scholarly journals Electromagnetic Metasurfaces and Reconfigurable Metasurfaces: A Review

2021 ◽  
Vol 8 ◽  
Author(s):  
Sidrish Zahra ◽  
Liang Ma ◽  
Wenjiao Wang ◽  
Jian Li ◽  
Dexu Chen ◽  
...  
Keyword(s):  
Electromagnetic Waves ◽  
Polarization State ◽  
Development Trend ◽  
Electromagnetic Properties ◽  
Material Structure ◽  
The Novel ◽  
Practical Applications ◽  
Main Research ◽  
Cell Structures ◽  
Electromagnetic Characteristics

Metamaterial is a kind of material/structure that is artificially designed and has exceptional electromagnetic properties and/or other physical properties, not found in nature. A class of electromagnetic metamaterial with only one or a few layers of periodic or aperiodic arranged cell structures in the direction of electromagnetic waves propagation can be referred to as a metasurface. Metasurface can be considered as a two-dimensional representation of metamaterial and can realize the controlling of the amplitude, phase, and polarization state/direction of the incident electromagnetic wave. According to the novel electromagnetic characteristics of metasurface and its big advantages, a series of new planar devices and systems based on metasurface can be developed. The goal of this review article is firstly to provide introductions for basic metasurface, its significance properties, and application principles. Meanwhile, the main research progresses of regular metasurfaces and the newly developed reconfigurable metasurfaces are analyzed, focusing on the types of amplitude modulation, phase modulation, polarization modulation, and multidimensional modulation. Finally, the research significances of metasurface development trend and important engineering practical applications are analyzed in the end.

scholarly journals Design and experimental analysis of dual-band polarization converting metasurface for microwave applications

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Bilawal Khan ◽  
Babar Kamal ◽  
Sadiq Ullah ◽  
Imran Khan ◽  
Jawad Ali Shah ◽  
...  
Keyword(s):  
Electromagnetic Waves ◽  
Polarization State ◽  
Plane Waves ◽  
Microwave Frequency ◽  
Dual Band ◽  
Orthogonal Polarization ◽  
Frequency Bands ◽  
Practical Applications ◽  
Sensor Applications ◽  
Polarized Waves

Abstract The manipulation of polarization state of electromagnetic waves is of great importance in many practical applications. In this paper, the reflection characteristics of a thin and dual-band metasurface are examined in the microwave frequency regime. The metasurface consists of a 22 × 22 element array of periodic unit cells. The geometry of the unit cell consists of three layers, including a 45° inclined dipole shape metal patch on top, which is backed by a 1.6 mm thick FR-4 substrate in the middle, and a fully reflective metallic mirror at the bottom. The proposed surface is exposed to horizontally (x) or vertically (y) polarized plane waves and the co and cross polarization reflection coefficients of the reflected waves are investigated experimentally in the 6–26 GHz frequency range. The metasurface is designed to convert incident waves of known polarization state (horizontal or vertical) to orthogonal polarization state (vertical and horizontal) in two distinct frequency bands, i.e. 7.1–8 GHz and 13.3–25.8 GHz. In these two frequency bands the simulated and experimental results are in good agreement. The polarization conversion ratio (PCR) of the surface is greater than 95% in the targeted frequency bands. A detailed parametric analysis of the metasurface is also discussed in this work and it has been estimated that the surface has the additional ability to convert linearly polarized waves to circularly polarized waves at several distinct frequencies. The proposed metasurface can be utilized in sensor applications, stealth technology, electromagnetic measurements, and antennas design.

MEASURING OF SPECTRAL FRACTAL DIMENSION

2007 ◽  
Vol 03 (03) ◽  
pp. 409-418 ◽  
Author(s):  
JÓZSEF BERKE
Keyword(s):  
Information Technology ◽  
Fractal Dimension ◽  
Material Structure ◽  
The Novel ◽  
Mathematical Concepts ◽  
Mathematical Basis ◽  
Great Expectations ◽  
Practical Applications ◽  
Computer Classification ◽  
Definition Of

There were great expectations in the 1980s in connection with the practical applications of mathematical processes which were built mainly upon the fractal dimension, mathematical basis. Results were achieved in the first times in several fields: examination of material structure, simulation of chaotic phenomena (earthquake, tornado), modeling real processing with the help of the information technology and its equipments, the definition of the length of rivers or riverbanks. Significant results were also achieved later in practical applications in the fields of information technology, certain image processing areas, data compression, and computer classification. In this paper, the well known algorithms calculating fractal dimension in a much simplified manner will be presented. The novel mathematical concepts, named by the author as 'Spectral Fractal Dimension' are also described in this paper.

