• 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.

• 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.

• 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.

• 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.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.19 no.7
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• pp.785-790
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• 2008

In this paper, a new balun is proposed. This proposed balun has a DGS(Defected Ground Structure) pattern on the ground plane. The transmission-line is transformed by microstrip-to-slotline transition. DGS pattern on the ground plane and transition of the lines can be easily made a property of the balun. Resonance frequency of the DGS leads to operating frequency of the balun. Also the transition produces $180^{\circ}$ out-of-phase between two output ports without additional transmission line. In this paper, a new balun with VPDGS(Vertically Periodic Defected Ground Structure) effectively lower the operating frequency. To validate the proposed design method, the new balun is designed, fabricated and measured at 2 GHz.

• The Journal of the Korea institute of electronic communication sciences
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• v.10 no.6
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• pp.653-658
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• 2015

In this paper, the Square Split Ring Resonator(: SRR) of Defected Ground Structure(: DGS), applicable to MMIC(: Monolithic Microwave Integrated Circuit) design, is proposed. The mathematical method to solve the equivalent parameter of the resonator from the measured results of resonator is introduced in this paper. To verify the method, SRR-DGS resonator with 2.95 GHz center frequency is fabricated, for measuring characteristics and calculating the equivalent parameter. The result from this process is compared with the data of the ADS simulation, and as a result both were identical.

• 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 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 Institute of Electronics and Information Engineers
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• v.50 no.11
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• pp.36-40
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• 2013

A novel design method of ultra wideband bandpass filter using CRLH transmission line with Dumbell type DGS is presented in this paper. Defected Ground Structure and microstrip interdigital capacitor are used to design the ultra wideband (UWB) filter. CRLH transmission line has composite characteristics of low pass and high pass filter. As control of cutoff frequency of low pass and high pass response on CRLH transmission line, we can get characteristic of UWB filter. We designed and simulated for CRLH transmission lines with one, two, four, and eight cells. A UWB filter using four cells CRLH is designed and fabricated to verify the results. The characteristics of designed filter have center frequency of 5GHz and relative bandwidth of 88%.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2008.10a
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• pp.299-302
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• 2008

In this paper, A compact ultra-wideband(UWB) bandpass filter(BPF) with WLAN notched filter has been proposed. H-shaped slot is studied and adopted to tighten the coupling of inter-digital capacitor in order to improve the BPF's performance. Three pairs of tapered defected ground structures(DGS) are formed to assign their transmission zeros towards the out of band signal, thereby suppressing the spurious passband. Also Meander line slot is developed to reject the undesired wireless local-area network(WLAN) radio signals. That's combining these three structures we obtain a small sized UWB BPF.