scholarly journals DISTORTIONLESS SIGNALS TRANSFER THROUGH A WIRE MEDIA METASTRUCTURE

2018 ◽  
Vol 8 (1) ◽  
pp. 44-47 ◽  
Author(s):  
Dmytro Vovchuk ◽  
Serhii Haliuk ◽  
Leonid Politanskyy
Keyword(s):  
Electromagnetic Waves ◽  
Spectral Characteristics ◽  
Wide Frequency Range ◽  
Power Transfer ◽  
Fabry Perot ◽  
Signal Distortions ◽  
Metallic Wires ◽  
The Wire ◽  
Wire Media ◽  
First Time

In the paper the development of the components of communication means is considered based on the wire metastructures. This approach is novel and quite promising due to the metamaterials provides new opportunities for the radio engineering devices such as antennas, absorbers etc. First of all it makes possible decreasing of the dimensions of devices while the characteristics stay the same or better. Here the artificially created metastructure that consists of parallel metallic wires and characterizes by a negative electric permittivity was investigated. The possibility of broadband power transfer of electromagnetic waves was demonstrated. Also, at first time, the investigation of possible signal distortions due to wave propagation through the wire medium (WM) slab was performed via analyzing of spectral characteristics. The obtained results allow applying of WM to power transfer in wide frequency range (not only at frequencies of Fabry-Perot resonant) and enhancement of weak source propagation as well as to antennas constructions due to the absence of signal distortions. One of the promising applications of such structures is the possibility of realizing of flexible screens with nanometer thickness and high resolution.

scholarly journals OVERVIEW OF APPLICATIONS OF WIRE MEDIUM IN RADIO ENGINEERING MEANS

2018 ◽  
Vol 8 (4) ◽  
pp. 32-35
Author(s):  
Mykola Khobzei ◽  
Dmytro Vovchuk ◽  
Magdalena Michalska
Keyword(s):  
Microwave Frequency ◽  
Wide Frequency Range ◽  
Electromagnetic Properties ◽  
Photovoltaic Devices ◽  
Frequency Range ◽  
Radio Engineering ◽  
Different Shapes ◽  
The Wire ◽  
Wire Media ◽  
Power Radiation

This paper presents an overview of the main possible applications of wire medium in different field of radio engineering. Wire media possesses the unique electromagnetic properties. There is a number for approaches for manufacturing the wire media of different shapes from microwave frequency up to optical one. The wire media that consists of parallel metallic rods finds application for narrow and broadband power radiation in photovoltaic devices, imaging, endoscopy and many others. The wire metastructures such as hyperlens and brush are applicable to the antennas of wide frequency range.

scholarly journals Wireless power transfer system rigid to tissue characteristics using metamaterial inspired geometry for biomedical implant applications

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Ramesh K. Pokharel ◽  
Adel Barakat ◽  
Shimaa Alshhawy ◽  
Kuniaki Yoshitomi ◽  
Costas Sarris
Keyword(s):  
Electromagnetic Waves ◽  
Wireless Power Transfer ◽  
Split Ring Resonator ◽  
Input Power ◽  
Power Transfer ◽  
Wireless Power ◽  
Biomedical Implant ◽  
Safety Regulations ◽  
Wireless Power Transfer System ◽  
Tissue Characteristics

AbstractConventional resonant inductive coupling wireless power transfer (WPT) systems encounter performance degradation while energizing biomedical implants. This degradation results from the dielectric and conductive characteristics of the tissue, which cause increased radiation and conduction losses, respectively. Moreover, the proximity of a resonator to the high permittivity tissue causes a change in its operating frequency if misalignment occurs. In this report, we propose a metamaterial inspired geometry with near-zero permeability property to overcome these mentioned problems. This metamaterial inspired geometry is stacked split ring resonator metamaterial fed by a driving inductive loop and acts as a WPT transmitter for an in-tissue implanted WPT receiver. The presented demonstrations have confirmed that the proposed metamaterial inspired WPT system outperforms the conventional one. Also, the resonance frequency of the proposed metamaterial inspired TX is negligibly affected by the tissue characteristics, which is of great interest from the design and operation prospects. Furthermore, the proposed WPT system can be used with more than twice the input power of the conventional one while complying with the safety regulations of electromagnetic waves exposure.

