scholarly journals UHF Metamaterial Absorber with Small-Size Unit Cell by Combining Fractal and Coupling Lines

2018 ◽  
Vol 2018 ◽  
pp. 1-9 ◽  
Author(s):  
Shicheng Fan ◽  
Yaoliang Song
Keyword(s):  
Design Principle ◽  
Metal Structure ◽  
Resonance Wavelength ◽  
Dielectric Substrate ◽  
Metamaterial Absorber ◽  
Unit Cell ◽  
Absorption Mechanism ◽  
Small Unit ◽  
Small Ratio ◽  
Surface Metal

We present a perfect UHF metamaterial absorber by combining coupling lines and fractal lines with a very small unit cell. The proposed absorber consists of a surface metal structure and metallic background plane, separated by a dielectric substrate and air. Simulation results show that the absorber has an absorption peak at 442 MHz with 99.73% absorptivity. The ratio between a lattice constant and resonance wavelength is 1/68, significantly less than the existing absorber. The design principle is introduced in detail according to the absorption mechanism of the proposed absorber. Moreover, the absorption peaks remain high with large angles of incidence for both TE and TM polarizations. Due to the small ratio, it can be widely used in radiation suppression for microwave relay communication such as mobile communication and wireless network by changing the parameters of the structure.

scholarly journals Planar Dual Polarized Metasurface Array for Microwave Energy Harvesting

Electronics ◽  
2020 ◽  
Vol 9 (12) ◽  
pp. 1985
Author(s):  
Maged A. Aldhaeebi ◽  
Thamer S. Almoneef
Keyword(s):  
Energy Harvesting ◽  
Dielectric Substrate ◽  
Metamaterial Absorber ◽  
Absorption Efficiency ◽  
Unit Cell ◽  
Resistive Load ◽  
Electromagnetic Energy Harvesting ◽  
Absorbed Power ◽  
Simulation Results ◽  
Dual Polarized

The design of a dual polarized metasurface collector based on the metamaterial full absorption concept for electromagnetic energy harvesting is introduced. Unlike previous metamaterial absorber designs, here the power absorbed is mostly dissipated across a resistive load rather than within the dielectric substrate. This is achieved by channeling the absorbed power to an optimal resistive load through a via hole. The simulation results show that a power absorption efficiency of 98% is achieved at an operating frequency of 2 GHz for a single unit cell. A super unit cell consisting of four cells with alternating vias was also designed to produce a dual polarized metasurface. The simulation results yielded a radiation to AC efficiency of around 98% for each polarization.

scholarly journals A Switchable Ultra-Wideband Metamaterial Absorber with Polarization-Insensitivity and Wide-incident Angle at THz Band

2021 ◽  
Vol 8 ◽  
Author(s):  
Liansheng Wang ◽  
Dongyan Xia ◽  
Quanhong Fu ◽  
Xueyong Ding ◽  
Yuan Wang
Keyword(s):  
Incident Angle ◽  
Ground Plane ◽  
Surface Current ◽  
Dielectric Substrate ◽  
Metamaterial Absorber ◽  
Ultra Wideband ◽  
Absorption Mechanism ◽  
Te Mode ◽  
Polarization Insensitivity ◽  
High Absorption

In this paper, we report a switchable ultra-wideband metamaterial absorber with polarization-insensitivity and wide-incident angle at THz band which is composed of VO2 disk, polyimide dielectric substrate, and gold ground plane. The results show that the absorption is greater than 90% from 3.5–8 THz for a temperature of 300 K and this absorption band disappears when the temperature rises to 350 K. The absorption property of our proposed metamaterial absorber is insensitive to polarization states and angles and it can withhold high absorption of more than 80% for wide-incident angles, up to 60° for TE mode and TM mode. The wideband absorption mechanism is elucidated using an effective medium and surface current analysis.

scholarly journals A Broadband Metamaterial Absorber

2019 ◽  
Vol 8 (6S4) ◽  
pp. 116-118
Keyword(s):  
Ground Plane ◽  
Dielectric Substrate ◽  
Metamaterial Absorber ◽  
Unit Cell ◽  
Five Dimensions

This paper gives structure and standard execution of a broadband metamaterial protect at microwave frequencies.The unit cell of proposed structure combines of set-rectangular structure patches of copper put diagonally,at the most noteworthy purpose of the FR4 dielectric substrate and a steady ground plane of copper. The proposed shape demonstrates the broadband response of a maintenance exchange speed of two.7 GHz with more than 90 five% absorptivity degree starting from 6.nine GHz to nine.6 GHz.It shows wideband ingestion upto forty five dimensions scene edges underneath underhanded recurrence for each TE and TM polarizations.

scholarly journals Polarization-Controlled and Flexible Single-/Penta-Band Metamaterial Absorber

