Estimating the Permittivity of Solids from Measurements on Granular or Pulverized Materials

1988 ◽  
Vol 124 ◽  
Author(s):  
Stuart O. Nelson
Keyword(s):  
Dielectric Constant ◽  
Bulk Density ◽  
Complex Permittivity ◽  
Loss Factor ◽  
Solid Materials ◽  
White Rice ◽  
Particle Mixture ◽  
Dielectric Constant And Loss

ABSTRACTA procedure is outlined for determining the complex permittivity components of solid materials of known densities from those properties of granular or pulverized samples measured at a few different bulk densities. Properties of the solid are obtained by extrapolation of functions of the dielectric constant and loss factor that are linearly related to the bulk density of the air-particle mixture. Examples are given for whole-kernel wheat, ground white rice, and pulverized goethite.

Dielectric Properties Measurements and Data

1990 ◽  
Vol 189 ◽  
Author(s):  
Joseph A. Carpenter
Keyword(s):  
Dielectric Constant ◽  
Dielectric Properties ◽  
Loss Factor ◽  
Intelligent Design ◽  
Elevated Temperatures ◽  
Measurement Techniques ◽  
Materials Processing ◽  
Microwave Range ◽  
Solid Materials ◽  
Dielectric Constant And Loss

ABSTRACTThis paper reviews measurement techniques and sources of data for the dielectric constant and loss factor of solid materials. Accurate values of such properties are basic to intelligent design of materials processing schemes utilizing electromagnetic energy. Emphasis is on techniques and data for these properties in the “microwave” range of frequencies of roughly 108 to 1011 Hz and at elevated temperatures.

Microwave Nondestructive Sensing of Moisture Content and Water Activity of Almonds

2021 ◽  
Vol 64 (4) ◽  
pp. 1373-1379
Author(s):  
Samir Trabelsi
Keyword(s):  
Dielectric Constant ◽  
Dielectric Properties ◽  
Dielectric Loss ◽  
Moisture Content ◽  
Bulk Density ◽  
Water Activity ◽  
Free Space ◽  
Loss Factor ◽  
Dielectric Loss Factor ◽  
List Type

HighlightsMoisture and water activity were determined nondestructively and in real time from measurement of dielectric properties.Moisture and water activity calibration equations were established in terms of the dielectric properties.Situations in which bulk density was known or unknown were considered.SEC ranged from 0.41% to 0.68% for moisture and from 0.02 to 0.04 for water activity.Abstract. A method for rapid and nondestructive determination of moisture content and water activity of granular and particulate materials was developed. The method relies on measurement of the dielectric constant and dielectric loss factor at a single microwave frequency. For the purpose of illustration, the method was applied to predicting the moisture content and water activity of almond kernels. A free-space transmission technique was used for accurate measurement of the dielectric properties. Samples of Bute Padre almond kernels with moisture content ranging from 4.8% to 16.5%, wet basis (w.b.), and water activity ranging from 0.50 to 0.93 were loaded into a Styrofoam sample holder and placed between two horn-lens antennas connected to a vector network analyzer. The dielectric properties were calculated from measurement of the attenuation and phase shift at 8 GHz and 25°C. The dielectric properties increased linearly with moisture content, while they showed an exponential increase with water activity. Situations in which the bulk density was known and unknown were considered. Linear and exponential growth regressions provided equations correlating the dielectric properties with moisture content and water activity with coefficients of determination (r2) higher than 0.96. Analytical expressions of moisture content and water activity in terms of the dielectric properties measured at 8 GHz and 25°C are provided. The standard error of calibration (SEC) was calculated for each calibration equation. Results show that moisture content can be predicted with SECs ranging from 0.41% to 0.68% (w.b.) and water activity with SECs ranging from 0.02 to 0.04 for almond kernel samples with water activity ranging from 0.5 to 0.9 and moisture contents ranging from 4.8% to 16.5% (w.b.). Keywords: Bulk density, Dielectric constant, Dielectric loss factor, Free-space measurements, Loss tangent, Microwave frequencies, Moisture content, Water activity.

scholarly journals The Effects of SLS on Structural and Complex Permittivity of SLS-HDPE Composites

2019 ◽  
Vol 2019 ◽  
pp. 1-7
Author(s):  
Abubakar Dantani Meli ◽  
Zulkifly Abbas ◽  
Mohd Hafiz Mohd Zaid ◽  
Nor Azowa Ibrahim
Keyword(s):  
Dielectric Constant ◽  
Complex Permittivity ◽  
Loss Factor ◽  
Microwave Frequency ◽  
Soda Lime ◽  
Physical Structure ◽  
Host Matrix ◽  
Lower Dielectric Constant ◽  
Absorbing Material ◽  
Diffraction Patterns