scholarly journals Coherently Driven and Superdirective Antennas

Electronics ◽  
2019 ◽  
Vol 8 (8) ◽  
pp. 845 ◽  
Author(s):  
Alex Krasnok
Keyword(s):  
Dielectric Resonator ◽  
Electromagnetic Waves ◽  
Wireless Power Transfer ◽  
Higher Order ◽  
Power Transfer ◽  
Wireless Power ◽  
Entire Spectrum ◽  
Guided Mode ◽  
Dielectric Antennas ◽  
Antenna Systems

Antennas are crucial elements for wireless technologies, communications and power transfer across the entire spectrum of electromagnetic waves, including radio, microwaves, THz and optics. In this paper, we review our recent achievements in two promising areas: coherently enhanced wireless power transfer (WPT) and superdirective dielectric antennas. We show that the concept of coherently enhanced WPT allows improvement of the antenna receiving efficiency by coherent excitation of the outcoupling waveguide with a backward propagating guided mode with a specific amplitude and phase. Antennas with the superdirectivity effect can increase the WPT system’s performance in another way, through tailoring of radiation diagram via engineering antenna multipoles excitation and interference of their radiation. We demonstrate a way to achieve the superdirectivity effect via higher-order multipoles excitation in a subwavelength high-index spherical dielectric resonator supporting electric and magnetic Mie multipoles. Thus, both types of antenna discussed here possess a coherent nature and can be used in modern intelligent antenna systems.

scholarly journals New Poly(Propylene Imine) Dendrimer Modified with Acridine and Its Cu(II) Complex: Synthesis, Characterization and Antimicrobial Activity

Materials ◽  
2019 ◽  
Vol 12 (18) ◽  
pp. 3020 ◽  
Author(s):  
Paula Bosch ◽  
Desislava Staneva ◽  
Evgenia Vasileva-Tonkova ◽  
Petar Grozdanov ◽  
Ivanka Nikolova ◽  
...  
Keyword(s):  
Antimicrobial Activity ◽  
Copper Ions ◽  
Spectral Characteristics ◽  
Dilution Method ◽  
Pathogenic Microorganisms ◽  
Paramagnetic Resonance ◽  
Poly Propylene ◽  
New Compounds ◽  
First Time

A second-generation poly(propylene imine) dendrimer modified with acridine and its Cu(II) complex have been synthesized for the first time. It has been found that two copper ions form complexes with the nitrogen atoms of the dendrimeric core by coordinate bonds. The new compounds have been characterized by nuclear magnetic resonance (NMR), electron paramagnetic resonance (EPR), fourier-transform infrared spectroscopy (FTIR) and fluorescence spectroscopy. The spectral characteristics of the modified dendrimer have been measured in different organic solvents, and a negative fluorescence solvatochromism has been observed. The antimicrobial activity of the dendrimers has been tested against model pathogenic microorganisms in agar and by broth dilution method. The cotton fabric treated with both dendrimers has been evaluated towards pathogenic microorganisms. The obtained modified cotton fabrics have been shown to hamper bacterial growth and to prevent biofilm formation. Dendrimer cytotoxicity has been investigated in vitro in the model HEp-2 cell line.

scholarly journals Model of the propagation of very low-frequency beams in the Earth–ionosphere waveguide: principles of the tensor impedance method in multi-layered gyrotropic waveguides

2020 ◽  
Vol 38 (1) ◽  
pp. 207-230
Author(s):  
Yuriy Rapoport ◽  
Vladimir Grimalsky ◽  
Viktor Fedun ◽  
Oleksiy Agapitov ◽  
John Bonnell ◽  
...  
Keyword(s):  
Optical Waveguides ◽  
Electromagnetic Waves ◽  
Low Frequency ◽  
Signal Propagation ◽  
Wide Frequency Range ◽  
Impedance Method ◽  
Very Low Frequency ◽  
The Earth ◽  
Tensor Impedance ◽  
Electromagnetic Beams

Abstract. The modeling of very low-frequency (VLF) electromagnetic (EM) beam propagation in the Earth–ionosphere waveguide (WGEI) is considered. A new tensor impedance method for modeling the propagation of electromagnetic beams in a multi-layered and inhomogeneous waveguide is presented. The waveguide is assumed to possess the gyrotropy and inhomogeneity with a thick cover layer placed above the waveguide. The influence of geomagnetic field inclination and carrier beam frequency on the characteristics of the polarization transformation in the Earth–ionosphere waveguide is determined. The new method for modeling the propagation of electromagnetic beams allows us to study the (i) propagation of the very low-frequency modes in the Earth–ionosphere waveguide and, in perspective, their excitation by the typical Earth–ionosphere waveguide sources, such as radio wave transmitters and lightning discharges, and (ii) leakage of Earth–ionosphere waveguide waves into the upper ionosphere and magnetosphere. The proposed approach can be applied to the variety of problems related to the analysis of the propagation of electromagnetic waves in layered gyrotropic and anisotropic active media in a wide frequency range, e.g., from the Earth–ionosphere waveguide to the optical waveband, for artificial signal propagation such as metamaterial microwave or optical waveguides.

