• Title/Summary/Keyword: Resonance mode

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Resonance Frequency and Bandwidth of the Negative/Positive nth Mode of a Composite Right-/Left-Handed Transmission Line

  • Kim, Seong-Jung;Lee, Jeong-Hae
    • Journal of electromagnetic engineering and science
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    • v.18 no.1
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    • pp.1-6
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    • 2018
  • In this study, the analytic expression for the positive/negative $n^{th}-Mode$ resonance frequency of an N unit cell composite right-/lefthanded (CRLH) transmission line is derived. To explain the resonance mechanism of the $n^{th}$ mode, especially for the negative mode, the current distribution of the N unit cell CRLH transmission line is investigated with a circuit simulation. Results show that both positive and negative $n^{th}$ resonance modes have n times current variations, but their phase difference is $180^{\circ}$ as expected. Moreover, the positive $n^{th}$ resonance occurs at a high frequency, whereas the negative $n^{th}$ resonance transpires at a low frequency, thus indicating that the negative resonance mode can be utilized for a small resonator. The correlation between the slope of the dispersion curve and the bandwidth is also observed. In sum, the balanced condition of the CRLH transmission line provides a broader bandwidth than the unbalanced condition.

A Wide-band Multi-layer Antenna Design using Double Resonance (이중공진을 사용한 적층기판용 광대역 안테나 설계)

  • Lee, Kook-Joo;Zhang, Mei-Shan;Lee, Jung-Aun;Han, Myeong-Woo;Kim, Moon-Il
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.60 no.2
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    • pp.431-434
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    • 2011
  • In this paper, bandwidth enhanced design of dielectric resonator antenna fabricated in multi-layer substrate is introduced. The proposed dielectric resonator antenna is operating with fundamental TE101 mode and higher-order TM111 mode. Each resonance frequency is dependent on resonator dimensions. As increasing the height of radiating aperture, the higher-order TM111 mode resonance frequency approach the fundamental TE101 mode resonance frequency and the antenna bandwidth increase by double resonance. Three different aperture height size antennas that operated at 7GHz are fabricated in FR4 multi-layer substrate. Measured 10 dB matching bandwidth is 8 percent for single resonace antenna and 18 percent for double resonance antenna.

Study on Moonpool Resonance Effect on Motion of Modern Compact Drillship

  • Yang, Seung Ho;Yang, Young Jun;Lee, Sang Beom;Do, Jitae;Kwon, Sun Hong
    • Journal of Ocean Engineering and Technology
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    • v.27 no.3
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    • pp.53-60
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    • 2013
  • A drillship is a representative floating offshore installation. The boom in oil and gas field development has dramatically increased the demands for drillships. Drillships have a moonpool in the center area of the ship for the purpose of drilling. This moonpool has an effect on the seakeeping performance of a drillship in the vicinity of the resonance frequency. Because of the moonpool, drillships act in different resonance modes, called the sloshing mode and piston mode. The objective of this study was to find the moonpool effect on the motion of a drillship through the motion analysis of a currently operating modern compact drillship. The predicted resonance frequencies based on Molin's theoretical formula, Fukuda's empirical formula, and BEM-based numerical analysis are compared. The accuracy of the predictions using the theoretical and empirical formulas is compared with the numerical analysis and evaluated. In the case of the piston mode, the difference between the resonance frequency from theoretical formula and the resonance frequency from the numerical analysis is analyzed. The resonance frequency formula for more a complex moonpool geometry such as a moonpool with a cofferdam is necessarily emphasized.

