scholarly journals Circular ring shaped ultra-wideband metamaterial absorber with polarization insensitivity for energy harvesting

2022 ◽  
Vol 12 (2) ◽  
pp. 1243
Author(s):  
John Bosco John Paul ◽  
Aruldas Shobha Rekh
Keyword(s):  
Low Cost ◽  
Metamaterial Absorber ◽  
Circular Ring ◽  
Unit Cell ◽  
Ultra Wideband ◽  
High Frequency Structure Simulator ◽  
Array Structures ◽  
Strip Lines ◽  
Unit Cell Dimensions ◽  
Absorption Characteristics

<span>A circular ring-shaped metamaterial (CRM) absorber was designed to harvest radio frequency (RF) energy in the ultra-wideband (UWB) frequency band applications. The proposed metamaterial unit cell features a circular shaped structure, with rectangular strip lines connected in the form of a cross leaving a square shaped slot at center. The unit cell dimensions are 15×15×1.6 mm. The absorber was etched on a low cost FR4 substrate having a dielectric constant of 4.4. Ansys high frequency structure simulator (HFSS) software was used for simulation and the analysis were carried out for unit cell, 2×2, 3×3, and 4×4 array structures. The absorber parameters plotted are absorption characteristics and reflection characteristics. Also, the metamaterial parameters (μeff) and (εeff) are also retrieved from the absorber parameters and analyzed. From the analysis, the values (μeff) and (εeff) were found to be negative, leaving refractive index also negative (n&lt;0), which proved the metamaterial property. The proposed CRM absorber showed good absorption characteristics of more than 80% and also metamaterial property in the entire UWB band (4-13 GHz). Hence the absorber proves to be a good candidate in powering low power sensors/microcontrollers for internet of things (IoT) applications.</span>

scholarly journals Polarization-Independent Ultra-Wideband Metamaterial Absorber for Solar Harvesting at Infrared Regime

Materials ◽  
2020 ◽  
Vol 13 (11) ◽  
pp. 2560 ◽  
Author(s):  
Asraful Alam ◽  
Sikder Sunbeam Islam ◽  
Md. Hobaibul Islam ◽  
Ali F. Almutairi ◽  
Mohammad Tariqul Islam
Keyword(s):  
Solar Spectrum ◽  
Equivalent Circuit Model ◽  
Metamaterial Absorber ◽  
Simulation Software ◽  
Unit Cell ◽  
Ultra Wideband ◽  
Scattering Parameters ◽  
Frequency Range ◽  
Relative Bandwidth ◽  
Polarization Insensitive

This paper presents an ultra-wideband metamaterial absorber for solar harvesting in the infrared regime (220–360 THz) of the solar spectrum. The proposed absorber consists of square-shaped copper patches of different sizes imposed on a GaAs (Gallium arsenide) substrate. The design and simulation of the unit cell are performed with finite integration technique (FIT)-based simulation software. Scattering parameters are retrieved during the simulation process. The constructed design offers absorbance above 90% within a 37.89% relative bandwidth and 99.99% absorption over a vast portion of the investigated frequency range. An equivalent circuit model is presented to endorse the validity of the proposed structure. The calculated result strongly agrees with the simulated result. Symmetrical construction of the proposed unit cell reports an angular insensitivity up to a 35° oblique incidence. Post-processed simulation data confirm that the design is polarization-insensitive.

Experimental verification of super-compact ultra-wideband (UWB) polarization and incident angle-independent metamaterial absorber

2020 ◽  
pp. 1-11
Author(s):  
Manpreet Kaur ◽  
Hari Shankar Singh
Keyword(s):  
Incident Angle ◽  
Low Cost ◽  
Surface Current ◽  
Cost Effective ◽  
Normal Incidence ◽  
Metamaterial Absorber ◽  
Capacitive Coupling ◽  
Ultra Wideband ◽  
Absorption Mechanism ◽  
The Stability