Recent Patents on the Angular Contact Ball Bearing of High-Speed Motorized Spindle

2020 ◽  
Vol 13 ◽  
Author(s):  
Yudong Bao ◽  
Linkai Wu ◽  
Yanling Zhao ◽  
Chengyi Pan
Keyword(s):  
High Speed ◽  
Ball Bearing ◽  
Rapid Development ◽  
Ceramic Materials ◽  
Development Trend ◽  
Numerical Control ◽  
Angular Contact Ball Bearing ◽  
Practical Applications ◽  
High Speed Cutting ◽  
Advantages And Disadvantages

Background:: Angular contact ball bearings are the most popular bearing type used in the high speed spindle for machining centers, The performance of the bearing directly affects the machining efficiency of the machine tool, Obtaining a higher value is the direction of its research and development. Objective:: By analyzing the research achievements and patents of electric spindle angular contact bearings, summarizing the development trend provides a reference for the development of electric spindle bearings. Methods:: Through the analysis of the relevant technology of the electric spindle angular contact ball bearing, the advantages and disadvantages of the angular contact ball bearing are introduced, and the research results are combined with the patent analysis. Results:: With the rapid development of high-speed cutting and numerical control technology and the needs of practical applications, the spindle requires higher and higher speeds for bearings. In order to meet the requirements of use, it is necessary to improve the bearing performance by optimizing the structure size and improving the lubrication conditions. Meanwhile, reasonable processing and assembly methods will also have a beneficial effect on bearing performance. Conclusion:: With the continuous deepening of bearing technology research and the use of new structures and ceramic materials has made the bearing's limit speed repeatedly reach new highs. The future development trend of high-speed bearings for electric spindles is environmental protection, intelligence, high speed, high precision and long life.

scholarly journals Preparation and electromagnetic properties characterization of reduced graphene oxide/strontium hexaferrite nanocomposites

2020 ◽  
Vol 9 (1) ◽  
pp. 105-114 ◽  
Author(s):  
Shumin Du ◽  
Huaiyin Chen ◽  
Ruoyu Hong
Keyword(s):  
Electromagnetic Wave ◽  
Environmental Pollution ◽  
Electromagnetic Interference ◽  
Electromagnetic Waves ◽  
Rapid Development ◽  
Living Environment ◽  
World Health ◽  
Electromagnetic Properties ◽  
Strontium Hexaferrite ◽  
Wave Radiation

AbstractWith the rapid development of electronics and information technology, electronics and electrical equipment have been widely used in our daily lives. The living environment is full of electromagnetic waves of various frequencies and energy. Electromagnetic wave radiation has evolved into a new type of environmental pollution that has been listed by the WHO (World Health Organization) as the fourth largest source of environmental pollution after water, atmosphere, and noise. Studies have shown that when electromagnetic wave radiation is too much, it can cause neurological disorders. And electromagnetic interference will cause the abnormal operation of medical equipment, precision instruments and other equipment, and therefore cause incalculable consequences. Therefore, electromagnetic protection has become a hot issue of concern to the social and scientific circles.

scholarly journals Microparticles, Microspheres, and Microcapsules for Advanced Drug Delivery

2019 ◽  
Vol 87 (3) ◽  
pp. 20 ◽  
Author(s):  
Miléna Lengyel ◽  
Nikolett Kállai-Szabó ◽  
Vince Antal ◽  
András József Laki ◽  
István Antal
Keyword(s):  
Drug Delivery ◽  
Drug Delivery Systems ◽  
Freeze Drying ◽  
Delivery Systems ◽  
The Novel ◽  
Practical Applications ◽  
Inhaled Insulin ◽  
Formulation Factors ◽  
Novel Drug ◽  
Significant Production

