ZnO-Nb2O5-TiO2 Dielectric Resonators and Porosity Influence on Dielectric Constant Values

The dielectric resonator (DR) is a ceramic component used in electronic circuits that can operate in microwave frequency range, where it plays the role of resonant element and enables the construction of high selective filters and oscillators. The dielectric properties of a ceramic resonator are influenced by their microstructure characteristics as pores amount. This work shows a study of the influence of pores amount (porosity) on the dielectric constant values of ceramics from ZnO-Nb2O5-TiO2 system. Mixtures of Nb2O5, ZnO, and TiO2 powders were compacted by uniaxial (100 MPa) and isostatic (300 MPa) pressing and sintered at 1100, 1200, and 1250°C. The experimental dielectric constant values of the sintered ceramics were corrected to eliminate the porosity influence. The results showed that the porosity, the type and quantities of crystalline chemical compounds in the ceramics influence the dielectric constant values.

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The Analysis of Dielectric Constant, Loss Factor and Q-Factor of Selected Fruits at Microwave Frequency Range

Journal of Scientific Research and Reports ◽

10.9734/jsrr/2020/v26i830295 ◽

2020 ◽

pp. 57-66

Author(s):

J. T. Ikyumbur ◽

A. A. McAsule ◽

N. S. Akiiga ◽

Z. E. Andrawus ◽

S. T. Kungur

Keyword(s):

Dielectric Constant ◽

Dielectric Loss ◽

Loss Factor ◽

Microwave Frequency ◽

Dielectric Loss Factor ◽

Q Factor ◽

Frequency Range ◽

Temperature Changes ◽

Problem Solving Environment ◽

Lower Frequencies

The dielectric constant, dielectric loss factor and Q-Factor of orange, red and green apples were studied at Microwave frequency range. An algorithm was written using the Debye equations and the interactive problem-solving environment of Maple-18 was used to generate results for the dielectric constant, loss factor and quality factor. The variation in the dielectric constant, loss factor and Q-factor as both frequency and temperature changes respectively within and range were shown graphically. The dielectric constant of all the fruits were higher at lower frequencies, it then decreases continuously as frequency increases. On the other hand, the loss factor of this fruits were small at lower frequencies but increased to its peak before decreasing continuously for all temperatures. Interestingly, the fruits’ Q-Factor were higher at lower frequencies and temperatures but decreases rapidly as the frequency increases. The contribution of the space charge, orientation, ionic and electronic polarizations to the dielectric constant, dielectric loss factor and Q-Factor of these fruits at lower frequency and higher frequency were discussed. The effect of the excess sugar and water content on the dielectric constant, loss factor and Q-Factor attributed to the appearance of vibrational peaks was also discussed. This work hereby provides a guidance in developing new microwave processes.

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Dielectric Studies of Admicelled Natural Rubber with Poly(3-Trimethoxysilylpropyl Methacrylate)

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.844.373 ◽

2013 ◽

Vol 844 ◽

pp. 373-376

Author(s):

Suparat Nooma ◽

Rathanawan Magaraphan

Keyword(s):

Dielectric Constant ◽

Composite Materials ◽

Dielectric Properties ◽

Chemical Modification ◽

Natural Rubber ◽

Microwave Frequency ◽

Dielectric Studies ◽

Frequency Range ◽

Admicellar Polymerization ◽

Methoxy Groups

In this work, 3-trimethoxysilylpropyl methacrylate (MPS) was used as a substrate for coating on natural rubber (NR) particles by admicellar polymerization. The incorporation of MPS monomer, consisting of silicon element and 3 reactive methoxy groups (R-Si(OCH3)), is expected to increase dielectric properties of NR. Under the admicellar polymerization, the R-Si(OCH3) groups can be hydrolyzed and condensed into polysiloxane existed on NR particles. This method aims to prepare composite materials from NR and MPS with various amounts of MPS. The effects of microwave frequency and chemical modification by admicellar polymerization were studied. The dielectric properties of admicelled natural rubber (adNR) with PMPS were investigated at 20 °C in a frequency range extended from MHz to GHz. The results showed that the dielectric constant of adNR increased with PMPS contents. To study the effect of crosslinking on the dielectric properties of adNR, the dielectric spectroscopy measurements were performed on prevulcanized and non-prevulcanized adNR. The investigation showed that the dielectric constant of non-prevulcanized adNR was less than prevulcanized adNR.

