scholarly journals Computational and Experimental Approaches for Determining Scattering Parameters of OPEFB/PLA Composites to Calculate the Absorption and Attenuation Values at Microwave Frequencies

Polymers ◽  
2020 ◽  
Vol 12 (9) ◽  
pp. 1919
Author(s):  
Ahmad Fahad Ahmad ◽  
Sidek Hj Ab Aziz ◽  
Zulkifly Abbas ◽  
Daw Mohammad Abdalhadi ◽  
Ahmad Mamoun Khamis ◽  
...  
Keyword(s):  
Dielectric Constant ◽  
Transmission Line ◽  
Polylactic Acid ◽  
Oil Palm ◽  
Loss Factor ◽  
Empty Fruit Bunch ◽  
Absorption Loss ◽  
Microstrip Transmission Line ◽  
Microwave Frequencies ◽  
Commercial Software Package

This article describes attenuation and absorption measurements using the microstrip transmission line technique connected with a microwave vector network analyzer (Agilent 8750B). The magnitudes of the reflection (S11) and transmission (S21) coefficients obtained from the microstrip transmission line were used to determine the attenuation and absorption of oil palm empty fruit bunch/polylactic acid (OPEFB/PLA) composites in a frequency range between 0.20 GHz and 12 GHz at room temperature. The main structure of semi-flexible substrates (OPEFF/PLA) was fabricated using different fiber loading content extracted from oil palm empty fruit bunch (OPEFB) trees hosted in polylactic acid (PLA) using the Brabender blending machine, which ensured mixture homogeneity. The commercial software package, Computer Simulation Technology Microwave Studio (CSTMWS), was used to investigate the microstrip line technique performance by simulating and determine the S11 and S21 for microwave substrate materials. Results showed that the materials’ transmission, reflection, attenuation, and absorption properties could be controlled by changing the percentage of OPEFB filler in the composites. The highest absorption loss was calculated for the highest percentage of filler (70%) OPEFB at 12 GHz to be 0.763 dB, while the lowest absorption loss was calculated for the lowest percentage of filler 30% OPEFB at 12 GHz to be 0.407 dB. Finally, the simulated and measured results were in excellent agreement, but the environmental conditions slightly altered the results. From the results it is observed that the value of the dielectric constant (εr′) and loss factor (εr″) is higher for the OPEFB/PLA composites with a higher content of OPEFB filler. The dielectric constant increased from 2.746 dB to 3.486 dB, while the loss factor increased from 0.090 dB to 0.5941 dB at the highest percentage of 70% OPEFB filler. The dielectric properties obtained from the open-ended coaxial probe were required as input to FEM to calculate the S11 and S21 of the samples.

scholarly journals Frequency reconfigurable monopole antenna with DGS for ISM band applications

2018 ◽  
Vol 69 (4) ◽  
pp. 293-299 ◽  
Author(s):  
Boddapati T. P. Madhav ◽  
Shaik Rajiya ◽  
Badugu P. Nadh ◽  
Munuswami S. Kumar
Keyword(s):  
Dielectric Constant ◽  
Wireless Communication ◽  
Transmission Line ◽  
Ground Plane ◽  
Reconfigurable Antenna ◽  
Pin Diodes ◽  
Microstrip Transmission Line ◽  
Ism Band ◽  
Frequency Reconfigurable Antenna ◽  
Antenna Model

Abstract In this article a compact frequency reconfigurable antenna is presented for wireless communication applications of industrial, scientific and medical band (ISM). The proposed antenna model is designed with the dimensions of 58mm×48 mm on FR4 epoxy of dielectric constant 4.4 with the thickness of 0.8 mm. The proposed antenna consists of defected T-shape ground plane, which acts as a reflector. In the design of frequency reconfigurable antenna, BAR 64-02V PIN diodes are used as switching elements and antenna is fed by microstrip transmission line. The proposed antenna can switch at different frequencies (2.5 GHz, 2.3 GHz and 2.2 GHz) depending on the biasing voltage applied to the PIN diodes. The current antenna showing VSWR < 2 in the operating band and providing peak realized gain of 3.2 dBi. A good matching obtained between expected and the measured results.

scholarly journals Acoustic Properties of Micro-Perforated Panels Made from Oil Palm Empty Fruit Bunch Fiber Reinforced Polylactic Acid

2021 ◽  
Vol 55 (4) ◽  
pp. 343-352
Author(s):  
Vignesh Sekar ◽  
Se Yong Eh Noum ◽  
Azma Putra ◽  
Sivakumar Sivanesan ◽  
Kok Chun Chin ◽  
...  
Keyword(s):  
Polylactic Acid ◽  
Oil Palm ◽  
Acoustic Properties ◽  
Empty Fruit Bunch ◽  
Fiber Reinforced

Comparison of Dielectric Properties of Traditional and High-Oleic Runner-Type Peanuts at Microwave Frequencies

2021 ◽  
Vol 64 (6) ◽  
pp. 1817-1822
Author(s):  
Micah A. Lewis ◽  
Samir Trabelsi
Keyword(s):  
Dielectric Constant ◽  
Oleic Acid ◽  
Linoleic Acid ◽  
Dielectric Properties ◽  
Moisture Content ◽  
Loss Tangent ◽  
Loss Factor ◽  
Microwave Frequencies ◽  
High Oleic ◽  
Transmission Measurements

HighlightsPermittivity measurements were taken for traditional and high-oleic runner-type peanut pods and kernels at microwave frequencies.The dielectric constant, loss factor, loss tangent, and complex plane were compared between the two cultivars to observe any effect caused by the high-oleic trait.Despite differences in composition, minimal to no differences were observed in permittivity between the two cultivars.Abstract. Different cultivars of peanuts containing higher amounts of oleic acid have been developed to improve oxidative stability and overall peanut quality. Increasing oleic acid levels and decreasing linoleic acid levels in peanuts deter lipid oxidation, preventing the creation of off-flavors and increasing the shelf life. Since their conception, high-oleic peanuts have been tested from chemical and sensory perspectives to observe differences between them and traditional peanuts. Such tests have shown minimal differences, if any. However, tests to observe the effect of changing the levels of oleic and linoleic acid on permittivity, which is often used for nondestructive determination of the moisture content and bulk density of foods and agricultural products, have not been reported. Thus, a vector network analyzer (VNA) was used to take free-space transmission measurements of the complex permittivities of high-oleic and traditional runner-type peanut pods and kernels. Measurements were taken at 23°C between 5 and 9 GHz. Measurements yielded the dielectric constant and loss factor, which are often correlated to moisture content. Analysis was performed to compare the changes in the dielectric constant, loss factor, and loss tangent with moisture content for high-oleic and traditional peanuts. Linear trends were observed for each parameter with increasing moisture content for both cultivars. Results from the complex plane showed coefficient of determination (r2) values greater than 0.9 for pods and kernels. Therefore, at microwave frequencies, changing the levels of oleic and linoleic acid within the peanuts was observed to have minimal to no effect on their permittivity. Thus, moisture calibrations based on correlations between dielectric properties and moisture content for traditional runner-type peanuts can be applied to high-oleic cultivars. Keywords: Dielectric properties, Free-space transmission measurements, Microwave measurements, Oleic acid, Peanut kernels, Peanut pods.

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