共查询到20条相似文献,搜索用时 31 毫秒
1.
A wideband metamaterial absorber based on a magnetic resonator loaded with lumped resistors
下载免费PDF全文
![点击此处可从《中国物理 B》网站下载免费的PDF全文](/ch/ext_images/free.gif)
<正>A wideband metamaterial absorber(MA) based on a magnetic resonator loaded with lumped resistors is presented. It is composed of a one-dimensional periodic array of double U-shaped structured magnetic resonators loaded with lumped resistors,a dielectric substrate,and a metal plate.We simulated,fabricated,measured,and analyzed the MA. The experimental results show that the reflectance(S11) is below -10 dB at normal incidence in the frequency range of 7.7 GHz-18 GHz,and the peak value is about—20 dB.Simulated power loss density distributions indicate that wideband absorption of the MA is mainly attributable to the lumped resistors in the magnetic resonator.Further investigations indicate that the distance between two unit cells along the magnetic field direction significantly influences the performance of the MA. 相似文献
2.
A. D. Lapin 《Acoustical Physics》2011,57(3):301-304
The scattering of sound by a single monopole-dipole resonator in a multimode pipe is investigated. The resonator has the form
of a Helmholtz resonator connected through a small bar to the pipe wall. In fact, this resonator is a combination of a monopole
resonator and a dipole one positioned at the same point. The scattered fields of these resonators are orthogonal to each other.
The scattering cross sections of the monopole and dipole resonators in a multimode pipe are calculated. The scattering cross
section of the monopole-dipole resonator is determined as the sum of the scattering cross sections of the monopole and the
dipole resonators. The friction in a resonator (the monopole or dipole resonator) reduces its scattering cross section by
a factor of (1 + β)2, where β is the ratio between the friction resistance and the radiation resistance of this resonator. 相似文献
3.
Photoconductive and dielectric dependence of gain and phase-shift in the coupled unidirectional photorefractive ring resonators (UPRR) have been analyzed for the case of non-degenerate two-wave mixing in photorefractive materials by employing the plane-wave approximation method. The effect of photoconductivity and dielectric constant of the coupled photorefractive crystals (A and B) on the gain and phase-shift in the coupled UPRR have also been studied in details. It has been found that for a given value of the photoconductivity of crystal B, the gain in the primary resonator can be enhanced by selecting lower value of frequency detuning of the same resonator and PR crystal A of higher photoconductivity in the coupled UPRR. But reverse of the case is found for the enhancement of phase-shift. Such enhancement of the gain and phase-shift in the primary resonator are responsible for build-up and non-reciprocal energy transfer between the modes of the internal oscillations, which greatly improves the performance of the coupled UPRR. 相似文献
4.
M. E. Il'chenko V. A. Sizranov A. A. Trubin 《Radiophysics and Quantum Electronics》1992,35(6-7):374-378
Characteristic equations and analytic expressions for the Q-factors are derived for a three-layer spherical dielectric resonator in a metal shield. The effect of dielectric coatings on the Q-factors of dielectric resonators is examined. The effect of a metal shield on thinning of the spectrum of a hollow spherical dielectric resonator is investigated.Kiev Polytechnic Institute. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 35, No. 6/7, pp. 579–586, June–July, 1992. 相似文献
5.
L. W. Zhang Y. W. Zhang L. He Z. G. Wang 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2009,55(1):155-159
Quasi-one-dimensional comb-like periodic and aperiodic structures composed
of positive index materials branch resonators and negative index materials
backbone waveguide are physically fabricated by using transmission line
approach. It is theoretically shown that the structures possess a non-Bragg
band-gap which is invariant with a change of scale length and robust against
disorder. The gap edges are determined by zero average permittivity of the
branch and the backbone and zero permeability of the backbone materials,
respectively. The transmission properties of the structures are investigated
by changing the (average) resonator size dBand the resonator spacing
dArespectively. The experimental results agree well with the
theoretical predictions and numerical simulations, which demonstrate the
independence of the special gap on the scaling and disorder in the
structures. 相似文献
6.
