• 한국정보전자통신기술학회논문지
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• 제9권6호
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• pp.630-636
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• 2016

In this paper, a novel triple-mode cavity structure, designed for compactness and operating at 850 MHz, is analyzed. A cylindrical dielectric resonator is loaded into a metallic cylindrical cavity. Previous study has been focused on the analysis of the cylindrical dielectric resonator, but in this paper, the effect of the cylindrical metallic cavity has been analyzed. Enclosing the dielectric resonator inside the metallic cavity increases the resonant frequency of the dielectric resonator; however, this increases the quality factor and introduces the possibility of installing coupling screws. The principle of generation of triple-mode was investigated by parametric analysis. The generated triple-mode is TE011 mode and two orthogonally generated HEM121 modes. By adjusting the radius of the dielectric resonator, the height of the dielectric resonator, or the radius of the cylindrical metallic cavity, three modes could be coincided. However, the height of the metallic cavity keeps three modes separated. The mode characteristics of the proposed cavity are analyzed using a full-wave electromagnetic (EM) simulation. The proposed triple-mode cavity could be developed to triple-mode filter using a coupling screw, and the commercial application for the miniaturized filter below 1 GHz could be expected.

• Journal of Multimedia Information System
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• 제5권2호
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• pp.143-146
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• 2018

The eigen value problem of a coaxial cavity and a modified pill box cavity is investigated using the mode matching technique. The coaxial cavity has a cylindrical cavity with beam ports and center conductor. The pill box cavity is the same as a coaxial cavity without center conductor. The electric field and magnetic field are formulated in propagation region and resonance region. The boundary and orthogonal conditions are applied to the electric and magnetic fields. We derived the eigen value equation by the proposed procedure in a coaxial cavity and a modified pill box cavity. The electromagnetic field of the real structure is disturbed by the coaxial wire. The effect of the coaxial wire in pill box cavity with beam ports increase the dominant resonant frequency. The coaxial line method of the coupling impedance is not adequate for a cylindrical cavity. The results of the mode matching technique and simulation agree well. The results confirm the proposed formulation is valid.

• 대한전자공학회논문지TC
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• 제38권11호
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• pp.55-62
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• 2001

2차원 open cylindrical cavity의 전자파 투과 및 산란특성에 대해 연구하였다. 이러한 구조는 cavity 및 aperture의 크기에 따라 전파의 투과나 산란특성에 특이한 현상이 나타남에도 불구하고 정확한 분석이 이루어지지 않았다. 본 논문에서는 모멘트법의 확장형인 FMM 기법을 이용하여 비교적 광범위하게 open cavity의 특성을 계산하였다. 계산결과 open cylindrical cavity의 경우 closed cavity의 internal mode에 대응하는 external mode가 존재하고, 이때 공진 및 산란특성은 비공진시와 다른 특성을 나타냄을 확인하였다. 연구결과는 전자파의 차폐 및 RCS 통제분야에 응용할 예정이다.

• Journal of electromagnetic engineering and science
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• 제4권1호
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• pp.30-36
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• 2004

We determined equivalent circuit parameters of a 1.5 cell S-band RF gun cavity from the resonant characteristics of its decoupled cavities(half cell and full cell) using the code SUPERFISH. Equivalent circuit parameters of the 1.5 cell RF gun cavity resonated in the 0-mode were obtained easily from the circuit parameters of each decoupled cavities. In order to obtain equivalent circuit parameters for the $\pi$ -mode cavity, we calculated the differences of the resonant frequencies and the equivalent resistances between the 0- and $\pi$ -modes with slight variations of the radius and thickness of the coupling iris. From those differences, we obtained R/Q value and equivalent resistance of the $\pi$ -mode, which are directly related to the equivalent circuit parameters of the coupled cavity. Using calculated R/Q value, we can express equivalent inductance, capacitance and resistances of the RF gun cavity resonated in the $\pi$ -mode, which can be useful for analyzing coupled cavities in a steady state.

• 한국통신학회논문지
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• 제22권6호
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• pp.1251-1258
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• 1997

Generally, it is very important to study selective coupling between cavities of the filter structure using multimode cavity resonator. In this paper, we have manufactured 5-pole bandpass filter(BPF) using dual and triple-mode cavity resonator. To do so, we have derived the formulas for coupling coefficient about coupling between TE-modes from TM/TE-mode's tangential and lognitudinal field intensities each other. To implement the Chebyshev response, the intercabity slot combining dual-mode and triple-mode is designed to couple one H-field of TE-mode parallel to slot plate. In this paper, specially it is derived the formulas for T $E_{11p}$-mode from TE-modes, and determined after obtaining location and size of intercabity slot from the equation. In this ppaer, based on this result, we designed and implmented teh bandpass filter operated at the center frequency of 14.5GHz with a Chebyshev response. For the manufactured cavity filter, dual-mode and triple-mode cavity are resonted by two orthogonal T $E_{113}$-modes, and by two orthogonal T $E_{113}$-modes and one T $M_{012}$-mode, respecitively. The 2-stage 5-pole BPF proposed in this paper has the insertion loss of -2.32dB, the reflection loss of -15dB in the passband, and the out-or-rejection of -67dB.

