scholarly journals Resonator Method for Studying Dielectric Characteristics of Сaustobiolithes

2021 ◽  
Vol 14 (3) ◽  
pp. 315-324
Author(s):  
Vladimir V. Parshin ◽  
◽  
Evgeniy A. Serov ◽  
Dmitriy I. Sobolev ◽  
Tatiana O. Krapivnitskaia ◽  
...  
Keyword(s):  
Refractive Index ◽  
Organic Materials ◽  
Microwave Processing ◽  
Frequency Range ◽  
Dielectric Parameters ◽  
Dielectric Characteristics ◽  
Measurement Results ◽  
Resonator Method ◽  
Thz Range

For the sub-THz range, a method for studying the electrodynamic characteristics of organic materials – caustobiolithes-is developed on the basis of a resonator spectrometer. In the frequency range 110 ÷ 260 GHz, the dielectric parameters (refractive index n and tanδ) of peat powders after its microwave processing in the process of «soft» pyrolysis, as well as core sections of oil-containing rock, were studied. The influence of natural humidity on the dielectric parameters of the samples is considered. The reasons for the spread of measurement results, which is observed in these materials and is their specific feature, are discussed

scholarly journals Analysis of the temperature-frequency effect on dielectric losses in a grain medium

2022 ◽  
Vol 25 (6) ◽  
pp. 733-740
Author(s):  
M. Yu. Buzunova
Keyword(s):  
Dielectric Loss ◽  
Electric Field ◽  
Mechanical Activation ◽  
External Electric Field ◽  
Loss Tangent ◽  
Dielectric Loss Tangent ◽  
Dielectric Losses ◽  
Frequency Range ◽  
Dielectric Parameters ◽  
Dielectric Characteristics

The aim of the study is to determine the influence of the thermal effect on dielectric losses in grain mass subject to bruising during drying and storage on the example of wheat across a wide external electric field frequency range. The study of the electrophysical characteristics of a dispersed medium comprising mechanically activated wheat grains takes into account the effect of the degree of breakage on the dielectric parameters of the studied medium. The studies were carried out on experimental samples having different degrees of mechanical activation of particles, which ranged in size from from 50 to 1000 μm. Variations in the dielectric loss tangent were studied using the dielectric method across a wide temperature-frequency range. Studies of variations in dielectric properties were carried out for wheat sam-ples subjected to grinding according to the mechanical activation method at temperatures varying from 20°C to 255°C with a constant heating rate of 0.7 deg / min. During the course of the experiment, the frequency of the external electric field was varied from 25 Hz to 1∙106 Hz. Dielectric constant and dielectric loss tangent calculations were carried out using data on electrical capacity and conductivity obtained using an E7-20 immittance meter and a measuring cell in the form of a flat capacitor. An analysis of variations in these dielectric characteristics was also performed. The obtained stable correlation of the dielectric loss tangent with the frequency of external electric impact and the degree of heating of the samples was most pronounced for finely dispersed samples (particle size 50 μm). Variations in dielectric characteristics are most significant when the frequency decreases to 100 Hz and below. The study of variations in the main dielectric parameters can be used to prevent self-heating and ignition of the grain mass during storage, as well as for selecting the most efficient energy-saving drying mode.

scholarly journals Broadband spectroscopy of astrophysical ice analogues

2019 ◽  
Vol 629 ◽  
pp. A112 ◽  
Author(s):  
B. M. Giuliano ◽  
A. A. Gavdush ◽  
B. Müller ◽  
K. I. Zaytsev ◽  
T. Grassi ◽  
...  
Keyword(s):  
Refractive Index ◽  
Optical Properties ◽  
Time Domain ◽  
Complex Refractive Index ◽  
Far Infrared ◽  
Infrared Region ◽  
Thz Radiation ◽  
The Real ◽  
Thz Range ◽  
The Time Domain

