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Damping has an important influence on the vibro-acoustic performance of locally resonant metamaterials, broadening the frequency range of attenuation at the expense of peak performance. This paper discusses the influence of damping on the dispersion curves of a locally resonant metamaterial. Unit cell analysis is applied and solved using both an inverse and a direct approach, leading to respectively...
This work presents a three-dimensional, single phase, elastic periodic structure endowed with a complete bandgap at low frequency regime generated by a distributed set of local resonators. The behaviours of the unit cell and of the finite structure are studied numerically. A prototype of the finite structure is fabricated by means of Selective Laser Sintering technique and it is tested to assess the...
Metabarriers of surface resonant structures can redirect seismic Rayleigh waves into the soil bulk reducing the surface ground motion. Here we investigate multi-mass meta-barriers able to open multiple band gaps in the low frequency range [1-20] Hz and target known resonance frequencies of buildings and infrastructures.
This work presents novel approaches for designing labyrinthine acoustic meta-materials with extreme and/or tunable dispersion characteristics. The first approach is inspired by fractal-type plane-filling curves, the use of which allows extending the labyrinthine wave paths to maximum possible lengths. The second approach harnesses the biological structures, e.g. spider-web architecture, to achieve...
We propose a model of a piezoelectric power harvester that scavenges energy from the cavity of a phononic crystal (PnC). The band structure of the PnC with a cavity is calculated by super-cell technique. The energy is collected in the cavity when the frequency of the cavity defect mode appears inside the band gap. As a result, the harvester can transform mechanical energy into electric energy efficiently.
We investigate theoretically and numerically the transport of light in a three-dimensional (3D) crystal of cavities inside a 3D inverse woodpile photonic crystal. This class of crystals consists of two perpendicular arrays of pores and has a very broad 3D photonic band gap. An individual point defect is formed by reducing the radius of two intersecting pores. An earlier study revealed that an isolated...
This digest paper reports on the first demonstration of suspended β-Ga2O3 nanostructures and nanomechanical resonators made from single-crystal β-Ga2O3 nanosheets or nanomembranes grown via low pressure chemical vapor deposition (LPCVD) on 3C-SiC epi-layer on Si substrate. These single-crystal β-Ga2O3 drumhead nanomechanical resonators offer robust multimode resonances at frequencies in the range...
This paper present different design methods to improve the performance of MPA. A comparative analysis of EBG and DGS structures in terms of performance has been given. The proposed DGS structure improves gain, efficiency and the return loss of the antenna. The antenna w/o EBG and DGS resonates at 2.4 GHz offering bandwidth of 67.8 MHz. Three different types of DGS structure have been designed and...
The artificial plasmon-polariton bandgaps were studied and manipulated at infrared frequencies. The polaritons were facilitated by manifesting the strongly coupled states among electromagnetic wave and the induced electric dipoles in two-dimensional (2D) indium-tin-oxide nanorod arrays (ITO-NRAs).
Additively manufactured 3D phononic crystals have demonstrated wide acoustic band gaps and strong acoustic mode suppression not attainable by corresponding 2D designs. In this work we present the combination of these air-filled 3D structures with an enclosed fluidic cavity resonator in a single printed sensor element for the first time. This combination drastically improves the sensitivity of the...
This work is focused on the application of Phononic Crystals to reduce anchor losses of MEMS contour mode resonators. Anchor losses dominates the losses in these type of released resonators at low frequency and at low temperature. The use of phononic crystals, intended as finite-periodic distribution of holes in the anchor, is fully compatible with fabrication processes and moreover it is easy to...
We propose to use arrays of resonant structures buried around sensitive locations as protection against surface seismic waves. The resonant structures consist of concrete tubes containing a steel mass suspended by soft bearings. We verify their design numerically and on a scaled experimental campaign. The arrays attenuate and redirect Rayleigh waves within the [1–10Hz] frequency range.
A method of antenna element coupling control using a readjust of the surface impedance of the plane, it is mounted, is shortly described. A construction of a tunable frequency-selective metamaterial-made surface, which is designed to be a patch antenna element ground plane, is presented. Results of antenna VSWR measurements, which show the coupling change correspondingly the antenna ground plane surface...
By combining concepts from elasticity, photonics and metamaterials, we present a seismic metasurface capable to convert or reflect seismic Rayleigh waves propagating in a sedimentary ground. The metasurface is obtained with an array of trees, with their height gradually decreasing to form a wedge-like profile, “the metawedge”. Local resonance phenomena between trees and ground, combined with the spatially...
In this work, we study the terahertz multichannel filtering properties based on a stage 3 triadic-Cantor-set semiconductor photonic crystal. Here, we use the semiconductor of n-InSb so that transmission responses have three regions. Two regions with frequencies well above and below the resonant frequency, the permittivity functions are nearly a positive constant. In these two regions, transmittance...
Electromagnetic band gap (EBG) is widely used to suppress the transportation of simultaneous switching noise (SSN) in circuit. But the periodic High impedance planes of EBG destroy the return path of signal line. That phenomenon leads serious problem of signal integrity, which makes the research of EBG more important. In this paper, a new structure of EBG with multi-via and double-layer structure...
This work considers the use of multi-defect Photonic Band Gap (PBG) structures to form a novel multi-beam Klystron. A photonic crystal (PC) is a periodic arrangement of media with different refractive indices to form a lattice. Electromagnetic (EM) waves at certain frequencies can propagate through this lattice, but at other frequencies they cannot. The frequency regions where the wave can propagate...
This paper proposes the design of a multiband absorber using EBG structures to absorb radiation in the X-band for stealth applications. It can also be used in the K and Ka bands for reduction of Electromagnetic Interference. The structure was created using Genetic Algorithm and the simulation was performed on Ansoft High Frequency Surface Solver (HFSS). The results indicate that the structure has...
In this paper, a compact electromagnetic bandgap (EBG) structure is presented. In order to achieve the size reduction, additional equivalent capacitance and equivalent inductance are produced in three design steps. The total capacitance and inductance of the proposed structure will be increased much more than the one of the mushroom-like EBG in the literature. Dispersion diagram is presented to show...
We investigate the resonant enhancement of transmission and reflection of a plane electromagnetic wave incident on a multilayer three-dimensional fully dielectric photonic crystal in which a defect layer with excited medium inclusions has been designed specifically to obtain a high-density mode. The numerical investigation is performed for a near infrared wavelength range. Comparison of transmission...
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