scholarly journals Dielectric Properties of BaTiO3–Epoxy Nanocomposites in the Microwave Regime

Polymers ◽  
2021 ◽  
Vol 13 (9) ◽  
pp. 1391
Author(s):  
Hsin-Yu Yao ◽  
Yi-Wen Lin ◽  
Tsun-Hsu Chang
Keyword(s):  
Dielectric Constant ◽  
Loss Tangent ◽  
Frequency Dispersion ◽  
Antireflection Coatings ◽  
Low Loss ◽  
Epoxy Nanocomposites ◽  
Maximum Dielectric Constant ◽  
High K ◽  
Theoretical Predictions ◽  
Microwave Regime

We synthesized BaTiO3–epoxy nanocomposites (particle size < 100 nm) with volume fractions up to 25 vol. %, whose high-frequency complex permittivity was characterized from 8.2 to 12.5 GHz. The maximum dielectric constant approaches 9.499 with an acceptable loss tangent of 0.113. The dielectric loss gradually saturates when the particle concentration is higher than 15 vol. %. This special feature is an important key to realizing high-k and low-loss nanocomposites. By comparing the theoretical predictions and the experimental data, four applicable effective-medium models are suggested. The retrieved dielectric constant (loss tangent) of 100-nm BaTiO3 nanopowder is in the range of 50–90 (0.1–0.15) at 8.2–12.5 GHz, exhibiting weak frequency dispersion. Two multilayer microwave devices—total reflection and antireflection coatings—are designed based on the fabricated nanocomposites. Both devices show good performance and allow broadband operation.

Dielectric Constant and Loss Tangent Characterization of Thin High-K Dielectrics Using Corner-to-Corner Plane Probing

2006 ◽  
Author(s):  
A. Ege Engin ◽  
Abdemanaf Tambawala ◽  
Madhavan Swaminathan ◽  
Swapan Bhattacharya ◽  
Pranabes Pramanik ◽  
...  
Keyword(s):  
Dielectric Constant ◽  
Loss Tangent ◽  
Dielectric Constant And Loss ◽  
High K

Prediction of Electrical Properties of Plain-Weave Fabric Composites for Printed Wiring Board Design

1993 ◽  
Vol 115 (2) ◽  
pp. 219-224 ◽  
Author(s):  
R. K. Agarwal ◽  
A. Dasgupta
Keyword(s):  
Dielectric Constant ◽  
Loss Tangent ◽  
Effective Properties ◽  
Mechanistic Model ◽  
Three Dimensional ◽  
Unit Cell ◽  
Woven Fabric ◽  
Effective Dielectric Constant ◽  
Low Loss ◽  
Dielectric Constant And Loss

A mechanistic model is presented for predicting the effective dielectric constant and loss tangent of woven-fabric reinforced composites with low-loss constituents. A two-scale asymptotic homogenization scheme is used to predict the orthotropic effective properties. A three-dimensional unit-cell enclosing the characteristic periodic repeat pattern in the fabric weave is isolated and modeled mathematically. Electrostatic boundary value problems (BVP’s) are formulated in the unit-cell and are solved analytically to predict effective dielectric constant of the composite, using three-dimensional series-parallel reactance nets. Results are also verified numerically, using finite element methods. The effective dielectric constant and the effective loss tangent are then obtained, analogous to mechanical viscoelastic problems for low-loss materials. The predicted dielectric constant and loss tangent are compared with experimental results for E-glass/epoxy laminates. Frequency dependence of the effective dielectric constant and loss tangent is obtained from the corresponding behavior of the constituent materials. Trade-off studies are conducted to investigate the effect of the constituent material properties on orthotropic effective dielectric permittivity.