Materials ◽  
2018 ◽  
Vol 11 (9) ◽  
pp. 1619 ◽  
Author(s):  
Jiayun Wang ◽  
Rongcao Yang ◽  
Jianping Xu ◽  
Jinping Tian ◽  
Runbo Ma ◽  
...  
Keyword(s):  
Incident Angle ◽  
Surface Current ◽  
Dielectric Substrate ◽  
Transverse Magnetic ◽  
Electric Polarization ◽  
Metamaterial Absorber ◽  
Substrate Material ◽  
Absorption Peak ◽  
Absorption Mechanism ◽  
Simulation Results

In this paper, a polarization-controlled and flexible metamaterial absorber made of a set of wires etched on ultrathin teflon dielectric substrate is proposed. The simulation results showed that the proposed absorber achieved single-band absorptivity of 99.8% at 6.64 GHz for the TM (transverse magnetic) polarization wave and penta-band absorptivity of more than 99% at 11.68 GHz, 13.58 GHz, 15.48 GHz, 17.38 GHz, and 19.28 GHz for the TE (transverse electric) polarization waves. Moreover, each absorption peak had very narrow relative bandwidth and the position of penta-band absorption peaks could be adjusted by changing the length of the corresponding wire or selecting suitable substrate material according to actual requirements, because each wire can independently respond to electromagnetic (EM) waves. Furthermore, the surface current distributions corresponding to each absorption peak were studied to demonstrate the absorption mechanism. The absorption properties of the proposed structure with different bending radii and under different incident angles of the EM waves were investigated, showing good flexibility and incident angle-insensitive properties. In addition, the simulation results were confirmed by measuring a fabricated prototype. The proposed absorber may have useful applications in polarizers, sensors, bolometers, polarization detectors, etc.

Structure Information From Electron Diffraction Intensities

1990 ◽  
Vol 48 (2) ◽  
pp. 516-517
Author(s):  
J. Gjønnes ◽  
N. Bøe ◽  
K. Gjønnes
Keyword(s):  
Computational Effort ◽  
Unit Cell ◽  
Small Unit ◽  
Structure Information ◽  
Dispersion Surface ◽  
Integrated Intensity ◽  
The One ◽  
Image Position ◽  
Convergent Beam ◽  
Beam Patterns

Structure information of high precision can be extracted from intentsity details in convergent beam patterns like the one reproduced in Fig 1. From low order reflections for small unit cell crystals,bonding charges, ionicities and atomic parameters can be derived, (Zuo, Spence and O’Keefe, 1988; Zuo, Spence and Høier 1989; Gjønnes, Matsuhata and Taftø, 1989) , but extension to larger unit cell ma seem difficult. The disks must then be reduced in order to avoid overlap calculations will become more complex and intensity features often less distinct Several avenues may be then explored: increased computational effort in order to handle the necessary many-parameter dynamical calculations; use of zone axis intensities at symmetry positions within the CBED disks, as in Figure 2 measurement of integrated intensity across K-line segments. In the last case measurable quantities which are well defined also from a theoretical viewpoint can be related to a two-beam like expression for the intensity profile:With as an effective Fourier potential equated to a gap at the dispersion surface, this intensity can be integrated across the line, with kinematical and dynamical limits proportional to and at low and high thickness respctively (Blackman, 1939).

Toward quantitative defect analysis using HREM

1994 ◽  
Vol 52 ◽  
pp. 714-715
Author(s):  
David J. Smith
Keyword(s):  
Electron Microscope ◽  
Unit Cell ◽  
Defect Analysis ◽  
Significant Progress ◽  
Detailed Characterization ◽  
Small Unit ◽  
Resolution Electron ◽  
High Resolution Electron Microscope ◽  
Large Unit Cell ◽  
Made In

The electron microscope has evolved to the level where it is now straightforward to record highresolution images from thin samples (t∼10 to 20nm) that are directly interpretable in terms of atomic arrangements. Whilst recorded images necessarily represent two-dimensional projections of the structure, many defects such as dislocations and interfaces may be linear or planar in nature and thus might be expected to be amenable to detailed characterization. In this review, we briefly consider the recent significant progress that has been made in quantitative defect analysis using the high-resolution electron microscope and then discuss some drawbacks to the technique as well as potential scope for further improvements. Surveys of defect modelling for some small-unit-cell materials and interfaces have recently been published, and reference should be made to other papers in this symposium for further examples.The technique of structure imaging originated in the early '70s with observations of large-unit-cell block oxides.

