• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2002.11a
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• pp.109-112
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• 2002

So far, the closed-form Green's functions have been derived almost for th open microstrip structures. In the present study, closed-form Green's functions for a top-covered microstrip structure are derived. And an effect of top-cover is discussed in comparison with open structure.

• 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.17-23
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• 2006

This paper has presented a low phase noise oscillator using a square open loop with microstrip structure. A square open loop resonator has a large coupling coefficient value, which makes a high Q value, and has reduced phase noise. This oscillator has presented the oscillation frequency of 5.84 GHz, harmonics of -15.83 dBc and the phase noise of -111.17 dBc/Hz at the offset frequency of 100 kHz. In conclusion, the proposal structure has improved phase noise of 15 dB at the offset frequency of 100 kHz compared with the conventional structure of oscillator.

• Journal of electromagnetic engineering and science
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• v.11 no.4
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• pp.235-238
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• 2011

In this paper, a novel low phase noise voltage-controlled oscillator (VCO) using metamaterial structure and rat race coupler is presented for reducing the phase noise without the reduction of the frequency tuning range. The metamaterial structure has been realized by microstrip square open loop double split ring resonator (SRR). The rat race coupler shows slightly higher transmission compared to a Wilkinson combiner and is, therefore, used instead to improve the performances of VCO. By providing these unique modifications, the proposed push-push VCO has a phase noise of -126.30~-124.83 dBc/Hz at 100 kHz in the tuning range of 5.672~5.800 GHz.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2006.10a
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• pp.79-84
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• 2006

A novel design of compact low-pass filter based on microstrip structure and its equivalent-circuit model are developed. The philosophy of the structure behind this novel microstrip low-pass filter is simple as it is composed of a pair of symmetrical parallel coupled-line and an open-stub. With this configuration, a finite attenuation pole near the stopband cutoff frequency is available and adjustable by simply tuning the circuit parameters. Furthermore, the rejection bandwidth of this type of low-pass filter can be extended. In order to validate the feasibility of the proposed design method, a low-pass filter based on a microstrip structure is designed, fabricated, and measured. Experimental results agree very well with the simulation and analytical results.

• Journal of Navigation and Port Research
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• v.30 no.7
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• pp.607-610
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• 2006

A new compact microstrip low-pass filter and its equivalent-circuit model are developed. The philosophy of the structure behind this novel microstrip low-pass filter is simple as it is composed of a pair of symmetrical parallel coupled-line and an open-stub. With this configuration, a finite attenuation pole near the stopband cutoff frequency is available and adjustable by simply tuning the circuit parameters. Furthermore, the rejection bandwidth of this type of low-pass filter can be extended. In order to validate the feasibility of the proposed design method, a low-pass filter based on a microstrip structure is designed, fabricated, and measured. Experimental results agree very well with the simulation and analytical results.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.47 no.12
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• pp.84-89
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• 2010

In this paper, a novel voltage-controlled oscillator (VCO) using the microstrip square open loop dual split ring resonator is presented for reducing the phase noise. The square-shaped dual split ring resonator having the form of the microstrip square open loop is investigated to reduce the phase noise. Compared with the microstrip square open loop resonator and the microstrip square open loop split ring resonator as well as the conventional microstrip line resonator, the microstrip square dual split ring resonator has the larger coupling coefficient value, which makes a higher Q value, and has reduced the phase noise of VCO. The VCO with 1.7V power supply has the phase noise of -123.2~-122.0 dBc/Hz @ 100 kHz in the tuning range, 11.74~11.75 GHz. The figure of merit (FOM) of this VCO is-214.8~-221.7 dBc/Hz dBc/Hz @ 100 kHz in the same tuning range. Compared with VCO using the conventional microstrip line resonator, VCO using microstrip square open loop resonator, the phase noise of VCO using the proposed resonator has been improved in 26 dB, 10 dB, respectively.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2005.04a
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• pp.55-58
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• 2005

The present study aims to design electrically and structurally effective antenna structures in order that the structural surface itself could become the antenna. The basic design concept is composite sandwich structure in which microstrip antenna is embedded and this is termed composite smart structure (CSS). The most important outstanding problem is that composite materials of structural function cannot be used without reducing antenna efficiency. Unfortunately, such materials have high electrical loss. This is a significant design problem that needs to be solved in practical applications. Therefore, the effects of composites facesheet on antenna performances are investigated in the first stage and changes in the gain of microstrip antenna due to composites facesheet have been determined. ‘Open condition’ is defined when gain is maximized and is a significant new concept for the design of high-gain antennas considering bandwidth in practical application. The open condition can be made with the outer facesheet by controlling its position. In the design of CSS, glass/epoxy composites and Nomex honeycomb were used with exploiting open condition. Experiments, confirm that the gain is improved and the bandwidth is also as wide as specified in our requirements. With the open condition, wideband antenna can be integrated with mechanical structures without reducing any electrical performances, as confirmed experimentally here.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2005.05a
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• pp.346-349
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• 2005

The present study aims to design electrically and structurally effective antenna structures in order that the structural surface itself could become the antenna. The basic design concept is composite sandwich structure in which microstrip antenna is embedded and this is termed composite smart structure (CSS). The most important outstanding problem is that composite materials of structural function cannot be used without reducing antenna efficiency. Unfortunately, such materials have high electrical loss. This is a significant design problem that needs to be solved in practical applications. Therefore, the effect of composites facesheet on antenna performances is studied in the first stage. Changes in the gain of microstrip antenna due to composites facesheet have been determined. 'Open condition' is defined when gain is maximized and is a significant new concept in the design of high-gain antennas considering bandwidth in practical application. The open condition can be made with any thickness of outer facesheet by controlling its position. In the design of CSS, glass/epoxy composites and Nomex honeycomb were used with exploiting open condition. Experiments, confirm that the gain is improved (over 11 dBi) and the bandwidth is also as wide as specified in our requirements (over 10% at 12.2 GHz). With the open condition, wideband antenna can be integrated with mechanical structures without reducing any electrical performances, as confirmed experimentally here.

• 한국정보통신설비학회:학술대회논문집
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• 2006.08a
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• pp.158-161
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• 2006

In this paper, we deal with EMI Analysis on Microstrip with Defected Ground plane. Specially, we investigate reflection, transmission, crosstalk, radiated emission on Microstrip with Defected Ground plane structure. And investigates undesired effects on various defected ground plane such as ground with split, slot, short end and open end gap. To analyze reflection, transmission and crosstalk of microstrip with defected ground plane, we used concept of the microstrip to slot line transition model. Besides, investigate radiated emission using FDTD Commercial tools such as CST MW

• Journal of electromagnetic engineering and science
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• v.1 no.1
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• pp.63-66
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• 2001

In order to derive simple and accurate closed-form spatial Greep’s functions for the thick microstrip substrate, an efficient method based on the two-level approach, which circumvents the burdensome steps (i.e., without necessity of extraction of quasi-static contributions and subsequent determination of approximation parameters) in the previous complex image method, is considered in conjunction with the use of the original Prony`s method. The present method is observed to give more accurate results for the evaluation of the Green`s functions over wider frequency range independently of the source-to-field distances than the previous method.