.57 no.11
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• pp.2041-2046
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• 2008

A frequency-dependent slow-wave factor (SWF) and equivalent circuit model of transmission line with defected ground structures (DGS) is described. Once S-parameters of a DGS transmission line are given, the conventional frequency -independent equivalent circuit elements are extracted using 3dB cutoff and resonant frequencies (Fc and Fo) as the first step. Using the initial equivalent elements and simple transmission line theories, a frequency-dependent equivalent transmission line model is established through an analytical method, and finally the frequency dependent SWF is calculated. The proposed equivalent circuit model and SWF are frequency-dependent and more reliable because even small insertion loss within available passband is considered, while they have been independent of frequency.

• 한국정보통신설비학회:학술대회논문집
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• 2003.08a
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• pp.3-6
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• 2003

Effect to altered geometry of a suggested defected ground structure(DGS) unit cell was investigated . And equivalent circuit model was extracted from the DGS unit cell A microstrip band Pass filter with DGS has been designed in this Paper. The BPF with DGS was fabricated and obtained experimental results with network analyzer HP8510C. Experimental results show the center frequency of 2.45GHz, the insertion loss of 0.85dB, and the 3-dB bandwidth of 470MHz (19.5%). The center frequency of BPF is 2.4GHz which is available for wireless LAN.

• 한국정보통신설비학회:학술대회논문집
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• 2004.08a
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• pp.386-389
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• 2004

This thesis complemented the weak points that the existing theses did not represented a phase characteristic as the equivalent circuit by applying 4-port simulation to DGS (Defected Ground Structure) characteristic and an equivalent circuit, which are the transmission line structure that has the defect made in the ground surface. We used a distribute device and a lumped device, obtained the equivalent circuit by applying the structure of balun to a discontinuous part. An indicated DGS (Defected Ground structure) is a dumbbells-shaped single defect, we indicated satisfying a magnitude and phase characteristics by applying this equivalent circuit.

• ETRI Journal
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• v.28 no.1
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• pp.84-86
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• 2006

This letter presents a small-sized, high-power single-pole double-throw (SPDT) switch with defected ground structure (DGS) for wireless broadband Internet application. To reduce the circuit size by using a slow-wave characteristic, the DGS is used for the quarter-wave (${\lambda}$/4) transmission line of the switch. To secure a high degree of isolation, the switch with DGS is composed of shunt-connected PIN diodes. It shows an insertion loss of 0.8 dB, an isolation of 50 dB or more, and power capability of at least 50 W at 2.3 GHz. The switch shows very similar performance to the conventional shunt-type switch, but the circuit size is reduced by about 50% simply with the use of DGS patterns.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2003.11a
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• pp.343-346
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• 2003

A new structure to design low pass filters (LPFs) is presented rho proposed structure has the etched shape of Quad-Spiral DGS(Defected Ground Structure) on microstrip transmission lines. By extracting the equivalent circuit elements of unit Quad-Spiral DGS, LPFs are designed easily. The equivalent circuit of Quad-Spiral DGS consists of a step impedance resonator and lumped elements. The proposed LPF provided steep rejection characteristics with 5-poles. Experimental results show excellent agreements with circuit simulation results in wide band and the validity of our circuit modeling for LPF design. The result shows another possibility of Quad Spiral DGS for microwave devices.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2003.11a
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• pp.333-337
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• 2003

In this paper, 5.2 GHz WLAN BPF(Band Pass Filter) using LTCC(Low temperature co-firing ceramic) Multilayer technology was simulated and manufactured. A DGS(Defected Ground structure) resonator with spiral ground pattern is used to shorten resonator size and improve circuit Q factor. And the equivalent circuit of BPF was suggested. The measured result shows good agreement with simulated data. Experimental results show the center frequency of 5.25GHz, the insertion loss of 0.14dB, and the 3-dB bandwidth of 350MHz (6%). The center frequency of BPF is 5.25GHz which is available for wireless LAN.

• Proceedings of the KIEE Conference
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• 2001.11b
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• pp.231-233
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• 2001

Nowadays, small scale DGS(Distributed Generation System), as a wind power generation or photovoltaic generation, becomes to be introduced into the power distribution system. But in that case, it is difficult to properly maintain the terminal voltage of low voltage customers. So, it is necessary to determine the permissible operation limit of the introduced DGS for proper voltage in distribution system. In this paper computes permissible operation limit of DGS when the DGS is connected to power distribution system using fixed tap(without LDC operation). For this simulation, KEPCO distribution system is used.

• Proceedings of the KIEE Conference
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• 2001.07a
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• pp.19-21
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• 2001

Nowadays, small scale DGS(Distributed Generation System), as a wind power generation or photovoltaic generation, becomes to be introduced into the power distribution system. But in that case it is difficult to properly maintain the terminal voltage of low voltage customers by using only LDC(Line Drop Compensator). So, it is necessary to determine the permissible operation limit of the introduced DGS for proper voltage in distribution system. In this paper clarifies the relationship between LDC voltage regulation principle and real, reactive power of DGS, and examines the permissible operation limit of the introduced DGS in distribution system which the voltage is controlled by LDC.

• Journal of electromagnetic engineering and science
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• v.14 no.4
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• pp.415-418
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• 2014

This paper presents an equivalent circuit model for a dumbbell-shaped defected ground structure (DGS) in a microstrip line. The effects of equivalent circuit elements of a dumbbell-shaped DGS and their magnetic coupling to the host transmission line are modeled as a simple lumped-element circuit. In addition, simple approximate expressions to determine the main circuit parameters for this model are presented. The transfer characteristic calculated by the proposed circuit model is compared with the results of EM simulation and measurement.