Abstract In this paper, a super-compact ultra-wideband (UWB) metamaterial absorber (MMA) is presented. The absorber design consists of an inverted L-shaped structure and a diagonal rectangular-shaped structure. The capacitive coupling between these two structures not only provides UWB nature but also provides a super-compact absorber design. The dimension of the unit cell arrangement is 5 × 5 mm2 and printed on a low-cost FR-4 substrate of thickness 1.54 mm (0.061λlowest). The design absorber provides more than 97% absorptivity from 12 to 21 GHz for normal incidence electromagnetic (EM) wave. However, the proposed MMA has a full width at half maximum absorption bandwidth of 11.71 GHz from 10.34 to 22.05 GHz. Moreover, the surface current distributions have been analyzed to understand the absorption mechanism of the MMA. The stability of the proposed design is validated with different incident angles (for TE and TM modes) and different polarization angles. Finally, the absorber design is fabricated and verified experimentally. Furthermore, the UWB frequency range, high absorption, ease in design and fabrication, and cost-effective make it suitable for different quality applications in stealth technology, thermal imaging, radar detection, antenna systems, and other EM devices.

scholarly journals An Ultrathin Graphite Based Absorber for Wearable Applications

2021 ◽  
Author(s):  
Avinash ◽  
Nisha Gupta
Keyword(s):  
Low Cost ◽  
Ground Plane ◽  
Frequency Selective Surface ◽  
Dielectric Substrate ◽  
Experimental Models ◽  
Unit Cell ◽  
Prototype Model ◽  
Angle Of Incidence ◽  
Wearable Electronics ◽  
High Frequency Structure Simulator

Abstract In this paper, a low-cost, flexible, ultrathin absorber comprising a simple square patch-shaped frequency selective surface (FSS) is proposed for wearable applications. The FSS based absorbing structure contains periodic graphite patch pattern placed on a thin paper substrate, and backed with a copper foil-based ground plane. The dimension and periodicity of the unit cell are 0.31λo and 0.36λo respectively, while the thickness of the absorber is approximately λo/85, where λo is the wavelength of free space at 10 GHz. The characteristics of the FSS absorber is optimized in terms of unit cell periodicity, and dielectric substrate height using a full-wave high frequency structure simulator software (HFSS). The effects of the parameters are also examined using equivalent circuit approach. The proposed absorber shows insensitivity towards the angle of incidence as well as angle of polarization. Finally, a prototype model is fabricated, measured, and validated with simulation results. A good agreement is depicted between simulated and experimental models. The proposed absorber finds application in the field of wearable electronics, medical, and automotive applications for effective mitigation of the EMI.

scholarly journals Enhancing the resonance characteristics of circular patch antenna for SHF applications

2021 ◽  
Author(s):  
Mousaab M. Nahas ◽  
Keyword(s):  
Patch Antenna ◽  
High Frequency ◽  
Microstrip Antenna ◽  
Low Cost ◽  
Ground Plane ◽  
Dielectric Substrate ◽  
Ultra Wideband ◽  
Uwb Antenna ◽  
High Frequency Structure Simulator ◽  
Circular Patch Antenna

Microstrip patch antenna is attractive for various applications due to its easy fabrication, low cost and small size. It simply comprises of a radiating patch and ground plane that are separated by a dielectric substrate. However, the resonance bandwidth of the microstrip antenna is still an issue that needs to be considered in research. This paper aims to enhance the bandwidth of a microstrip antenna or introduce more resonant frequencies within the Super High Frequency (SHF) band. The paper demonstrates empirical results for circular-shaped patch antenna using the High Frequency Structure Simulator (HFSS). It begins by investigating different patch sizes and substrate materials, so that an optimal preliminary design is introduced. Then, different slot shapes are inserted into the patch for significant enhancement of the resonance characteristics. As a result, new ultra-wideband (UWB) antenna designs are presented with bandwidth results reaching 15.5 GHz within the C, X, Ku and K bands. Also, new multiband antenna designs are presented with improved reflection valleys in the Ku, K and Ka bands.

The External Shape of Human γ GI Immunoglobulin from Crystal Sections

1971 ◽  
Vol 29 ◽  
pp. 428-429
Author(s):  
L. W. Labaw
Keyword(s):  
Molecular Weight ◽  
Sodium Phosphate ◽  
Osmium Tetroxide ◽  
Unit Cell ◽  
Monoclinic Space Group ◽  
X Ray ◽  
Large Molecular Weight ◽  
Cell Dimensions ◽  
Unit Cell Dimensions ◽  
Crystallographic Axes

Crystals of a human γGl immunoglobulin have the external morphology of diamond shaped prisms. X-ray studies have shown them to be monoclinic, space group C2, with 2 molecules per unit cell. The unit cell dimensions are a = 194.1, b = 91.7, c = 51.6Å, 8 = 102°. The relatively large molecular weight of 151,000 and these unit cell dimensions made this a promising crystal to study in the EM.Crystals similar to those used in the x-ray studies were fixed at 5°C for three weeks in a solution of mother liquor containing 5 x 10-5M sodium phosphate, pH 7.0, and 0.03% glutaraldehyde. They were postfixed with 1% osmium tetroxide for 15 min. and embedded in Maraglas the usual way. Sections were cut perpendicular to the three crystallographic axes. Such a section cut with its plane perpendicular to the z direction is shown in Fig. 1.This projection of the crystal in the z direction shows periodicities in at least four different directions but these are only seen clearly by sighting obliquely along the micrograph.