Microparticles, microspheres, and microcapsules are widely used constituents of multiparticulate drug delivery systems, offering both therapeutic and technological advantages. Microparticles are generally in the 1–1000 µm size range, serve as multiunit drug delivery systems with well-defined physiological and pharmacokinetic benefits in order to improve the effectiveness, tolerability, and patient compliance. This paper reviews their evolution, significance, and formulation factors (excipients and procedures), as well as their most important practical applications (inhaled insulin, liposomal preparations). The article presents the most important structures of microparticles (microspheres, microcapsules, coated pellets, etc.), interpreted with microscopic images too. The most significant production processes (spray drying, extrusion, coacervation, freeze-drying, microfluidics), the drug release mechanisms, and the commonly used excipients, the characterization, and the novel drug delivery systems (microbubbles, microsponges), as well as the preparations used in therapy are discussed in detail.

Core–Shell Chain-Like Cu@Ni Composite with Dual Absorption Peaks to Improve Microwave Absorption Properties

NANO ◽  
2018 ◽  
Vol 13 (05) ◽  
pp. 1850052
Author(s):  
Yuanyuan Zhou ◽  
Jianying Deng ◽  
Shimei Li ◽  
Zefeng Li
Keyword(s):  
Hydrothermal Reaction ◽  
Low Cost ◽  
Electromagnetic Properties ◽  
Formation Mechanisms ◽  
Core Shell ◽  
The Novel ◽  
Redox Potentials ◽  
X Ray Diffraction ◽  
Ni Alloy ◽  
Absorbing Material

Core–shell Cu@Ni chains were successfully synthesized through a mild hydrothermal reaction. The morphology, structure and microwave electromagnetic properties of the composite were then characterized by X-ray diffraction, energy-dispersive spectroscopy, scanning electron microscopy and vector network analysis. The formation mechanisms of the core–shell structure and one-dimensional chains were ascribed to the varying redox potentials of Cu and Ni ions and the magnetic dipole–dipole attraction. Furthermore, a minimal reflection loss (RL) of [Formula: see text]20.7[Formula: see text]dB was observed at 9.6[Formula: see text]GHz with a thickness of 2.0[Formula: see text]mm and the effective absorption ([Formula: see text]10[Formula: see text]dB, 90% microwave attenuation) bandwidth can be adjusted between 5.2[Formula: see text]GHz and 16.6[Formula: see text]GHz for the thin absorber thickness of 2.0–4.0[Formula: see text]mm. The novel core–shell chain-like Cu@Ni alloy can be used as a promising absorbing material because it shows numerous features such as thin thickness, strong absorption, low cost and lightweight.

MXene nanohybrids: Excellent electromagnetic properties for absorbing electromagnetic waves

2021 ◽  
Author(s):  
Peng He ◽  
Meng-Jiao Zheng ◽  
Qi Liu ◽  
Zi-Yi Liu ◽  
Ru-Zhong Zuo ◽  
...  
Keyword(s):  
Electromagnetic Waves ◽  
Electromagnetic Properties

NONRECIPROCAL ELECTROMAGNETIC DEVICES IN GYROMAGNETIC PHOTONIC CRYSTALS

2013 ◽  
Vol 28 (02) ◽  
pp. 1441010 ◽  
Author(s):  
ZHI-YUAN LI ◽  
RONG-JUAN LIU ◽  
LIN GAN ◽  
JIN-XIN FU ◽  
JIN LIAN
Keyword(s):  
Magnetic Field ◽  
Band Gap ◽  
Electromagnetic Waves ◽  
Experimental Studies ◽  
Magnetic Surface ◽  
Electromagnetic Properties ◽  
Edge States ◽  
Bragg Scattering ◽  
Electromagnetic Devices ◽  
Gap Opening