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Dielectric Studies of Binary Mixtures of 1-Propanol and Fluorobenzene

Solid State Phenomena ◽

10.4028/www.scientific.net/ssp.209.203 ◽

2013 ◽

Vol 209 ◽

pp. 203-206 ◽

Cited By ~ 1

Author(s):

Ashvin N. Prajapati ◽

Vipinchandra A. Rana ◽

A.D. Vyas ◽

S.P. Bhatanagar ◽

D.H. Gadani

Keyword(s):

Dielectric Constant ◽

Binary Mixtures ◽

Complex Permittivity ◽

High Frequency ◽

Low Frequency ◽

Microwave Frequency ◽

Static Dielectric Constant ◽

Frequency Range ◽

Optical Dielectric Constant ◽

Optical Dielectric

Complex permittivity spectra of 1-Propanol (1-PrOH), Fluorobenzene (FB) and their binary mixtures are obtained in radio and microwave frequency range using Vector network analyzer (VNA) operating in the frequency range 0.3 MHz to 3.0 GHz and standard microwave benches operated at 9.1 GHz and 19.61 GHz. Static dielectric constant (ε0) and high frequency limiting dielectric constant (ε∞1) for binary mixtures of 1-PrOH and FB are obtained by extrapolating the complex permittivity data towards low frequency side and high frequency side on complex plane plots. Optical dielectric constant (ε∞ = n2) for binary mixtures are measured using Abbe's refractometer. Excess static dielectric constant (ε0)E, Kirkwood correlation parameters (g, geff and gf) and Bruggeman factor (fB) are determined from the values of static dielectric constant (ε0) and optical dielectric constant (ε∞). These parameters have been discussed to explore the molecular interaction between the molecular species.

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Dielectric Properties of SiAlON Ceramics

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.403.125 ◽

2008 ◽

Vol 403 ◽

pp. 125-128 ◽

Cited By ~ 3

Author(s):

Do Kyung Kim ◽

Ha Neul Kim ◽

Young Hoon Seong ◽

Seung Soo Baek ◽

Eul Son Kang ◽

...

Keyword(s):

Dielectric Constant ◽

Dielectric Properties ◽

Room Temperature ◽

Microwave Frequency ◽

Tangent Loss ◽

Hot Press ◽

Frequency Range ◽

Cationic Species ◽

Press Method ◽

Resonator Method

The dielectric properties of -SiAlON and various cations doped -SiAlON bulk ceramics prepared by a hot-press method were investigated. The dielectric properties (dielectric constant and tangent loss) were characterized by a post-resonator method (Hakki-Coleman method) at room temperature in the microwave frequency range. The effect of z-values about -SiAlON was examined, and also the effects of various interstitial cations on dielectric properties of -SiAlON were studied. Dielectric properties of -SiAlON were compared with those of Si3N4 and -SiAlON and their relationship between the dielectric properties and the cationic species of SiAlON were discussed.

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Bi2O3-Modified Ceramics Based on BaTiO3 Powder Synthesized in Water Vapor

Inorganics ◽

10.3390/inorganics8020008 ◽

2020 ◽

Vol 8 (2) ◽

pp. 8 ◽

Cited By ~ 3

Author(s):

Anastasia Kholodkova ◽

Aleksey Smirnov ◽

Marina Danchevskaya ◽

Yurii Ivakin ◽

Galina Muravieva ◽

...