MEASUREMENT OF THE DIELECTRIC PROPERTIES OF LOW LOSS MATERIALS AT MILLIMETER WAVELENGTHS

1958 ◽  
Vol 36 (12) ◽  
pp. 1672-1677
Author(s):  
A. G. Mungall
Keyword(s):  
Dielectric Constant ◽  
Dielectric Properties ◽  
Dielectric Loss ◽  
Loss Tangent ◽  
Dielectric Loss Tangent ◽  
Brewster Angle ◽  
Angle Of Incidence ◽  
Low Loss ◽  
Millimeter Wavelengths ◽  
Space Technique

Measurement at millimeter wavelengths of the dielectric properties of low loss materials by a free space technique is described. The dielectric constant is determined from the Brewster angle, and the dielectric loss tangent from the attenuation coefficient measured at the Brewster angle of incidence. Results are given for bakelite at wavelengths between 5 and 10 mm. Details of the instrument, which was specifically designed for these measurements, are also given.

scholarly journals Realization of trophy shaped flexible wearable antenna based on foam substrate

2018 ◽  
Vol 7 (2.12) ◽  
pp. 222
Author(s):  
Reema Dubey ◽  
Vinod Kumar Singh ◽  
Akash Kumar Bhoi ◽  
Zakir Ali
Keyword(s):  
Dielectric Constant ◽  
Reflection Coefficient ◽  
Loss Tangent ◽  
Low Dielectric Constant ◽  
Polystyrene Foam ◽  
Low Loss ◽  
Wearable Antenna ◽  
Low Dielectric ◽  
Large Bandwidth ◽  
Flexible Antenna

The endeavor of this paper is to analyze a light weighted flexible antenna for modern communication system. There are three different patch designs with operating frequency 4GHz. These proposed antennas are compact in size, shows high directivity and large bandwidth. Ex-pandable polystyrene foam is used as a substrate because such antenna are bendable, wearable, cheap, require less attention and having good features like low dielectric constant, low loss tangent and better efficiency. The antenna parameters like reflection coefficient, gain, band-width, radiation pattern are analyzed. The reflection coefficient of anticipated antenna provides a good concurrence between simulated and measured result. Foam based design is simulated by using CST studio. 

THE DIELECTRIC PROPERTIES OF SELECTED BASALTS

Geophysics ◽  
1973 ◽  
Vol 38 (1) ◽  
pp. 135-139 ◽  
Author(s):  
W. Hansen ◽  
W. R. Sill ◽  
S. H. Ward
Keyword(s):  
Dielectric Constant ◽  
Dielectric Properties ◽  
Loss Tangent ◽  
Room Temperature ◽  
Frequency Dispersion ◽  
Nitrogen Atmosphere ◽  
Frequency Range ◽  
Dielectric Constant And Loss ◽  
Identical Composition ◽  
Titanium Compounds

Basaltic samples of known chemical composition were measured for dielectric constant and loss tangent in the frequency range 100 hz to 50 Mhz. All samples were prepared and measured by a contact substitution method in a dry nitrogen atmosphere at room temperature. The measurements indicated a general spectrum of dielectric constant with a range of 10–65 at 100 hz to 7–15 at 50 Mhz with frequency dispersion observed to be minimal above 1 Mhz. The loss tangent decreases from a range .2–.9 at 100 hz to a range .02–.15 at 100 khz. A finer‐grained sample was observed to have higher dielectric properties below 1 Mhz than a coarser‐grained sample of identical composition. A qualitative and subsequent quantitative study of possible compositional effects indicated that iron‐titanium compounds may be responsible for observed variations in the dielectric spectra of typical basalts.

Dielectric Loss Measurements on Nonpolar Liquids in the Microwave Region from 18 to 37 GHz

1972 ◽  
Vol 50 (20) ◽  
pp. 2397-2401 ◽  
Author(s):  
I. R. Dagg ◽  
G. E. Reesor
Keyword(s):  
Dielectric Constant ◽  
Carbon Tetrachloride ◽  
Dielectric Loss ◽  
Carbon Disulfide ◽  
Loss Tangent ◽  
Microwave Frequency ◽  
Frequency Region ◽  
Low Loss ◽  
Microwave Region ◽  
Nonpolar Liquids

The results of dielectric-constant measurements on a number of low-loss liquids in the microwave frequency region from 18 to 40 GHz are presented. Emphasis is placed on the value of the loss tangent. Liquids measured include carbon tetrachloride, carbon disulfide, cyclohexane, n-hexane, n-heptane, n-nonane, and n-decane. A wave guide method was used giving an accuracy for the loss tangent of ±0.3 × 10−4. Where possible, results have been fitted to a Debye expression. Comparisons have been made with available results of other workers.