Context. Reliable, directly measured optical properties of astrophysical ice analogues in the infrared and terahertz (THz) range are missing from the literature. These parameters are of great importance to model the dust continuum radiative transfer in dense and cold regions, where thick ice mantles are present, and are necessary for the interpretation of future observations planned in the far-infrared region. Aims. Coherent THz radiation allows for direct measurement of the complex dielectric function (refractive index) of astrophysically relevant ice species in the THz range. Methods. We recorded the time-domain waveforms and the frequency-domain spectra of reference samples of CO ice, deposited at a temperature of 28.5 K and annealed to 33 K at different thicknesses. We developed a new algorithm to reconstruct the real and imaginary parts of the refractive index from the time-domain THz data. Results. The complex refractive index in the wavelength range 1 mm–150 μm (0.3–2.0 THz) was determined for the studied ice samples, and this index was compared with available data found in the literature. Conclusions. The developed algorithm of reconstructing the real and imaginary parts of the refractive index from the time-domain THz data enables us, for the first time, to determine the optical properties of astrophysical ice analogues without using the Kramers–Kronig relations. The obtained data provide a benchmark to interpret the observational data from current ground-based facilities as well as future space telescope missions, and we used these data to estimate the opacities of the dust grains in presence of CO ice mantles.

Active modulation of refractive index by stress in the terahertz frequency range

2013 ◽  
Vol 52 (25) ◽  
pp. 6364 ◽  
Author(s):  
Lin’an Li ◽  
Wei Song ◽  
Zhiyong Wang ◽  
Shibin Wang ◽  
Mingxia He ◽  
...  
Keyword(s):  
Refractive Index ◽  
Terahertz Frequency ◽  
Frequency Range ◽  
Terahertz Frequency Range

Long-wavelength lattice vibrations of Ag3In5Se9 and Ag3In5Te9 single crystals — An inversion of LO- and TO-mode frequencies

2016 ◽  
Vol 30 (18) ◽  
pp. 1650229 ◽  
Author(s):  
Nizami Mamed Gasanly
Keyword(s):  
Refractive Index ◽  
Single Crystals ◽  
Longitudinal Optical ◽  
Absorption Index ◽  
Energy Losses ◽  
Optical Parameters ◽  
Lattice Vibrations ◽  
Frequency Range ◽  
Long Wavelength ◽  
Optical Modes

Infrared (IR) reflectivities are registered in the frequency range of 50–2000 cm[Formula: see text] for Ag3In5Se9 and Ag3In5Te9 single crystals grown by Bridgman method. Three infrared-active modes are detected in spectra. The optical parameters, real and imaginary parts of the dielectric function, the function of energy losses, refractive index, absorption index and absorption coefficient were calculated from reflectivity experiments. The frequencies of transverse and longitudinal optical modes (TO and LO modes) and oscillator strength were also determined. The bands detected in infrared spectra were tentatively attributed to various vibration types (valence and valence-deformation). The inversion of LO- and TO-mode frequencies of the sandwiched pair was observed for studied crystals.

scholarly journals Design of Broadband Compact Canonical Triple-Sleeve Antenna Operating in UHF Band

2021 ◽  
Vol 21 (4) ◽  
pp. 291-298
Author(s):  
Chandana SaiRam ◽  
Damera Vakula ◽  
Mada Chakravarthy
Keyword(s):  
Wireless Communication ◽  
Instantaneous Frequency ◽  
Dipole Antenna ◽  
Frequency Range ◽  
Broadband Antenna ◽  
Operating Frequency Range ◽  
Half Wave ◽  
Measurement Results ◽  
Antenna Configuration ◽  
Good Agreement

In this paper, a novel compact broadband antenna at UHF frequencies is presented with canonical shapes. Hemispherical, conical and cylindrical shapes have all been considered for antenna configuration. The designed antenna provides an instantaneous frequency range from 370 to 5,000 MHz with omnidirectional characteristics. The antenna was simulated in CST Microwave Studio, fabricated and evaluated; the results are presented. The simulated and measurement results are in good agreement. The antenna has voltage standing wave ratio (VSWR) ≤ 1.9:1 in 400–570 MHz, 2,530–3,740 MHz and 4,180–4,620 MHz; it has VSWR ≤ 3:1 over the operating frequency range 370–5,000 MHz and the measured gain varies from -0.6 to 4.5 dBi over the frequency band. The concept of canonical-shaped antenna elements and the incorporation of triple sleeves resulted in a reduction of the length of the antenna by 62% compared to the length of a half-wave dipole antenna designed at the lowest frequency. The antenna can be used for trans-receiving applications in wireless communication.