Single-peak-regulation and wide-angle dual-band metamaterial absorber based on hollow-cross and solid-cross resonators

2020 ◽  
Vol 91 (3) ◽  
pp. 30901
Author(s):  
Yibo Tang ◽  
Longhui He ◽  
Jianming Xu ◽  
Hailang He ◽  
Yuhan Li ◽  
...  
Keyword(s):  
Transverse Electric ◽  
Surface Current ◽  
Dielectric Substrate ◽  
Transverse Magnetic ◽  
Metamaterial Absorber ◽  
Absorption Peak ◽  
Dual Band ◽  
Single Peak ◽  
Wide Angle ◽  
Surface Current Density

A dual-band microwave metamaterial absorber with single-peak regulation and wide-angle absorption has been proposed and illustrated. The designed metamaterial absorber is consisted of hollow-cross resonators, solid-cross resonators, dielectric substrate and metallic background plane. Strong absorption peak coefficients of 99.92% and 99.55% are achieved at 8.42 and 11.31 GHz, respectively, which is basically consistent with the experimental results. Surface current density and changing material properties are employed to illustrate the absorptive mechanism. More importantly, the proposed dual-band metamaterial absorber has the adjustable property of single absorption peak and could operate well at wide incidence angles for both transverse electric (TE) and transverse magnetic (TM) waves. Research results could provide and enrich instructive guidances for realizing a single-peak-regulation and wide-angle dual-band metamaterial absorber.

scholarly journals Independently Tunable Multipurpose Absorber with Single Layer of Metal-Graphene Metamaterials

Materials ◽  
2021 ◽  
Vol 14 (2) ◽  
pp. 284
Author(s):  
Chen Han ◽  
Renbin Zhong ◽  
Zekun Liang ◽  
Long Yang ◽  
Zheng Fang ◽  
...  
Keyword(s):  
Energy Harvesting ◽  
Fermi Level ◽  
Potential Application ◽  
Single Layer ◽  
Wide Band ◽  
Metamaterial Absorber ◽  
Unit Cell ◽  
Perfect Absorption ◽  
Solar Energy Harvesting ◽  
Band Absorption

This paper reports an independently tunable graphene-based metamaterial absorber (GMA) designed by etching two cascaded resonators with dissimilar sizes in the unit cell. Two perfect absorption peaks were obtained at 6.94 and 10.68 μm with simple single-layer metal-graphene metamaterials; the peaks show absorption values higher than 99%. The mechanism of absorption was analyzed theoretically. The independent tunability of the metamaterial absorber (MA) was realized by varying the Fermi level of graphene under a set of resonators. Furthermore, multi-band and wide-band absorption were observed by the proposed structure upon increasing the number of resonators and resizing them in the unit cell. The obtained results demonstrate the multipurpose performance of this type of absorber and indicate its potential application in diverse applications, such as solar energy harvesting and thermal absorbing.

Development of small unit cell avalanche photodiodes for UV imaging applications

2012 ◽  
Author(s):  
Ashok K. Sood ◽  
Roger E. Welser ◽  
Robert A. Richwine ◽  
Yash R. Puri ◽  
Russell D. Dupuis ◽  
...  
Keyword(s):  
Avalanche Photodiodes ◽  
Unit Cell ◽  
Small Unit ◽  
Uv Imaging ◽  
Small Unit Cell

scholarly journals Hybrid Metamaterials Perfect Absorber and Sensitive Sensor in Optical Communication Band

2021 ◽  
Vol 9 ◽  
Author(s):  
Xuehan Liu ◽  
Keyang Li ◽  
Zhao Meng ◽  
Zhun Zhang ◽  
Zhongchao Wei
Keyword(s):  
Optical Communication ◽  
Electromagnetic Waves ◽  
Incident Angle ◽  
Silicon Layer ◽  
Resonance Wavelength ◽  
Metamaterial Absorber ◽  
Absorption Peak ◽  
Dual Band ◽  
Perfect Absorber ◽  
Perfect Absorption

A subwavelength metamaterial perfect absorber (MPA) in optical communication band was proposed and tested using the finite-difference time-domain method. The absorber is periodic and comprises a top layer of diamond silicon surrounded by L-shaped silicon and a gold layer on the substrate. It can achieve dual-band perfect absorption, and one of the peaks is in the optical communication band. By changing the gap (g) between two adjacent pieces of L-shaped silicon, and the thickness (h) of the silicon layer, the resonance wavelength of absorption peak can be tuned. When the incident electromagnetic wave entered the absorber, the metamaterial absorber could almost completely consume the incident electromagnetic waves, thereby achieving more than 99% perfect absorption. The absorption peak reaches 99.986% at 1310 nm and 99.421% at 1550 nm. Moreover, the MPA exposed to different ambient refraction indexes can be applied as plasma sensors, and can achieve multi-channel absorption with high figure of merit (FOM*) value and refractive index (RI) sensitivity. The FOM* values at 1310 nm and 1550 nm are 6615 and 168, respectively, and both resonance peaks have highly RI sensitivity. The results confirm that the MPA is a dual-band, polarization-independent, wide-angle absorber and insensitive to incident angle. Thence it can be applied in the fields of optical communication, used as a light-wave filter and plasma sensor, and so on.

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