Gyromagnetic photonic crystal (GPC) offers a promising way to realize robust transport of electromagnetic waves against backscattering from various disorders, perturbations and obstacles due to existence of unique topological electromagnetic states. The dc magnetic field exerting upon the GPC brings about the time-reversal symmetry breaking, splits the band degeneracy and opens band gaps where the topological chiral edge states (CESs) arise. The band gap can originate either from long-range Bragg-scattering effect or from short-range localized magnetic surface plasmon resonance (MSP). These topological edge states can be explored to construct backscattering-immune one-way waveguide and other nonreciprocal electromagnetic devices. In this paper we review our recent theoretical and experimental studies of the unique electromagnetic properties of nonreciprocal devices built in GPCs. We will discuss various basic issues like experimental instrumental setup, sample preparations, numerical simulation methods, tunable properties against magnetic field, band degeneracy breaking and band gap opening and creation of topological CESs. We will investigate the unidirectional transport properties of one-way waveguide under the influence of waveguide geometries, interface morphologies, intruding obstacles, impedance mismatch, lattice disorders, and material dissipation loss. We will discuss the unique coupling properties between one-wave waveguide and resonant cavities and their application as novel one-way bandstop filter and one-way channel-drop filter. We will also compare the CESs created in the Bragg-scattering band gap and the MSP band gap under the influence of lattice disorders. These results can be helpful for designing and exploring novel nonreciprocal electromagnetic devices for optical integration and information processing.

scholarly journals A Small-Divergence-Angle Orbital Angular Momentum Metasurface Antenna

Research ◽  
2019 ◽  
Vol 2019 ◽  
pp. 1-8 ◽  
Author(s):  
Jianchun Xu ◽  
Ke Bi ◽  
Ru Zhang ◽  
Yanan Hao ◽  
Chuwen Lan ◽  
...  
Keyword(s):  
Angular Momentum ◽  
Orbital Angular Momentum ◽  
Electromagnetic Waves ◽  
Divergence Angle ◽  
Compact Structure ◽  
Phase Gradient ◽  
Practical Applications ◽  
Circular Arrangement ◽  
Low Efficiency ◽  
Theoretical Analyses

Electromagnetic waves carrying an orbital angular momentum (OAM) are of great interest. However, most OAM antennas present disadvantages such as a complicated structure, low efficiency, and large divergence angle, which prevents their practical applications. So far, there are few papers and research focuses on the problem of the divergence angle. Herein, a metasurface antenna is proposed to obtain the OAM beams with a small divergence angle. The circular arrangement and phase gradient were used to simplify the structure of the metasurface and obtain the small divergence angle, respectively. The proposed metasurface antenna presents a high transmission coefficient and effectively decreases the divergence angle of the OAM beam. All the theoretical analyses and derivation calculations were validated by both simulations and experiments. This compact structure paves the way to generate OAM beams with a small divergence angle.

Microwave filters on cavity resonators

2021 ◽  
Author(s):  
V.V. Komarov ◽  
S.K. Bushanskiy ◽  
A.O. Churkin
Keyword(s):  
High Power ◽  
Electromagnetic Waves ◽  
Complex Shape ◽  
Microwave Filters ◽  
Electronic Systems ◽  
Microwave Range ◽  
Cavity Resonators ◽  
Electromagnetic Characteristics ◽  
Technical Solutions

Waveguide and cavity microwave filters continue to be the most important components of high-power radio electronic systems. Cavity microwave filters are of great interest as a separate group of devices of this type. The fields of application of such filters are constantly expanding, and the variety of their design is quite large. In addition, the requirements for their electromagnetic characteristics and reliability are currently increasing. In this regard, it becomes necessary to analyze the already created designs of these devices and study the main trends of their improvement. The objective of the present study is to review the known technical solutions of bandpass filters, made on cavity resonators of the microwave range. An overview of the designs of devices for filtering electromagnetic waves on cavity resonators with coaxial and waveguide coupling elements of various frequency ranges is carried out. It is proposed to use the configuration of basic resonators as the main criterion for the classification of these devices. In accordance with this criterion, five groups of filters are considered: on rectangular, cylindrical, spherical, coaxial resonators, as well as on resonators of complex shape. The review makes it possible to analyze the features of the implementation of different technical solutions for bandpass microwave filters of medium and high power levels and to identify the main trends in the development of this area of research.

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