Off Axis Growth of Strontium Titanate Films with High Dielectric Constant Tuning and Low Loss

2002 ◽  
Vol 720 ◽  
Author(s):  
Satreerat Kampangkeaw ◽  
Charles T. Rogers
Keyword(s):  
Dielectric Constant ◽  
Dielectric Properties ◽  
Strontium Titanate ◽  
Loss Tangent ◽  
Figure Of Merit ◽  
High Dielectric Constant ◽  
Dielectric Films ◽  
Low Loss ◽  
Dielectric Constant And Loss ◽  
High Dielectric

AbstractWe have measured the nonlinear dielectric properties of strontium titanate (STO) thin films grown on neodymium gallate (NGO) and lanthanum aluminate (LAO) substrates. The films prepared by off-axis pulsed laser deposition were characterized by their dielectric constant and loss tangent at 1 MHz and 2 GHz, and from room temperature down to 4 K. The resulting films show significant variations of dielectric properties with position of the substrates with respect to the plume axis. STO films on LAO substrates show low loss and high dielectric constant in regions near the plume axis. On the other hand, STO on NGO shows this effect only on the films grown far from the plume axis. We also obtained a figure of merit from the relative variation of the dielectric constant divided by the loss tangent in the presence of a DC electric field up to +/- 4 V/μm. Careful mapping of the plume crossection allowed us to improve the quality and reproducibility of the dielectric films, obtaining a best figure of merit at 2 GHz and 4 K close to 100 for NGO substrate but only well off axis.

Dielectric Loss Measurements on Nonpolar Liquids in the Microwave Region 8 to 12 GHz

1974 ◽  
Vol 52 (1) ◽  
pp. 29-32 ◽  
Author(s):  
I. R. Dagg ◽  
G. E. Reesor
Keyword(s):  
Dielectric Constant ◽  
Carbon Tetrachloride ◽  
Dielectric Loss ◽  
Loss Tangent ◽  
Microwave Frequency ◽  
Frequency Region ◽  
Low Loss ◽  
Microwave Region ◽  
Nonpolar Liquids ◽  
Improved Accuracy

The results of dielectric-constant measurements on a number of low-loss liquids in the microwave frequency region from 8 to 12 GHz are reported. An improved wave-guide technique is described which gives precise values of the real part of the dielectric constant and improved accuracy in determining the dielectric loss. Liquids measured include the alkane series : n-pentane, n-hexane, n-heptane, n-nonane, n-decane, and n-dodecane. Results for cyclohexane and carbon tetrachloride are also given for comparison with those results of other workers. The data for the loss tangent for the alkane series of liquids are compared with previous results in the 18 to 37 GHz region.

Dielectric characteristics and diffuse ferroelectric phase transition in Sr4La2Ti4Nb6O30 tungsten bronze ceramics

2006 ◽  
Vol 21 (7) ◽  
pp. 1787-1792 ◽  
Author(s):  
X.L. Zhu ◽  
X.M. Chen ◽  
X.Q. Liu ◽  
Y. Yuan
Keyword(s):  
Phase Transition ◽  
Dielectric Constant ◽  
Ferroelectric Phase Transition ◽  
Ferroelectric Phase ◽  
Tungsten Bronze ◽  
Frequency Dispersion ◽  
Dielectric Characteristics ◽  
Low Dielectric ◽  
Dielectric Data ◽  
Maximum Dielectric Constant

In this work, Sr4La2Ti4Nb6O30 ceramics with tetragonal filled tungsten bronze structure were prepared, and the dielectric characteristics and ferroelectric transition were investigated. The room-temperature dielectric constant of the present ceramics showed very weak frequency dependency; it decreased from 570.4 to 561.7 when the frequency varied from 200 Hz to 1 MHz, and a comparatively low-dielectric loss was observed (in the order of 10−3). Unlike the situation for Ba4Ln2Ti4Nb6O30 (Ln = La, Nd and Sm), Sr4La2Ti4Nb6O30 ceramics showed a diffuse ferroelectric phase transition, and the diffuseness exponent γ was 1.61. Moreover, the obvious frequency dispersion was observed over a broad frequency range from 200 Hz to 1 MHz, and the maximum dielectric constant temperature Tmax shifted to higher temperatures with increasing frequency. The dielectric data agreed closely with the Vogel–Fulcher relationship. We concluded that tungsten bronze Sr4La2Ti4Nb6O30 has the relaxor ferroelectric nature.

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