Mode Identification in the Design of Wideband Cylindrical Monopole Antenna

  • Chun, Joong-Chang;Kim, Sang-Youl;Jeung, Deuk-Soo
    • Journal of information and communication convergence engineering
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    • v.7 no.3
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    • pp.263-267
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    • 2009
  • Cylindrical monopole antenna is one of most promising candidates for multi-band applications such as PCS, WLAN, DMB, and UWB wireless services. In this research, we demonstrate that there exist two types of current distributions according to the exciting frequency in a double band cylindrical monopole antenna, in which double resonance is achieved by adjusting the coupling structure of the antenna base. The operating modes of current distributions are identified from CST software simulations, the standing wave mode in a lower band and the traveling wave mode in a higher band. Also it is noticed that the mode behavior is quite similar to a helical antenna, a standing-wave (resonance) mode and a traveling-wave (non-resonance) mode according to the electrical dimensions of antenna. The effective ranges for operating modes and design formulas of the double band antenna are derived from simulation and measured results.

Effect of Electrodes on the Electrical Properties of Piezoelectric Ceramic Transformer (장방형 압전세라믹변압기의 전극형상이 전기적특성에 미치는 영향)

  • 정수태;최상수;조상희
    • Electrical & Electronic Materials
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    • v.10 no.6
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    • pp.562-569
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    • 1997
  • The resonance characteristics on vibration mode of a transverse type ceramic resonator and the output voltage characteristics of a piezoelectric ceramic transformer are discussed in the effects of partial electrode arrangement (one sided, centered and both sided). A resonance characteristics of resonator depended strongly on both a vibration mode and a electrode structure because of a strain distribution. The maximum resonance current of a piezoelectric ceramic transformer [PCT] with partial centered electrode appeared in λ/2 mode, and that of a PCT with partial both sided electrode appeared in 3λ/2 mode. But the maximum output voltage of those samples appeared in λ/2 mode. In the PCT with partial both sided electrode, the ration of output voltage to input current was highest out of all samples and the poling voltage was a half times of 깬두 type transformer.

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Experimental study on moonpool resonance of offshore floating structure

  • Yang, Seung-Ho;Kwon, Sun-Hong
    • International Journal of Naval Architecture and Ocean Engineering
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    • v.5 no.2
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    • pp.313-323
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    • 2013
  • Offshore floating structures have so-called moonpool in the centre area for the purpose of drilling, installation of subsea structures, recovery of Remotely-Operated Vehicle (ROV) and divers. However, this vertical opening has an effect on the operating performance of floating offshore structure in the vicinity of moonpool resonance frequency; piston mode and sloshing mode. Experimental study based on model test was carried out. Moonpool resonance of floating offshore structure on fixed condition and motion free condition were investigated. And, the effect of cofferdam which is representative inner structure inside moonpool was examined. Model test results showed that Molin's theoretical formula can predict moonpool resonance on fixed condition quite accurately. However, motion free condition has higher resonance frequency when it is compared with that of motion fixed. The installation of cofferdam moves resonance frequency to higher region and also generates secondary resonance at lower frequency. Furthermore, it was found that cofferdam was the cause of generating waves in the longitudinal direction when the vessel was in beam sea.

TEMPERATURE DEPENDENCE OF SPIN WAVE RESONANCE IN AMORPHOUS FILMS

  • Kim, Y.Y.;Baek, J.S.;Lee, S.J.;Lee, T.G.;Lim, W.Y.;Yu, S.C.;Lee, S.H.;Jang, P.W.
    • Journal of the Korean Magnetics Society
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    • v.5 no.5
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    • pp.524-527
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    • 1995
  • The temperature dependence of spin wave mode separation in amorphous $Co_{89.5}Zr_{10.5}$ thin film has been investigated at temperatures between 100 K and 300 K. The magnetization and the spectroscopic splitting factor were obtained for the main resonance mode in parallel and perpendicular magnetic field. ${\Delta}H_{2-3}$, the difference between resonance field of mode 2 and the resonance field of mode 3, increases with decreasing temperature. The linewidth increases for all the modes with decreasing temperature. Especially in mode 3 it increases rapidly below 200 K. This phenomenon could be caused by the increase of exchange stiffness constant or the decrease of surface magnetic anisotropy constant with decreasing temperature.

