Band gap characterization of complex unit cell geometries for 3D phononic crystals

Phononic band gap crystals (PnCs) are periodic composite materials and well known for their novel property that can prohibit the propagation of mechanical waves in certain range of frequency. This paper develops the finite element method to calculate band structures of bi-material phononic crystals. Through finite element analysis, complete band gap for longitudinal and transverse waves are obtained by characterizing the dispersion relation in phononic crystals. Phononic crystals with different inclusion shapes in a square and hexagonal unit cell are investigated to study the influence of unit cell topology on band gap size. For a specific pattern, the existence of complete band gap in relation to the density and Lamé constant modulus of composites is studied and critical density ratio and Lamé constant ratio of inclusions versus base material for opening complete band gap are given. The results provide theoretical guidance for designing phononic crystals in practical applications.

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A miniaturized dual band EBG unit cell for UWB antennas with high selective notching

International Journal of Microwave and Wireless Technologies ◽

10.1017/s1759078719000710 ◽

2019 ◽

Vol 11 (10) ◽

pp. 1035-1043 ◽

Cited By ~ 1

Author(s):

Mahmoud A. Abdalla ◽

Abdullah A. Al-Mohamadi ◽

Ibrahim S. Mohamed

Keyword(s):

Band Gap ◽

Unit Cell ◽

Ultra Wideband ◽

Dual Band ◽

Circuit Modeling ◽

Electromagnetic Band Gap ◽

Uwb Antennas ◽

Antenna Performance ◽

Full Wave

AbstractA high selective dual band and miniaturized electromagnetic band gap (EBG) unit cell is presented in this paper. The analysis and characterization of the new cell are explained. The modified compact EBG unit cell is based on cutting two inverted U-shaped slots inside the typical mushroom-like EBG. The modified EBG has a 70% size reduction. The dual-band functionality of the structure is confirmed by applying it in a dual-notch ultra-wideband antenna (3.1–10.6 GHz), and the notch frequencies are 5.2 and 5.8 GHz. The dual-band functionality has advantages of a highly selective bandpass between them. The antenna can suppress interference frequencies in less than 100 MHz bandwidth without affecting the antenna performance in the whole bandwidth. Presented results are addressed in terms of circuit modeling, 3D full-wave simulations, and measurements.

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Analysis of Periodicity Termination in Phononic Crystals

Volume 8: Mechanics of Solids, Structures and Fluids; Vibration, Acoustics and Wave Propagation ◽

10.1115/imece2011-65666 ◽

2011 ◽

Cited By ~ 4

Author(s):

Bruce L. Davis ◽

Andrew S. Tomchek ◽

Edgar A. Flores ◽

Liao Liu ◽

Mahmoud I. Hussein

Keyword(s):

Band Gap ◽

Timoshenko Beam ◽

Periodic Structures ◽

Beam Theory ◽

Phononic Crystals ◽

Timoshenko Beam Theory ◽

Band Gaps ◽

Pass Band ◽

Unit Cells

While resonant propagation modes are non-existent within band gaps in infinite periodic structures, it is possible for anomalous band-gap resonances to appear in finite periodic structures. We establish two criteria for the characterization of band-gap resonances and propose approaches for their elimination. By considering flexural periodic beams, we show that as the number of unit-cells is increased the vibration response corresponding to band-gap resonances (1) does not shift in frequency, and (2) drops in amplitude. Both these outcomes are not exhibited by regular pass-band resonances, nor by resonances in finite homogenous beams when the length is changed. Our conclusions stem from predictions based on Timoshenko beam theory coupled with matching experimental observations.

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Preparation and Characterization of Polyvinylidene Fluoride/ZrO2-TiO2 Optical Film with Wide Band Gap and High Refractive Index

Journal of Inorganic Materials ◽

10.3724/sp.j.1077.2013.12747 ◽

2013 ◽

Vol 28 (6) ◽

pp. 671-676 ◽

Cited By ~ 4

Author(s):

Yu-Qing ZHANG ◽

Li-Li ZHAO ◽

Shi-Long XU ◽

Chao ZHANG ◽

Xiao-Ying CHEN ◽

...