Effects of Machining Fluid on Electric Discharge Machining of SiC Ingot

2014 ◽  
Vol 778-780 ◽  
pp. 767-770 ◽  
Author(s):  
Norimasa Yamamoto ◽  
Satarou Yamaguchi ◽  
Tomohisa Kato
Keyword(s):  
Surface Roughness ◽  
Silicon Carbide ◽  
Ion Exchange ◽  
Electric Discharge ◽  
Electrical Discharge ◽  
Electrical Discharge Machining ◽  
Electric Discharge Machining ◽  
The Wire ◽  
Characteristic Features ◽  
First Time

Recently, ingots of silicon carbide have been adapted to be sliced by the wire-cut electrical discharge machining. Fast slicing, and the reduction in the loss are important for slicing of the wafer. In this paper, characteristic features of the electric discharge machining in the ion-exchange water and the fluorine-based fluid were compared for these improvement. The discharge was caused by a pulse voltage applied to a ingot of silicon carbide and the wire in machining fluid, and the slicing was proceeded. As a result, improvement of surface roughness and kerf loss was confirmed, for the first time. In addition, the improving methods for fast slicing were considered.

scholarly journals Heating of Ti3C2Tx MXene/polymer composites in response to Radio Frequency fields

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Touseef Habib ◽  
Nutan Patil ◽  
Xiaofei Zhao ◽  
Evan Prehn ◽  
Muhammad Anas ◽  
...  
Keyword(s):  
Radio Frequency ◽  
Thermal Imaging ◽  
Electromagnetic Waves ◽  
Rapid Heating ◽  
Composite Films ◽  
Heating Rates ◽  
New Material ◽  
High Dielectric ◽  
First Time ◽  
Percolating Network

Abstract Here we report for the first time that Ti3C2Tx/polymer composite films rapidly heat when exposed to low-power radio frequency fields. Ti3C2Tx MXenes possess a high dielectric loss tangent, which is correlated with this rapid heating under electromagnetic fields. Thermal imaging confirms that these structures are capable of extraordinary heating rates (as high as 303 K/s) that are frequency- and concentration-dependent. At high loading (and high conductivity), Ti3C2Tx MXene composites do not heat under RF fields due to reflection of electromagnetic waves, whereas composites with low conductivity do not heat due to the lack of an electrical percolating network. Composites with an intermediate loading and a conductivity between 10–1000 S m−1 rapidly generate heat under RF fields. This finding unlocks a new property of Ti3C2Tx MXenes and a new material for potential RF-based applications.

scholarly journals Investigation of the relationship between optical auroral forms and HF radar E region backscatter

2000 ◽  
Vol 18 (6) ◽  
pp. 608-617 ◽  
Author(s):  
S. E. Milan ◽  
M. Lester ◽  
N. Sato ◽  
H. Takizawa ◽  
J.-P. Villain
Keyword(s):  
Spectral Characteristics ◽  
Hf Radar ◽  
Vhf Radar ◽  
The Past ◽  
Optical Signature ◽  
E Region ◽  
Coherent Backscatter ◽  
First Time ◽  
The Relationship ◽  
East West

Abstract. The SuperDARN HF radars have been employed in the past to investigate the spectral characteristics of coherent backscatter from L-shell aligned features in the auroral E region. The present study employs all-sky camera observations of the aurora from Husafell, Iceland, and the two SuperDARN radars located on Iceland, Þykkvibær and Stokkseyri, to determine the optical signature of such backscatter features. It is shown that, especially during quiet geomagnetic conditions, the backscatter region is closely associated with east-west aligned diffuse auroral features, and that the two move in tandem with each other. This association between optical and radar aurora has repercussions for the instability mechanisms responsible for generating the E region irregularities from which radars scatter. This is discussed and compared with previous studies investigating the relationship between optical and VHF radar aurora. In addition, although it is known that E region backscatter is commonly observed by SuperDARN radars, the present study demonstrates for the first time that multiple radars can observe the same feature to extend over at least 3 h of magnetic local time, allowing precipitation features to be mapped over large portions of the auroral zone.Key words: Ionosphere (particle precipitation; plasma waves and instabilities)

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