The dielectric tube resonator (DTR) for electron paramagnetic resonance spectroscopy is introduced. It is defined as a metallic cylindrical TE011 microwave cavity that contains a dielectric tube centered on the axis of the cylinder. Contour plots of dimensions of the metallic cylinder to achieve resonance at 9.5 GHz are shown for quartz, sapphire, and rutile tubes as a function of wall thickness and average radius. These contour plots were developed using analytical equations and confirmed by finite-element modeling. They can be used in two ways: design of the metallic cylinder for use at 9.5 GHz that incorporates a readily available tube such as a sapphire tube intended for NMR and design of a custom procured tube for optimized performance for specific sample-size constraints. The charts extend to the limiting condition where the dielectric fills the tube. However, the structure at this limit is not a dielectric resonator due to the metal wall and does not radiate. In addition, the uniform field (UF) DTR is introduced. Development of the UF resonator starting with a DTR is shown. The diameter of the tube remains constant along the cavity axis, and the diameter of the cylindrical metallic enclosure increases at the ends of the cavity to satisfy the uniform field condition. This structure has advantages over the previously developed UF TE011 resonators: higher resonator efficiency parameter Λ, convenient overall size when using sapphire tubes, and higher quality data for small samples. The DTR and UF DTR structures fill the gap between free space and dielectric resonator limits in a continuous manner. 相似文献
7.
《中国科学:物理学 力学 天文学(英文版)》2015,(11)
The characteristics of whispering gallery modes(WGM) in silver-coated inverted-wedge silica microdisks are theoretically investigated by using finite element method. Dielectric TE mode always exists in silver-coated inverted-wedge resonators; dielectric TM mode tends to couple with SPP modes; only pure interior surface plasmonic polariton(SPP) mode but not pure exterior SPP mode is observed in contrast to the metal-coated cylindrical and toroidal resonators. The dependence of quality factor of different kinds of WGMs on the radius of the resonator and the thickness of the coated silver layer are systematically analyzed. We find that the quality factors of the hybrid WGMs associated with SPP mode can reach 104. The maximum light intensity enhancement in ambient for a hybrid mode consisting of a dielectric TM mode and an exterior SPP mode can be obtained when a silver film of thickness ~40 nm is deposited. The silver-coated inverted-wedge silica resonators may be widely applied in sensing and surface enhanced Raman scattering. 相似文献
8.
Czechowski T Krzyminiewski R Jurga J Chlewicki W 《Journal of magnetic resonance (San Diego, Calif. : 1997)》2008,195(1):52-59
New EPR resonators were developed by using a ceramic material with a high dielectric constant, epsilon=160. The resonators have a high quality factor, Q=10(3), and enhance the sensitivity of an EPR spectrometer up to 170 times. Some advantages of the new ceramic resonators are: (1) cheaper synthesis and simplified fabricating technology; (2) wider temperature range; and (3) ease of use. The ceramic material is produced with a titanate of complex oxides of rare-earth and alkaline metals, and has a perovskite type structure. The resonators were tested with X-band EPR spectrometers with cylindrical (TE(011)) and rectangular (TE(102)) cavities at 300 and 77K. We discovered that EPR signal strength enhancement depends on the dielectric constant of the material, resonator geometry and the size of the sample. Also, an unusual resonant mode was found in the dielectric resonator-metallic cavity structure. In this mode, the directions of microwave magnetic fields of the coupled resonators are opposite and the resonant frequency of the structure is higher than the frequency of empty metallic cavity. 相似文献
9.
10.
In this paper, we report the design, simulation, and measurements of a broadband metamaterial absorber (MA) based on a periodic array of multi-layer cross-structure resonators. A perfect narrowband MA consists of cross-structure resonator, dielectric substrate, and continuous metal films, and the absorption frequency can be tunable by changing the geometrical parameters based on L-C resonance circuit theory. Furthermore, the absorption band of our design is effectively extended by simply stacking several such structural layers with different geometrical dimensions. Finally, the 4-layer cross-structure MA is only 2 mm, which can achieve a full width at half maximum (FWHM) bandwidth of 2 GHz by numerical simulations, and 90 % bandwidth of 1.9 GHz by experiments. 相似文献
11.