Keyword(s):

Refractive Index ◽

Band Gap ◽

Polyvinylidene Fluoride ◽

Wide Band ◽

High Refractive Index ◽

Wide Band Gap ◽

Optical Film

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Characterization of Tiled Architecture for C-Band 1-Bit Beam-Steering Transmitarray

Sensors ◽

10.3390/s21041259 ◽

2021 ◽

Vol 21 (4) ◽

pp. 1259

Author(s):

Dmitry Kozlov ◽

Irina Munina ◽

Pavel Turalchuk ◽

Vitalii Kirillov ◽

Alexey Shitvov ◽

...

Keyword(s):

Communication Systems ◽

Beam Steering ◽

Unit Cell ◽

Electromagnetic Simulations ◽

Fifth Generation ◽

Full Wave ◽

Array Architecture ◽

Modulation Pattern ◽

Good Agreement

A new implementation of a beam-steering transmitarray is proposed based on the tiled array architecture. Each pixel of the transmitarray is manufactured as a standalone unit which can be hard-wired for specific transmission characteristics. A set of complementary units, providing reciprocal phase-shifts, can be assembled in a prescribed spatial phase-modulation pattern to perform beam steering and beam forming in a broad spatial range. A compact circuit model of the tiled unit cell is proposed and characterized with full-wave electromagnetic simulations. Waveguide measurements of a prototype unit cell have been carried out. A design example of a tiled 10 × 10-element 1-bit beam-steering transmitarray is presented and its performance benchmarked against the conventional single-panel, i.e., unibody, counterpart. Prototypes of the tiled and single-panel C-band transmitarrays have been fabricated and tested, demonstrating their close performance, good agreement with simulations and a weak effect of fabrication tolerances. The proposed transmitarray antenna configuration has great potential for fifth-generation (5G) communication systems.

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Band-Gap Tuning in Two-Dimensional Spatiotemporal Phononic Crystals

Physical Review Applied ◽

10.1103/physrevapplied.15.014022 ◽

2021 ◽

Vol 15 (1) ◽

Author(s):

D. Psiachos ◽

M.M. Sigalas

Keyword(s):

Band Gap ◽

Phononic Crystals ◽

Two Dimensional ◽

Band Gap Tuning

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Structural and computational investigation of an imine-based propeller-shaped macrocyclic cage

SN Applied Sciences ◽

10.1007/s42452-021-04255-7 ◽

2021 ◽

Vol 3 (2) ◽

Author(s):

Sriram Srinivasa Raghvan ◽

Suresh Madhu ◽

Velmurugan Devadasan ◽

Gunasekaran Krishnasamy

Keyword(s):

Band Gap ◽

Density Functional ◽

Strain Tensor ◽

Strong Interactions ◽

Soft Condensed Matter ◽

Functional Theory ◽

Self Assembling ◽

Phenyl Rings ◽

Crystal Volume

AbstractIn this study, we present the synthesis, spectroscopic and structural characterization of self-assembling gem-dimethyl imine based molecular cage (IMC). Self-assembling macrocycles and cages have well-defined cavities and have extensive functionalities ranging from energy storage, liquid crystals, and catalysts to water splitting photo absorber. IMC has large voids i.e., 25% of the total crystal volume thus could accommodate wide substrates. The synthesized imine-based molecular cages are stabilized by coaxial π bonded networks and long-range periodic van der Waal and non-bonded contacts as observed from the crystal structure. IMC also has typical properties of soft condensed matter materials, hence theoretical prediction of stress and strain tensor along with thermophysical properties were computed on crystal system and were found to be stable. Molecular dynamics revealed IMC is stabilized by, strong interactions between the interstitial phenyl rings. Density functional theory (DFT) based physicochemical properties were evaluated and has band gap of around 2.38ev (520 nm) similar to various photocatalytic band gap materials.

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