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Improvement of Sense Mode Bandwidth of Vibratory Silicon-On-Glass Gyroscope Using Dual-Mass System (이중 질량체를 사용한 진동형 자이로스코프의 검출부 대역폭 개선)

  • Hwang, Yong-Suk;Kim, Yong-Kweon;Ji, Chang-Hyeon
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.60 no.9
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    • pp.1733-1740
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    • 2011
  • In this research, a MEMS vibratory gyroscope with dual-mass system in the sensing mode has been proposed to increase the stability of the device using wide bandwidth. A wide flat region between the two resonance peaks of the dual-mass system removes the need for a frequency matching typically required for single mass vibratory gyroscopes. Bandwidth, mass ratio, spring constant, and frequency response of the dual-mass system have been analyzed with MATLAB and ANSYS simulation. Designed first and second peaks of sensing mode are 5,917 and 8,210Hz, respectively. Driving mode resonance frequency of 7,180Hz was located in the flat region between the two resonance peaks of the sensing mode. The device is fabricated with anodically bonded silicon-on-glass substrate. The chip size is 6mm x 6mm and the thickness of the silicon device layer is $50{\mu}m$. Despite the driving mode resonance frequency decrease of 2.8kHz and frequency shift of 176Hz from the sensing mode due to fabrication imperfections, measured driving frequency was located within the bandwidth of sensing part, which validates the utilized dual-mass concept. Measured bandwidth was 768Hz. Sensitivity calculated with measured displacement of driving and sensing parts was 22.4aF/deg/sec. Measured slope of the sensing point was 0.008dB/Hz.

3-D Vibration Characteristics of Radial Tire for Passenger Car under Fixed Axle (축으로 고정된 승용차용 레디얼 타이어의 3차원 진동특성)

  • 김용우;남진영
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.12 no.3
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    • pp.228-235
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    • 2002
  • Two kinds of experimental modal analyses have been performed on a radial tire for passenger car under fixed axle. One is the modal analysis to obtain three-dimensional modes of tire using accelerometers and the other is the one to identify cavity resonance frequency using a pressure sensor. From the first analysis, we have obtained three-dimensional natural modes and their decomposed 3-D modes in each direction, which make it possible to grasp the features of the modes that cannot be identified in the conventional 2-D modes and to classify the vibrationall modes into symmetric, non-symmetric, and antisymmetric modes in a simple way by using the experimental results. From the second experimental analysis, the cavity resonance frequency is found. Coomparing the results of the two analyses, we have Identified the three-dimensional mode of the cavity resonance. We also haute shown that natural frequencies of structural vibration depends on inflation Pressure while the cavity resonance does not.

ELASTIC WAVE RESONANCE SCATTERING FROM AN ELASTIC CYLINDER (탄성체로 인한 탄성파의 공명산란)

  • 이희남
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2003.05a
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    • pp.833-838
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    • 2003
  • The problem of elastic wave resonance scattering from elastic targets is studied in this paper. A new resonance formalism to extract the elastic resonance information of the target from scattered elastic waves is introduced. The proposed resonance formalism is an extension of the works developed for acoustic wave scattering problems by the author. The classical resonance scattering theory computes reasonable magnitude information of the resonances in each partial wave, but the phase behaves in somewhat irregular way, therefore, is not clearly explainable. The proposed method is developed to obtain physically meaningful magnitude and phase of the resonances. As an example problem, elastic wave scattering from an infinitely-long elastic cylinder was analyzed by the proposed method and compared to the results by RST. In case of no mode conversion, both methods generate identical magnitude. However, the new method computes exact $\pi$ radian phase shills through resonances and anti-resonances while RST produces physically unexplainable phases. In case of mode conversion, in addition to the phase even magnitudes are different. The phase shifts through resonances and antiresonances obtained by the proposed method are not exactly $\pi$ radians due to energy leak by mode conversion. But, the phases by the proposed method show reasonable and intuitively correct behavior compared to those by RST.

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