• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.11a
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• pp.103-107
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• 2003

The inductively coupled plasma(ICP) etching process was selected to fabricate RF Surface Acoustic Wave(SAW) filters and a Pt thin film was sputtered on a $LiTaO_3$ substrate applied to electrode materials to reduce the spurious response and improve the power durability. Steep sidewall pattern was achieved employing $C_4F_8/Ar/Cl_2$ gas chemistry. We investigated an etching mechanism and parameter dependence of the Pt thin film about $C_4F_8$ addition. Sidewall etch angle was about $80^{\circ}$ at the $C_4F_8$ 20% mixing ratio. Fabricated SAW filter is consists of some series and parallel arm SAW resonators which work as impedance elements and show capacitance characteristics at out of the passband. It can be modified for $800{\sim}900\;MHz$ RF filters. External matching circuits were unnecessary.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.28 no.6
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• pp.224-231
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• 2016

When aiming to reduce the low frequency noise of a subway guest room through sound absorbing treatment methods inside the wall of a tunnel the resonator is often more effective than a porous sound absorbing material. Therefore, the perforated panel type resonator embedded with a perforated panel is proposed. The perforated panel is installed in the neck, which is then extended into the resonator cavity so that it can ensure useful volume. The absorption performance of the perforated panel type of resonator is obtained by acoustic analysis and experiment. The analytical results are in good agreement with the experimental results. In the case of multiple perforated panel type resonators, as the number of perforated panels increase, the 1st resonance frequency is moved to a low frequency band and sound absorption bandwidth is extended on the whole. In order to obtain excellent absorption performance, the impedance matching between multi-panels should be considered. When the perforated panel in the resonator is combined with a porous material, the absorption performance is highly enhanced in the anti-resonance and high frequency range. In case of the resonator inserted with perforated panels of 2, the 2nd resonance frequency is shifted to a low frequency band in proportion to the distance between perforated panels.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.29 no.11
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• pp.842-850
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• 2018

In this paper, the design and fabrication of a frequency-locked-loop(FLL) 5-GHz oscillator with a single resonator is presented. The proposed oscillator is the simplified version of the previous FLL oscillator with two separate resonators in the VCO and frequency detector. The resonator is commonly used in the VCO and frequency detector of the proposed oscillator configuration. The 5-GHz oscillator is implemented on the hetero-multilayer substrate composed of a Rogers' RO4350B laminate, which has excellent high-frequency performance, and the commercial FR4 three-layer substrate. The frequency locking occurs at approximately 5 GHz and has an output power of 3.8 dBm. The phase noise has a free-run VCO phase noise at frequencies above 1 kHz, and an FLL background noise at frequencies below 1 kHz. For this loop-filter, the phase noise showed an improvement of approximately 12 dB at the offset-frequency of 100 Hz.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2014.10a
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• pp.157-158
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• 2014

In this paper, a design method for a compact CPW-fed slot antenna using SRRs(split-ring resonators) is studied. The structure of the proposed slot antenna is a rectangular slot antenna loaded with SRR conductors inside the slot to reduce the antenna size. Optimal design parameters are obtained by analyzing the effects of the gap between the SRR conductors and slot, and the width of the SRR conductors on the input reflection coefficient characteristic. The optimized compact slot antenna operating at 2.45 GHz band is fabricated on an FR4 substrate with a dimension of 36 mm by 30 mm. The length of the proposed compact slot antenna is reduced by 14.3% compared to that of a conventional rectangular slot antenna. Experiment results show that the antenna has a desired impedance characteristic with a frequency band of 2.4-2.49 GHz for a VSWR < 2.

• Journal of IKEEE
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• v.23 no.3
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• pp.1112-1115
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• 2019

This paper proposes a novel low-profile omni-directional microstrip antenna to mount on the deployable wing of the observation munition. The proposed antenna is designed on seven hexagonal resonators in a quasi-circular array to achieve a monopolar radiation pattern with a thin substrate. By employing the mesh ground structures, the resonant frequencies and impedance bandwidths of the proposed antenna is investigated. To verify the feasibility of the mesh ground structure, the thin ground wire width is investigated theoretically for improving the 3-dB fractional bandwidth, realized antenna gain and quality-factor. The proposed antenna demonstrates a good monopolar radiation in good agreement with the simulation results. The implemented prototype shows the measured bandwidth of 326 MHz with respect to 5.65% centered at 5.77 GHz and realized gain of 5.49 dBi at 5.84 GHz.