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.

scholarly journals Sunflower-Like Nanostructure with Built-In Hotspots for Alpha-Fetoprotein Detection

Molecules ◽  
2021 ◽  
Vol 26 (4) ◽  
pp. 1197
Author(s):  
Xiaoyu Zhao ◽  
Aonan Zhu ◽  
Yaxin Wang ◽  
Yongjun Zhang ◽  
Xiaolong Zhang
Keyword(s):  
Rapid Detection ◽  
Clinical Medicine ◽  
Electromagnetic Coupling ◽  
Low Cost ◽  
Surface Enhanced Raman Spectroscopy ◽  
Alpha Fetoprotein ◽  
Low Concentrations ◽  
Surface Enhanced Raman ◽  
Active Substrate ◽  
Array Structures

In the present study, a sunflower-like nanostructure array composed of a series of synaptic nanoparticles and nanospheres was manufactured through an efficient and low-cost colloidal lithography technique. The primary electromagnetic field contribution generated by the synaptic nanoparticles of the surface array structures was also determined by a finite-difference time-domain software to simulate the hotspots. This structure exhibited high repeatability and excellent sensitivity; hence, it was used as a surface-enhanced Raman spectroscopy (SERS) active substrate to achieve a rapid detection of ultra-low concentrations of Alpha-fetoprotein (AFP). This study demonstrates the design of a plasmonic structure with strong electromagnetic coupling, which can be used for the rapid detection of AFP concentration in clinical medicine.

scholarly journals Realization of frequency hopping characteristics of an epsilon negative metamaterial with high effective medium ratio for multiband microwave applications

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Mohammad Tariqul Islam ◽  
Md. Moniruzzaman ◽  
Touhidul Alam ◽  
Md Samsuzzaman ◽  
Qutaiba A. Razouqi ◽  
...  
Keyword(s):  
Refractive Index ◽  
Low Cost ◽  
Frequency Hopping ◽  
Small Dimension ◽  
Effective Medium ◽  
Unit Cell ◽  
Negative Permittivity ◽  
Design System ◽  
Microwave Applications ◽  
Meander Line

AbstractIn this paper, a meander-lines-based epsilon negative (ENG) metamaterial (MTM) with a high effective medium ratio (EMR) and near-zero refractive index (NZI) is designed and investigated for multiband microwave applications. The metamaterial unit cell is a modification of the conventional square split-ring resonator in which the meander line concept is utilized. The meander line helps to increase the electrical length of the rings and provides strong multiple resonances within a small dimension. The unit cell of proposed MTM is initiated on a low-cost FR4 substrate of 1.5 mm thick and electrical dimension of 0.06λ × 0.06λ, where wavelength, λ is calculated at the lowest resonance frequency (2.48 GHz). The MTM provides four major resonances of transmission coefficient (S21) at 2.48, 4.28, 9.36, and 13.7 GHz covering S, C, X, and Ku bands. It shows negative permittivity, near-zero permeability, and near-zero refractive index in the vicinity of these resonances. The equivalent circuit is designed and modeled in Advanced Design System (ADS) software. The simulated S21 of the MTM unit cell is compared with the measured one and both show close similarity. The array performance of the MTM is also evaluated by using 2 × 2, 4 × 4, and 8 × 8 arrays that show close resemblance with the unit cell. The MTM offers a high effective medium ratio (EMR) of 15.1, indicating the design's compactness. The frequency hopping characteristics of the proposed MTM is investigated by open and short-circuited the three outer rings split gaps by using three switches. Eight different combinations of the switching states provide eight different sets of multiband resonances within 2–18 GHz; those give the flexibility of using the proposed MTM operating in various frequency bands. For its small dimension, NZI, high EMR, and frequency hopping characteristics through switching, this metamaterial can be utilized for multiband microwave applications, especially to enhance the gain of multiband antennas.

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