• Journal of the Korea Academia-Industrial cooperation Society
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• v.7 no.6
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• pp.1106-1115
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• 2006

In this paper, the transmission characteristics and equivalent circuit model of microstrip transmission line having defected ground structure (DGS) in multilayer substrates are described fur high frequency region. In order to perform the study, the second dielectric layer is attached additionally onto the bottom(ground) plane of the basic DGS microstrip line consisted of the microstrip line and DGS. The dielectric constant and thickness of the second dielectric layer are adjusted to get various transmission characteristics and model parameters, and to analysis the effect of the second dielectric layer ultimately. According to this paper, the effect and equivalent circuits due to the attached dielectric substrate are verified separately, and this is expected to be applied to high frequency circuit design in the future.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.2 no.4
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• pp.59-64
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• 2009

In this paper, we represent characteristics and equivalent circuit of donut type resonator of defected ground structure (DGS), and can control resonant frequency with chip capacitor. In General, DGS operates like with parallel LC resonator. We found out variation of resonance frequency when capacitor is placed on slot of DGS. If the chip capacitor replace with varactor diode, the resonance frequencies can be controlled by voltage. This tualable resonator can apply to voltage controlled oscillator and tunable bandpass filter.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.17 no.1 s.104
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• pp.1-7
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• 2006

New phase shifters with higher phase shift values are presented using defected ground structures(DGSs). The varactor diodes are mounted on DGSs of termination loads to control the large phase variation of the DGS at resonance. Two types of phase shifters are implemented with a branch-line and a coupled line hybrid. The experimental results of the proposed phase shifters show $135\%$ and $221\%$ increases in maximum phase shills, respectively, compared with those of conventional ones.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.7
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• pp.3474-3481
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• 2013

In this work, a new high frequency transmission line structure combined with defected ground structure (DGS) and artificial dielectric substrate (ADS) structure is proposed. DGS patterns give add the additional inductance to transmission lines and results in the increased characteristic impedance for a given line width. To the contrary, ADS presents increased capacitance and reduced line impedance. So both play a role in reducing the length of transmission lines commonly, but in preserving the line impedance complementarily. This means that the length of transmission lines can be reduced furtherly by DGS and ADS without a critical change of line width compared to the cases when one of DGS and ADS is used only. As examples, $35{\sim}100{\Omega}$ transmission lines having DGS and ADS are designed, fabricated, measured, and compared to the simulation results. A good agreement between the simulated and measured line impedances is presented. In addition, the physical lengths of the proposed transmission lines are only 55.4~76.9% of those of the normal microstrip lines for the same electrical lengths.

• Proceedings of the KAIS Fall Conference
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• 2010.11a
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• pp.85-87
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• 2010

본 논문에서는 공통 결함접지구조를 이용하여 브랜치 라인 하이브리드 커플러 회로를 소형화하여 설계한 결과를 제시한다. 브랜치 라인 하이브리드 커플러 회로는 가장 널리 쓰이는 전자파회로중 하나이다. 본 논문에서 제안하는 공통 결함접지구조를 이용하여 소형화한 커플러 회로는 크기가 소형화되었음에도 불구하고, 기존 커플러 구조와 유사한 정합, 격리 및 전력분배 특성을 보여준다.

• Journal of Advanced Navigation Technology
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• v.24 no.6
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• pp.627-632
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• 2020

In this paper, we have studied a development of a humidity sensor using a microwave sensor based on a microstrip defected ground structure coated with polyvinyl alcohol. A high-sensitivity microwave sensor, which is sensitive to the changes in the permittivity of the material under test, is designed by adding an interdigital capacitor-shaped defected ground structure to the ground plane of a microstrip line. Polyvinyl alcohol, a polymer material whose permittivity varies depending on humidity, is coated with a thin thickness on the defected ground structure of the proposed microwave sensor, and the changes in the resonance frequency and magnitude of the transmission coefficient for the microwave sensor according to humidity are measured. When relative humidity increases from 40% to 80% in 10% increments at a temperature of 25 degrees using a temperature/humidity chamber, the resonant frequency of the transmission coefficient decreases from 1.475 GHz to 1.449 GHz, and the magnitude is increased from -32.90 dB to -25.67 dB.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.7 no.4
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• pp.616-624
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• 2006

In this paper, the transfer characteristics of high frequency transmission line having defected ground structure (DGS) and lumped elements are described. When a DGS, which is a kind of periodic structure, is inserted into a transmission line, its equivalent inductance and capacitance elements are added to the characteristics of the standard transmission line. This generates resonance, 3dB cut-off frequency, low-pass, band rejection, and band pass characteristics, and causes a slow-wave and enlarged electrical length of the transmission line. In addition, if the DGS is combined by a lumped element such as resistor, capacitor, and inductor, the resonant and cut-off frequencies moves up or down and other changes occur in the transmission characteristics. The variation of the transmission characteristics is described with the qualitative prediction and measured data.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.18 no.11
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• pp.1291-1298
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• 2007

A novel 1:4 unequal wilkinson power divider using rectangular-shaped defected ground structure(DGS) in double layered substrate is proposed for removing the ground problem of DGS in packaging. Rectangular-shared DGS produces the transmission line having much higher characteristic impedance than standard microstrip line. The proposed unequal divider is composed of DGS and double layered substrate in order to be free from the ground problem of DGS patterns in packaging in metal housings. The second substrate is attached to the first substrate which contains DGS pattern on its ground plane at the bottom side to form the double layered substrate. In order to show the validity of the proposed DGS in the double layered substrate, a 1:4 unequal power divider is designed and measured. The predicted and measured performances are shown with an excellent agreement between them.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.13 no.9
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• pp.1745-1752
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• 2009

This Paper represents a new method, which uses defected ground structure (DGS) on the ground planes of microstrip lines, to reduce the size of the Schiffman phase shifter. DGS on the microstrip line shows an increased slow-wave effect due to the additional equivalent L and C components. So the electrical length of transmission line with DGS is longer than that of standard transmission line for the same physical length. Then, the length of transmission line with DGS can be shortened in order to maintain the original electrical length to be same. The performances of reduced phase shifter with DGS are quite similar to the ones of original Schiffman phase shifters. We can reduce the size about 15% using the DGS in original Schiffman phase shifter.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.17 no.10
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• pp.2233-2238
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• 2013

A novel design method of ultra wideband based on the composite right-/left handed (CRLH) transmission line is presented in this paper. Defected ground structure and microstrip interdigital coupler are used to implement the CRLH transmission line. The proposed CRLH transmission line in this paper have composite characteristics of low pass filter and high pass filter, also it has good advantages of low insertion loss and ultra wide passband characteristics. The structure with different cell number are studied, and the UWB filter using 3-cell CRLH transmission line is fabricated and measured, which shows a good agreement between simulated and measured results. It has center frequency of 5 GHz, fractional bandwidth of 105 %, and insertion loss of 0.7 dB at center frequency.