• Journal of Advanced Navigation Technology
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• v.25 no.1
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• pp.90-95
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• 2021

In this paper, the design method for a high-sensitivity compact resonator for chipless RFID tags is proposed. Proposed high-sensitivity compact resonator uses an interdigital-capacitor structure instead of a capacitor-shaped strip structure in a conventional ELC resonator. The length of the electrode plate of the IDC structure is longer than that of the conventional capacitor-shaped structure, resulting in a larger equivalent capacitance of the resonator. This can lower the resonant peak frequency of the RCS characteristic. Two resonators with the same length of the square loop and the width of the strip are fabricated on an RF-301 substrate with a thickness of 0.8 mm. The experiment results show that the resonant peak frequency and value of the bistatic RCS for the ELC resonator were 4.305 GHz and -30.39 dBsm, whereas those of the proposed IDC resonator were 3.295 GHz and -36.91 dBsm. Therefore, the size of the resonator is reduced by 23.5% based on the measured resonant peak frequency of the RCS characteristic.

• Progress in Superconductivity
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• v.13 no.2
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• pp.97-104
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• 2011

In the dielectric resonator method, which has been widely used for measuring the microwave surface resistance of superconductors, accuracies in the geometrical factors (G-factors) affect the uncertainty in the measured surface resistance. We compare the G-factors of short-ended sapphire resonator as obtained by using field analysis with those by using computer simulations: The former is obtained by using the analytic expressions for the electric and the magnetic field components inside the resonator, and the latter by using computer software. The G-factors as obtained by using the latter appear to be closer to those obtained by using the former as the resonator space is divided into larger number of sub-space, i.e., a tighter mesh, with a difference of ~8 % observed for a mesh of 14400 sub-spaces reduced to ~2 % for 114996 sub-spaces. Variations in the relative uncertainty in the surface resistance of typical $YBa_2Cu_3O_{7-\delta}$ superconductor films with those in the G-factors are studied, which provides an upper limit of the relative uncertainty in the G-factors required for realizing the target uncertainty in the surface resistance. These results could be useful in estimating the optimum number of meshes for obtaining the G-factors through computer simulations.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.11
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• pp.635-639
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• 2016

In the devices used in the microwave frequency band, the gain decreases as the frequency increases due to the parasitic component. To compensate for these characteristics, a linear gain equalizer with an opposite slope is needed in wideband systems, such as those used for electronic warfare. In this study, a linear gain equalizer that can be used in the 18 ~ 40GHz band is designed and fabricated. Circuit design and momentum design (optimizations) were carried out to reduce the errors between design and manufacturing. A thin film process is used to minimize the parasitic components within the implementation frequency band. A sheet resistance of 100 ohm/square was employed to minimize the wavelength variation due to the length of the thin film resistor. This linear gain equalizer is a structure that combines a quarter wavelength-resonator on a series microstrip line with a resistor. All three 1/4 wavelength short resonators were used. The fabricated linear gain equalizer has a loss of more than -5dB at 40GHz and a 6dB slope in the 18 ~ 40GHz band. By using the manufactured gain equalizer in a multi-stage connected device such as an electronic warfare receiver, the gain flatness degradation with increasing frequency can be reduced.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.21 no.2
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• pp.194-201
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• 2010

We propose a frequency selective surface(FSS) using double split ring resonators(DSRRs) for isolation enhancement between CDMA and RFID. The structure consists of an outer SRR and an inner SRR, and the gaps are formed in the same direction. By properly adjusting the gap and line width, the resonant frequency and skirt characteristics can be adjusted without varying the unit cell size. The proposed structure has a different field distribution from that of an ordinary SRR for magneto-dielectric materials. One layer consists of $9{\times}9$ unit cells and the other layer was separated by 50 mm. To validate the simulation results, we fabricated the patch antenna and the FSSs, and the measured results show a good agreement with the simulated ones. The electrical size of the unit cell is $0.110\;{\lambda}{\times}0.110\;{\lambda}{\times}0.002\;{\lambda}$, and the size of the two layer FSS is $1.058\;{\lambda}{\times}1.058\;{\lambda}{\times}0.153\;{\lambda}$. The two layer FSS maintain gain in CDMA frequency and has 6.9 dB reduced gain in RFID frequency.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.28 no.1
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• pp.69-75
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• 2017

In this paper, slit ground resonator with slit and capacitor is proposed for practical use of magnetic resonant wireless power transfer(MR-WPT). And this paper presents the performance comparison of conventional loop resonator as Rx resonator to slit ground resonator. The proposed silt ground resonator with 31 cm width, 20.5 cm length, $35{\mu}m$ thickness is designed the crossing slit 1 cm width with only opened edge. And an external capacitors were connected at the opened edge of slit ground resonator for resonating at 6.78 MHz. The transfer efficiencies of MR-WPT were measured at open and short mode, and then the highest transfer efficiencies of MR-WPT according to the Rx resonators were plotted. In result, the transfer efficiency of MR-WPT with loop resonator was the highest. However, when the ground was inserted in receiver part at the bottom of laptop model, the transfer efficiency was closed 0 %. The transfer efficiency recovered the transfer efficiency of 67 % using slit ground resonator. The magnetic field was penetrated through the slit and proposed slit ground resonator works as resonator in MR-WPT.