• Progress in Superconductivity and Cryogenics
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• v.22 no.4
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• pp.10-13
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• 2020

High-quality superconducting coplanar waveguide (SCPW) resonators are crucial for developing superconducting quantum information devices and sensors. We designed quarter-wavelength SCPW resonators and fabricated the SCPW resonators using Nb thin film. The resonant characteristics were measured at T = 4.2 K, revealing the intrinsic quality factor and the coupling quality factor to be Qi = 4,784 and Qc = 17, 980, respectively. Our design and fabrication techniques would be very useful to develop a gate-tunable superconducting qubit based on the semiconductor nanostructures.

• Current Optics and Photonics
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• v.5 no.6
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• pp.730-737
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• 2021

Transmission spectra are measured from waveguide-coupled ring resonators fabricated with SiN_x on SiO₂. By using ring resonators with various radii and several index contrasts, the behavior of the quality factors is investigated. As the index contrast decreases, the dominant loss is from scattering for a large resonator, while that changes from scattering loss to bending loss for a small resonator. We verify that the quality factor can be drastically improved by reducing the index contrast in large ring resonators.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.23 no.3
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• pp.343-354
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• 2012

In this paper, various spiral zeroth-order resonators are proposed for wireless power transmission. Since a zerothorder resonance(ZOR) mode of meta-material transmission lines has the characteristic of an infinite wavelength, its frequency is independent of physical length. Also, to obtain high transmission efficiencies high-Q resonators and strong coupling coefficient between coupled resonators are required. Therefore, the resonators consist of spiral inductor and lumped capacitor to use the ZOR mode and they are optimized via parametric study and circuit analysis for a high-Q resonator design. The optimized resonators are simulated and compared with a conventional spiral resonator and one of them was fabricated and measured. The fabricated one has a dimension of $20cm{\times}20cm{\times}8cm$($0.009{\lambda}_0{\times}0.009_{\lambda}_0{\times}0.004{\lambda}_0$) and the transmission efficiency of 80 % is measured at 13.56 MHz at transmitted distance of 40 cm.

• Journal of the Korean Society of Propulsion Engineers
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• v.10 no.1
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• pp.1-8
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• 2006

A linear acoustic analysis is conducted to examine bituning of acoustic resonators for acoustic damping in a combustion chamber of liquid rocket engine. Bituned resonators are tuned to the two principal modes, the first tangential(1T) and the first radial(1R) modes. First, the acoustic-damping effect of monotuned resonators is investigated. The damping capacity is quantified by damping factor as a function of the number of the resonators monotuned to 1T or 1R mode. Next, the damping characteristics of the bituned resonators are investigated. From the numerical data, the number of resonators, to be tuned to 1T and 1R modes, respectively, can be selected properly. Furthermore, the concept of resonator bituning is applied to reduce the degradation of damping effect caused by the mode split and thereby, optimal bituning frequencies are found.

• Journal of the Korean Ceramic Society
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• v.40 no.4
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• pp.393-397
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• 2003

To investigate the effect of AIN c-axis orientation on the resonance performance of film bulk acoustic wave resonators, solidly mounted resonators with crybtallographically different AIN piezoelectric films were prepared by changing only the bottom electrode surface conditions. As increasing the degree of c-axis texturing, the effective electromechanical coupling coefficient ($\kappa$$\_$eff/)$^2$ in resonators increased gradually. The least 4 degree of full width at half maximum in an AIN(002) rocking curve, which corresponds to $\kappa$$^2$$\_$eff/ of above 5%, was measured to be necessary for band pass filter applications in wireless communication system. The longitudinal acoustic wave velocity of AIN films varied with the degree of c-axis texturing. The velocity of highly c-axis textured AIN film was extracted to be about 10200 n/s by mathematical analysis using Matlab.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2005.11a
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• pp.7-12
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• 2005

A compact microstrip band-selective filter for ultra-wideband (UWB) radio system is proposed. The filter combines the traditional short-circuited stub highpass filter and coupled resonator bandstop filter on both sides of the mitered 50-ohm microstrip line. To realize the pseudo-highpass filtering characteristic over UWB frequency band (3.1 GHz to 10.6 GHz), a distributed highpass filter scheme is adopted. Three coupled resonators are utilized to obtain the band stop function at the desired frequency band. By meandering the coupled resonators, there is 29% reduction in footprint compared to the traditional bandstop filter using L-shaped resonators. The measured results show that the filter has a wide passband of 146.7 % (2.1 GHz to 10.15 GHz) with low insertion loss and the stop band of 7.42 % (5.32 GHz to 5.73 GHz) for 3-dB bandwidth. The measured group delay is less than 0.7 ns within the passband except the rejection band.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.25 no.5
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• pp.361-365
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• 2012

A bolt-clamped ultrasonic viscometer was designed and fabricated using a pair of ring-shaped piezoelectric ceramic resonators. For its compactness and low operation frequencies, simulation of piezoelectric resonators was carried out using an ATILA program. Ring-shaped resonators using $0.05Pb(Mn_{1/3}Sb_{2/3})O_3-0.95Pb(Zr_{0.475}Ti_{0.525})O_3$ ceramics were prepared by a conventional ceramic processing, which were then clamped with a pair of metal caps. The fabricated sensor module with a small volume of less than 1 $cm^3$ and an operation frequency as low as 26.5 kHz showed a good relationship between its quality factor and the viscosity of oil.

• Journal of Power Electronics
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• v.12 no.4
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• pp.654-663
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• 2012

In this paper, a digital control strategy based on equivalent fundamental and odd harmonic resonators is proposed for single-phase DVRs. By using a delay block, which can be equivalent to a bank of resonators, it rejects the fundamental and odd harmonic disturbances effectively. The structure of the single closed-loop control system consists of a delay block, a proportional gain and a set of zero phase notch filters. The principle of the controller design is discussed in detail to ensure the stability of the system. Both the supply voltage and the load current feedforwards are used to improve the response speed and the ability to eliminate disturbances. The proposed controller is simple in terms of its structure and implementation. It has good performances in harmonic compensation and dynamic response. Experimental results from a 2kW DVR prototype confirm the validity of the design procedure and the effectiveness of the control strategy.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.16 no.1 s.92
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• pp.78-83
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• 2005

LTCC filters have been widely used to wireless terminals. They generally adopt the multilayer structure. Some of multilayer LTCC filters are made of symmetrical parallel-coupled lines and anti-symmetrical parallel-coupled lines to reduce the length of resonators. The equivalent circuit of parallel-coupled lines was analyzed and applied to bandpass filters using multilayer parallel-coupled line resonators. The three-pole bandpass filter with the center frequency of 2.45 GHz is designed by using the proposed equivalent circuit and the measured results have good agreement with the design results.

• Journal of the Institute of Electronics and Information Engineers
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• v.54 no.5
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• pp.128-132
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• 2017

In this thesis, a BPF(band-pass filter) at the center frequency of 2.14GHz, and bandwidth of 20MHz is designed and implemented using high Q dielectric resonators with ${\varepsilon}_r=38$. The DR(dielectric resonator) is resonated by $TE_{01{\delta}}$-mode and it has a hole in the center of DR. The BPF consists of 6-poles dielectric resonators and the characteristic of elliptic function is obtained by non-adjacent coupling. It has the average insertion loss of 0.97dB and the return loss over 25dB in its passband. In this thesis, the frequency selectivity is more improved by the coupling characteristics between non-adjacent resonators than that of dielectric resonator filters with a Chebyshev response.