RS-4050 is a rigid epoxy based magnetic castable microwave absorbing material; it has been used in many areas of waveguide application as a microwave waveguide terminations and dummy loads. In recent years, there is a demand for composites material with lower dielectric constant higher loss factor for microwave application. This research, the effect of soda lime silica (SLS) on structural and complex permittivity of soda lime silica-high density polyethylene (SLS-HDPE) composites was conducted in order to explore the possibility of substituting RS-4050 with SLS-HDPE composites as a microwave waveguide terminations and dummy loads. Elemental weight composition of the SLS glass powder and HDPE was identified through scaling of different percentage of SLS and HDPE. X-ray diffraction (XRD) was used to investigate the crystallinity behavior of SLS-HDPE composites. The proposed SLS-HDPE composites material was studied at frequencies 8 to 12 GHz. The study was conducted using waveguide Agilent N5230A PNA technique. The effect of microwave frequency on complex permittivity properties for SLS-HDPE composites of different percentages of SLS and HDPE (10% SLS-90% HDPE, 20% SLS-80% HDPE, 30% SLS-70% HDPE, 40% SLS-60% HDPE, and 50% SLS-50% HDPE) were investigated. Results showed the diffraction patterns reveal good amorphous quality with a genuinely properties structure. The microwave frequency and composites percentages significantly influenced the complex permittivity (real and imaginary) properties of the composites. Moreover, the complex permittivity increased as the percentage of SLS filler increased in the host matrix HDPE as a result of increased in composite density due to less volume being occupied by the filler as the percentage increased. The complex permittivity of the smallest and largest percentages of SLS (10% and 50%) was (2.67-j0.05) and (3.45-j0.35), respectively. The study revealed that the best sample for waveguide application as microwave terminator is 50% SLS as it has the highest dielectric constant, highest loss factor, and highest loss tangent as compared to 10% SLS to 40% SLS. Also 50% SLS has the highest absorption properties as compare to 10% SLS, 20% SLS, 30% SLS, or 40% SLS. The XRD physical structure of the SLS-HDPE composites revealed the absorption characteristics of different percentages of the materials. The SLS-HDPE composites can be applied in the area of waveguide as a microwave waveguide terminations and dummy loads.

scholarly journals An Experimental Study on the Dielectric Properties of Rubber Materials

Polymers ◽  
2021 ◽  
Vol 13 (17) ◽  
pp. 2908
Author(s):  
Hailong Chen ◽  
Yudong Xu ◽  
Mengqi Liu ◽  
Tao Li
Keyword(s):  
Experimental Study ◽  
Dielectric Constant ◽  
Dielectric Properties ◽  
Loss Factor ◽  
Peak Frequency ◽  
Mixing Process ◽  
Absorption Properties ◽  
Microwave Absorption Properties ◽  
Internal Mixing ◽  
Dielectric Constant And Loss

According to specific formulas, the mixing of rubber samples occurs by two methods: open mixing and internal mixing. The effects of frequency, mixing process, carbon black (CB) content, zinc oxide (ZnO) content, and stearic acid (SA) content on the dielectric properties of rubber materials were studied. The results showed that the effects of the mixing process on the dielectric properties of the rubber samples cannot be ignored, and the appropriate mixing process should be selected when preparing the required rubber materials. The dielectric constant and loss factor of the rubber samples vary depending on the frequency. The dielectric constant had a peak and valley value, while the loss factor only had a peak. The dielectric constant and loss factor of rubber samples were significantly affected by the content of CB, ZnO, and SA. The peak frequency decreased with the increase in CB content, however, the dielectric constant increased with an increase in CB content. The higher the ZnO content, the lower the peak frequency. In addition, the dielectric constant and loss factor increased with an increase in ZnO content. The higher the SA content, the greater the peak frequency. In addition, the dielectric constant and loss factor decreased with an increase in SA content. It is hoped that the experimental results obtained can provide guidance for the study of the dielectric properties, microwave absorption properties, and microwave heating characteristics of rubber polymers.

scholarly journals Computation of Dielectric constant and loss factor of 1-ethyl-3-methylimidazolium chloride (emim)

2020 ◽  
Vol 7 (1) ◽  
pp. 110-116
Author(s):  
Lubis Satzen ◽  
Samson D. Yusuf ◽  
Abdulmumini Z. Loko ◽  
Lucas W. Lumbi
Keyword(s):  
Dielectric Constant ◽  
Loss Factor ◽  
Dielectric Constant And Loss

scholarly journals Comparative Study of Complex-Ratio-Measuring Circuits and Coaxial Probe in Diagnosis of Breast Tumors

2021 ◽  
Author(s):  
Nadera Najib ◽  
Kok Yeow You ◽  
Mauricio Perez ◽  
Robin Augustine
Keyword(s):  
Dielectric Constant ◽  
Phase Shift ◽  
Reflection Coefficient ◽  
Loss Factor ◽  
Breast Tissue ◽  
Standard Technique ◽  
Diagnostic Purpose ◽  
Tissue Samples ◽  
Dielectric Constant And Loss ◽  
Breast Tissues

A developed six-port reflectometry (SPR) system was integrated to measure the relative permittivity of tumor and normal breast tissue for medical diagnostic purpose. In order to obtain an accurate and precise measurement, the calibration process was done to the SPR using the well-known three-standard technique. Next, the studied dielectric probe was connected to the calibrated measurement-port of the SPR. The open end of the probe aperture was dibbed into the normal and tumor synthetic breast tissue samples to measure the synthetic breast tissues dielectric constant, ɛrʹ, and loss factor, ɛrʺ in the frequency range of 1.5 GHz to 3.3 GHz. Finally, the comparative studies were conducted between commercial VNA with Keysight 85070E dielectric probe and the studied SPR-probe system based on the measured magnitude of the reflection coefficient, phase shift, dielectric constant, and loss factor of the synthetic breast samples. The maximum absolute errors of the measured reflection coefficient magnitude, phase shift, dielectric constant, and loss factor were found to be 0.01, 1.07°, 1.12, and 0.75, respectively. It was ascertained that the predicted dielectric constant, ɛrʹ, is able to differentiate between normal, (ɛrʹ < 50) and tumor, (ɛrʹ > 50) breast tissues.

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