AbstractSurface-enhanced Raman scattering (SERS) has attracted great interest due to its remarkable enhancement, excellent sensitivity, and the “fingerprinting” ability to produce distinct spectra for detecting various molecules. Noble metal nanomaterials have usually been employed as SERS-active substrates because of their strong SERS enhancement originated from their unique surface plasmon resonance (SPR) properties. Because the SPR property depends on metal material's size, shape, morphology, arrangement, and dielectric environment around metal nanostructures, the key to wider applications of SERS technique is to develop plasmon-resonant structures with novel geometries to enhance Raman signals and to control the periodic ordering of these structures over a large area to obtain reproducible Raman enhancement. This review presents a general view on the theory background of SERS effect and several basic concepts and focuses on recent progress in engineering metallic nanostructures with various morphologies using versatile methods for improving SERS properties. Their potential applications in the field of chemical detection and biological sensing are overviewed. 相似文献
12.
The dependence of the enhancement of the Raman scattering on the size of a dielectric column is measured in structures with the spatial modulation of the height and lateral sizes of the dielectric coated with a thick metal layer (10–80 nm). It is established that, in the case of a thick metal coating (silver, gold, and copper coatings are used) at dimensions of the dielectric column close to the laser pump wavelength, considerable enhancement of the Raman signal oscillating upon the variation of the geometrical dimensions of the structure is observed. It is shown that the observed resonance enhancement of the Raman signal is associated with the transformation of the electromagnetic radiation into localized plasmon–polariton modes, and the efficiency of such transformation is determined by the commensurability of the wavelength of the plasmon–polariton mode and the planar size of the metal film. For different metal coatings, the dependence of the enhancement of the Raman scattering on the laser wavelength is measured. 相似文献
13.
Ivan S. Grudinin Andrey B. Matsko Anatoliy A. Savchenkov Dmitry Strekalov Vladimir S. Ilchenko Lute Maleki 《Optics Communications》2006,265(1):33-38
We report on the fabrication technique of ultra high Q optical crystalline whispering gallery mode microresonators and discuss their properties. The technique is suitable for the majority of available optical crystals and for production of resonators with small size. To validate the method, we made CaF2 resonators with Q factors exceeding 4 × 108 and a diameter smaller than 100 μm. A single mode resonator has also been fabricated. Possible utilization of these new resonators in quantum optics is discussed. 相似文献
14.
M. V. Zhuravlev 《Radiophysics and Quantum Electronics》2009,52(2):157-164
We study the threshold conditions of the parametric excitation of temperature oscillations using pulsed microwave pumping
in three-mode regime for high-Q ferroelectric cryogenic resonators made of SrTiO3 and KTaO3. Comparative analysis is performed for the threshold power of the excitation of temperature oscillations and the threshold
power of the ponderomotive parametric excitation of acoustic oscillations in the resonator. It is shown that in three-mode
regime, temperature oscillations can develop under a rather moderate pump power of about 0.1–8 μW, depending on the combination of interacting temperature and electromagnetic modes. The calculated low threshold powers
allow one to apply resonators in practice as high-sensitivity infrared sensors, resonant bolometers, and parametric amplifiers.
Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 52, No. 2, pp. 172–180, February 2009. 相似文献
15.
《Infrared physics》1987,27(4):233-240
The efficient excitation of coherent THz phonons requires an electric field as high as possible at the surface of the piezoelectric transducer material. This can be done below 1011Hz by means of a coaxial resonator or a cavity resonator, respectively. At still higher frequencies new kinds of suitable resonators must be developed. In this paper two types of low-mode submillimeterwave resonators, a dielectric waveguide resonator and a two-layer Fabry-Perot resonator, are investigated with respect to their electromagnetic properties in the THz range. 相似文献
16.