• Advances in aircraft and spacecraft science
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• 제3권3호
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• pp.351-366
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• 2016

Macroperforations improve the sound absorption performance of porous materials in acoustic cavities and in waveguides. In an acoustic cavity, enhanced noise reduction is achieved using porous materials having macroperforations. Double porosity materials are obtained by filling these macroperforations with different poroelastic materials having distinct physical properties. The locations of macroperforations in porous layers can be chosen based on cavity mode shapes. In this paper, the effect of variation of macroporosity and double porosity in porous materials on noise reduction in an acoustic cavity is presented. This analysis is done keeping each perforation size constant. Macroporosity of a porous material is the fraction of area covered by macro holes over the entire porous layer. The number of macroperforations decides macroporosity value. The system under investigation is an acoustic cavity having a layer of poroelastic material rigidly attached on one side and excited by an internal point source. The overall sound pressure level (SPL) inside the cavity coupled with porous layer is calculated using mixed displacement-pressure finite element formulation based on Biot-Allard theory. A 32 node, cubic polynomial brick element is used for discretization of both the cavity and the porous layer. The overall SPL in the cavity lined with porous layer is calculated for various macroporosities ranging from 0.05 to 0.4. The results show that variation in macroporosity of the porous layer affects the overall SPL inside the cavity. This variation in macroporosity is based on the cavity mode shapes. The optimum range of macroporosities in poroelastic layer is determined from this analysis. Next, SPL is calculated considering periodic and nodal line based optimum macroporosity. The corresponding results show that locations of macroperforations based on mode shapes of the acoustic cavity yield better noise reduction compared to those based on nodal lines or periodic macroperforations in poroelastic material layer. Finally, the effectiveness of double porosity materials in terms of overall sound pressure level, compared to equivolume double layer poroelastic materials is investigated; for this the double porosity material is obtained by filling the macroperforations based on mode shapes of the acoustic cavity.

• 전기의세계
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• 제28권4호
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• pp.47-52
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• 1979

Total number of resonant modes in a microwave oven cavity may be maximized for a given frequency bandwidth to obtain more uniform power distribution by choosing proper size of the cavity. The total number of modes is calculated for a dielectrically loaded rectangular cavity and its size is suggested here for which the change in the number of modes is less sensitive to the change of dielectric layer thickness and its total number of modes is maximized in a given range of cavity sizes. A prove coupled rectangular cavity is constructed and the total existing modes are measured to see the change of modes depending on the dielectric layer thickness and the cavity size. Surface wave mode existing in the dielectric layer is confirmed by measuring Q and the input impedance of the cavity for this mode, which closely compares with the calculation.

• 한국음향학회:학술대회논문집
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• 한국음향학회 1993년도 학술논문발표회 논문집 제12권 1호
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• pp.17-20
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• 1993

The acoustic mode of a perforated tube muffler was investigated both theoretically and experimentally to explain the cavity-tones induced by through-flow. The cutoff frequencies for the axisymmetric modes were obtained and confirmed experimentally. It was found that the cutoff frequencies are decreased significantly by the perforated tube. The onset frequencies of the cavity-tones were compared with the cutoff frequencies of the acoustic mode and it was found that the cavity-tones are induced by the radial acoustic modes and their frequency stages are coincident with the discrete cutoff frequencies.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2001년도 하계학술대회 논문집
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• pp.1069-1072
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• 2001

We described a method resonant mode identification in dielectric-rod loaded cylindrical cavity resonators. Resonant frequency of dielectric loaded cavity is calculated by analyzing the characteristic equation. The characteristic equation is solved by using the ContourPlot graph of Mathematica. As the result of comparing calculation value and experimental value of resonant frequencies, we know that the field representation of non-decaying mode is exact. The contour graph method is not a method using approximated representation of electromagnetic field variation at the outer area of dielectric in the resonators but a method using exact representation.

• Progress in Superconductivity
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• 제1권1호
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• pp.36-41
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• 1999

Methods for mode identification and accurate measurements of the unloaded Q ($Q_0$) of a dielectric-loaded $TE_{01{\delta}}$ mode cavity resonator with HTS endplates are proposed. A resonator with a sapphire rod and $YBa_2Cu_3O_{7-x}$(YBCO) endplates was prepared and its microwave properties were studied at temperatures above 30 K. The $TE_{01{\delta}}$ mode $Q_0$ of the resonator, designed to work as a tunable resonator with variations in the gap distance (s) between the sapphire rod and the top YBCO, was more than 1000000 at s = 0 mm and at 30 K with the resonant frequency of 19.56 GHz. The $TE_{01{\delta}}$ mode $Q_0$ decreases as s increases for s < 2 mm until mode couplings between the $TE_{01{\delta}}$ mode and other modes appeared at s = 2 mm. Significant dependence of the $TE_{01{\delta}}$ mode $Q_0$ on the input and output coupling constants was also observed. Applications of the open-ended $TE_{01{\delta}}$ mode cavity resonator for a tunable resonator with a very high Q as well as a characterization tool for the surface resistance measurements of HTS films are described.