Keyword(s):

Dielectric Constant ◽

Water Vapor ◽

Dielectric Properties ◽

Room Temperature ◽

Frequency Range ◽

Batio3 Powder ◽

Strength Determination ◽

Water Vapor Atmosphere ◽

Room Temperature Dielectric Constant

Bi2O3 was investigated in the role of a modifier for BaTiO3 powder synthesized in a water vapor atmosphere at 200 °C and 1.55 MPa. Modification was aimed at increasing the sinterability of the powder as well as improving the structural and dielectric properties of the obtained ceramics. The morphology and phase contents of the synthesized BaTiO3 powder were controlled by the methods of SEM and XRD. Properties of pure and Bi-doped BaTiO3 ceramics were comprehensively studied by XRD, SEM, dielectric spectroscopy, and standard approaches for density and mechanical strength determination. Doping with Bi2O3 favored BaTiO3 ceramic densification and strengthening. The room-temperature dielectric constant and the loss tangent of Bi-doped BaTiO3 were shown to stabilize within the frequency range of 20 Hz to 2 MHz compared to non-doped material. The drop of dielectric constant between room temperature and Curie point was significantly reduced after Bi2O3 addition to BaTiO3. Bi2O3 appeared to be an effective modifier for BaTiO3 ceramics produced from non-stoichiometric powder synthesized in water vapor.

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CANDIDATES FOR μ<0, ∊<0 NANOSTRUCTURES

International Journal of Modern Physics B ◽

10.1142/s0217979201007592 ◽

2001 ◽

Vol 15 (24n25) ◽

pp. 3258-3265 ◽

Cited By ~ 23

Author(s):

G. DEWAR

Keyword(s):

Magnetic Field ◽

Dielectric Constant ◽

Composite Materials ◽

Applied Magnetic Field ◽

Microwave Frequency ◽

Index Of Refraction ◽

Frequency Range ◽

Left Handed ◽

Negative Index Of Refraction ◽

Recent Interest

Recent interest has been generated in composite materials for which both the dielectric constant and the magnetic permeability are negative. These composites behave as if they possess a negative index of refraction, although the broader, less specific adjective "left-handed" has also been applied to them. Such composites possess two sets of structures which are separately responsible for the negative ∊ and μ. However, materials having a negative μ are common in the microwave frequency range and such a material can replace one set of structures in the composite. An example of a simple composite is a YIG medium (μ<0) penetrated by sets of metallic strips or wires which give rise a negative dielectric constant in the appropriate frequency range. The index of refraction of the composite can be modulated by adjusting the applied magnetic field.

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RCS Enhancement of Dielectric Resonator Tag Using Spherical Lens

Frequenz ◽

10.1515/freq-2018-0224 ◽

2019 ◽

Vol 73 (5-6) ◽

pp. 161-170 ◽

Cited By ~ 5

Author(s):

Ali Alhaj Abbas ◽

Mohammed El-Absi ◽

Ashraf Abuelhaija ◽

Klaus Solbach ◽

Thomas Kaiser

Keyword(s):

Dielectric Resonator ◽

Indoor Localization ◽

Fourth Power ◽

Dielectric Resonators ◽

Frequency Range ◽

Spherical Lens ◽

Localization System ◽

Lens Diameter ◽

Lens Surface ◽

Lens Radius

Abstract The RCS of flat cylindrical Dielectric Resonators (DR) is investigated and found to be too low for an application of the resonators as tags in a novel indoor localization system at mm-wave frequencies. As a method to increase the RCS of a DR tag, we propose the combination with a constant-index spherical lens. The collimation and scattering properties of this lens type are found suitable for a combination with DRs. The optimum relative permittivity of the lens is found in the range of ϵr=1.6 to 2.8 and the optimum distance between lens surface and DR is found slightly larger than the radius of the DR. RCS enhancement is found to vary with the modes of the DR but increases approximately with the fourth power of the lens radius. However, RCS signatures become corrupted by scattering due to mismatch effects of large lenses such that the lens diameter has to be limited to 4 to 5 wavelengths with the RCS enhancement limited to about 30 to 35 dB. Simulation and experimental verification are performed at a down-scaled frequency range from 4 GHz to 7 GHz using lenses of 60 mm and 120 mm diameter made of paraffin wax.

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