用微扰法研究了两端接地型蓝宝石介质谐振器测量高温超导薄膜微波表面电阻RS的误差与几何结构和工作频率的关系.结果表明,介质柱直径与高度之比2a/L,金属屏蔽腔内半径与介质柱半径之比b/a以及工作频率f对测量误差和最小可测表面电阻Rsmin有很大影响.所得到的曲线可用于蓝宝石介质谐振器的设计中.结果还表明,适当选取2a/L,b/a与f可使测量误差接近于1%,最小可测表面电阻Rsmin可达到微欧姆的数量级.这对于高温超导薄膜的检测和微波器件应用说
关键词:
介质谐振器
高温超导薄膜
微波表面电阻
误差分析 相似文献
17.
Wangchang Li Xiaojing Qiao Yang Luo F. X. Qin H. X. Peng 《Applied Physics A: Materials Science & Processing》2014,115(1):229-234
In this paper, we present a design, simulation and experimental measurement of a metamaterial absorber (MMA) in the microwave regime. The proposed MMA structure consists of periodic cross electric resonators separated from the ground metal plane using a magnetic composite layer. The broadband absorption can be ascribed to the periodic cross electric resonators. The anti-parallel currents are observed at the peak frequency on the surface of the MMA and the ground metal plane, respectively, and thus the coupled resonance magnetic field occurs in the magnetic medium resulting in the magnetic loss. The new absorption peak located at 2.8 GHz broadens the whole absorption spectrum. The frequency of this peck is lower than that of the cross resonator of 3.7 GHz, suggesting the distinguish resonance mechanism: the absorbing properties are ascribed to the phase cancellation, Ohmic loss, dielectric loss at the end of the cross pattern, and the magnetic loss caused by the above mentioned coupled magnetic field. The obvious absorption peak at 2.8 GHz is also observed experimentally verifying the simulation result. All these results indicate the proposed MMA structure is promising for microwave absorbing application. 相似文献
18.
We demonstrate strongly nondegenerate optical continuous-wave parametric oscillations in crystalline whispering gallery mode resonators fabricated from LiNbO3. The required phase matching is achieved by geometrical confinement of the modes in the resonator. 相似文献
19.
Simulation of dielectric resonator for high-Tc radio frequency superconducting quantum interference device
下载免费PDF全文
![点击此处可从《中国物理 B》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Nowadays, the high-critical-temperature radio frequency
superconducting quantum interference device (high-$T_{\rm c }$ rf
SQUID) is usually coupled to a dielectric resonator that is a
standard $10\times 10\times 1$~mm3 SrTiO$3 (STO) substrate
with a YBa2Cu$3O$_{7 - \delta }$ (YBCO) thin-film flux
focuser deposited on it. Recently, we have simulated a dielectric
resonator for the high-$T_{\rm c }$ rf SQUID by using the ANSOFT High
Frequency Structure Simulator (ANSOFT HFSS). We simulate the
resonant frequency and the quality factor of our dielectric
resonator when it is unloaded or matches a 50-$\Omega$ impedance.
The simulation results are quite close to the practical
measurements. Our study shows that ANSOFT HFSS is quite suitable for
simulating the dielectric resonator used for the high-$Tc rf
SQUID. Therefore, we think the ANSOFT HFSS can be very helpful
for investigating the characteristics of dielectric resonators for
high-$Tc rf SQUIDs. 相似文献
20.
We consider the equations of interaction between electromagnetic oscillations and the temperature in a nonlinear dielectric
resonator. The conditions for emergence of the oscillatory instability in the system are analyzed. The threshold conditions
(power and automodulation frequency) of electrothermal excitation are calculated for microwave virtual-ferroelectric resonators
for the simplest case of two-mode interaction. The dielectric nonlinearity is shown to impose limitations on the feasibility
of electrothermal excitation.
Physical Faculty, M. V. Lomonosov Moscow State University, Moscow, Russia. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii,
Radiofizika, Vol. 43, No. 2, pp. 162–173, September 2000. 相似文献