scholarly journals Study and Simulation of a Sensor Based on 2D Photonic Crystals for the Detection of Aromatic Compounds: C6H5I, C6H5F and C6H5Cl

2021 ◽  
Vol 45 (4) ◽  
pp. 335-339
Author(s):  
Mehdi Ghoumazi ◽  
Messaoud Hameurlain
Keyword(s):  
Refractive Index ◽  
Energy Density ◽  
Photonic Crystals ◽  
Ring Resonator ◽  
Organic Materials ◽  
Simulation Software ◽  
Dielectric Constants ◽  
Total Energy Density ◽  
Materials Used ◽  
Comsol Simulation

A new study was presented on a new sensor based on two-dimensional photonic crystals (Phc's) to detect the following three organic materials: iodobenzene (C6H5I), fluorobenzene (C6H5F), chlorobenzene (C6H5Cl). These materials have dielectric constants (εr) equal to 2.623; 2.140; 2.318, respectively. The proposed sensor is a structure made of silicon rods submerged in air plus a ring resonator. The ring resonator is stuck between two horizontal waveguides. At the end of the ends of the structure there are four ports where port 1 and 2 belong to the top guide and port (3) and (4) the bottom one. In order to analyze the behavior of the sensor, a plane wave expansion approach (PWE) and the finite element method (FEM) are applied. Thanks to the MATLAB and COMSOL simulation software, we were able to obtain the following numerical results: the norm of the electric field, the total energy density and this last magnitude according to the refractive indices of the different organic materials used. We could observe variations in energy density for each material. So, this change is due to their refractive index which varies from one material to another. In this study, we have fixed the other parameters like the constant of the lattice "a" and the radius "r" and we are interested in the dielectric constants (εr) or more precisely the refractive index (n), the latter proves that it is one of the important parameters for detection.

scholarly journals Studying of dielectric spectra of YCu0.15Mn0.85O3 solid solution with the use of complex conductivity

2021 ◽  
pp. 2160013
Author(s):  
A. V. Nazarenko ◽  
A. V. Pavlenko ◽  
Y. I. Yurasov
Keyword(s):  
Solid Solution ◽  
Electrical Conductivity ◽  
Model Description ◽  
Complex Conductivity ◽  
Electrophysical Properties ◽  
Approximation Model ◽  
Frequency Range ◽  
Dielectric Parameters ◽  
Frequency Behavior ◽  
Complex Electrical Conductivity

This work presents the results of studying the electrophysical properties of the YCu[Formula: see text]Mn[Formula: see text]O3 solid solution in the range of temperatures of [Formula: see text] = 26–400[Formula: see text]C and frequency range of [Formula: see text] = 102–105 Hz. A model description of the revealed dispersion of dielectric parameters in the material is made. The nonclassical modified Havriliak–Negami model written for complex electrical conductivity was used as an approximation model. It is shown that the application of this model almost exactly describes the frequency behavior of the dielectric constant [Formula: see text]/[Formula: see text], the dielectric loss tangent tg[Formula: see text] as well as the real and imaginary parts of complex conductivity [Formula: see text] and [Formula: see text]. The results of this work are an important step in identifying the opportunities and understanding the applications of this model.

Spatial resonances of the Cherenkov emission in dispersive metamaterials

2013 ◽  
Vol 1617 ◽  
pp. 181-185
Author(s):  
Gennadiy Burlak ◽  
Erika Martinez-Sanchez
Keyword(s):  
Refractive Index ◽  
Spatial Structure ◽  
Frequency Domain ◽  
Frequency Spectrum ◽  
Specific Interaction ◽  
Optical Emission ◽  
Frequency Range

ABSTRACTWe systematically study the Cherenkov optical emission by a nonrelativistic modulated source crossing 3D dispersive metamaterial. It is found that the interference of the field produced by the modulated source with the periodic plasmonic-polariton excitations leads to the specific interaction in the frequency range where the dispersive refractive index of a metamaterial is negative. Such resonance considerably modifies the spatial structure of the Cherenkov fieldand the reversed Cherenkov emission. In our study parameters of metamaterial and modulated source are fixed while the frequency spectrum of the plasmonic excitations is formed due to the fields interplay in the frequency domain.

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