Complex Permittivity
Mostrando 1-12 de 28 artigos, teses e dissertações.
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1. Frequency Selective Surface Properties of Microwave New Absorbing Porous Carbon Materials Embedded in Epoxy Resin
In this manuscript, the electromagnetic wave absorption properties of sustainable porous carbon composites were evaluated over the X-band frequency range (8.2 - 12.4 GHz). The porous carbon material was made from the byproduct of cellulose production and was used as additive on the development of radar absorbing material (RAM) composites. These porous carbon
Mat. Res.. Publicado em: 21/10/2019
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2. The Modification of (Nd0.5Ta0.5)4+ Complex-Ions on Structure and Electrical Properties of Bi0.5Na0.5TiO3-BaTiO3 Ceramics
The (Bi0.5Na0.5)0.94Ba0.06Ti1-x (Nd0.5Ta0.5) xO3 (0.01≤x≤0.05) lead-free ceramics (BNBT-xNT) used (Nd0.5Ta0.5)4+ complex-ions to modify its structure and electrical properties. The BNBT-xNT ceramics exhibit the coexistence of tetragonal and rhombohedral phase. The (Nd0.5Ta0.5)4+ complex-ions prohibit grain growth, and its average grain size decreases fro
Mat. Res.. Publicado em: 14/03/2019
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3. Effect of PANI on Thermal, Mechanical and Electromagnetic Properties of HDPE/LLDPE/PANI Composites
In this work, polyaniline (PANI) in emeraldine-base form, synthesized by chemical oxidation polymerization, was protonated with hydrochloric acid (HCl). Composites based on high-density polyethylene (HDPE) and linear-low density polyethylene (LLDPE) blends with PANI were prepared in molten condition using a torque rheometer. The effect of compatibilizer agen
Mat. Res.. Publicado em: 11/12/2017
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4. Design of coaxial aircell fixture for the measurement of electromagnetic properties
Abstract Coaxial aircells are designed and fabricated to measure the electromagnetic properties of ferrite materials in the frequency range from 1 MHz to 3.6 GHz. These S-parameters are actually measured connecting the aircell to a vector network analyzer (VNA). The electromagnetic properties such as complex permittivity and complex permeability are extracte
J. Microw. Optoelectron. Electromagn. Appl.. Publicado em: 2017-09
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5. Copper Cobalt Magnetic Ceramic Materials Characterization at Terahertz Frequencies
ABSTRACT: This study presents the complex index of refraction and the complex permittivity of a magnetic ceramic material made of copper, cobalt, and iron oxides. The index of refraction and the extinction coefficient of the CuCo-ferrite exhibit an almost frequency independent behavior and were averaged to n = 3.62 ± 0.05 and k = 0.06 ± 0.02, respectively,
J. Aerosp. Technol. Manag.. Publicado em: 2017-06
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6. Synthesis, Characterization and Dielectric Properties of New 5-(4-Hydroxyphenyl)- 10,15,20-tri-4-[2-(3-pentadecylphenoxy)ethoxy]phenyl porphyrin and Their Ni, Co and Cu Complexes
New asymmetric cardanol-based porphyrins, free-base and coordinated with Ni, Co and Cu, were synthesized and completely characterized as A3B type. Such porphyrins were obtained aiming improved solubility in polar solvents due insertion of an -OH phenolic group. Their thermal and dielectric properties were also evaluated. Changes in the synthetic route reduce
J. Braz. Chem. Soc.. Publicado em: 2017-06
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7. Electromagnetic Characterization of Aircraft Composite Materials and its Effects on the Antenna Performance
Abstract This paper presents an electromagnetic characterization of aircraft composite materials, as well as numerical and experimental analyses of its effects on the antenna performance. Two uncalibrated S-parameters characterization methods have been applied for retrieving the complex electrical permittivity in the L- and C-band, namely: Air-region method
J. Microw. Optoelectron. Electromagn. Appl.. Publicado em: 2017-03
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8. Electrical Conductivity in the KDP, ADP, and K1-x(NH4)xH2PO4 Crystals
Impedance Spectroscopy was performed to examine the electrical conductivity on KH2PO4 KDP, (NH4)H2PO4 ADP and K1-x(NH4)xH2PO4 (x = 0.076, 0.118, 0.357, 0.857, 0.942) crystals with increasing temperature. They were grown by solvent evaporation method. Zview simulation software was used to theoretically fit electrical conductivity results as a function of freq
Mat. Res.. Publicado em: 23/02/2017
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9. Effect of oxidants and anionic surfactants on the morphology and permittivity of polypyrrole and its blends with epoxy resin
Abstract In this work, conductive polymers were prepared based on polypyrrole (PPy) and its blends with epoxy resin. The chemical syntheses of PPy used two oxidants (Fe2(SO4)3 and FeCl3.6H2O) and two surfactants (DBSNa and DBSA). PPy samples and their blends were characterized by scanning electron microscopy, electrical conductivity by four points, and measu
Polímeros. Publicado em: 18/08/2016
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10. Measured Dielectric Permittivity of Contaminated Sandy Soil at Microwave Frequency
Abstract Measurement of dielectric permittivity of soil has been studied by many researchers. However, few studies have been conducted on contaminated soil. The motivation of the present study is to investigate the behavior of sandy soil contaminated by lubricant oil at microwave frequency. Two different artificially prepared soil samples are measured in the
J. Microw. Optoelectron. Electromagn. Appl.. Publicado em: 2016-06
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11. Anionic Aliphatic Polyesteramide Copolymers: Evaluation of Dielectric Properties
This study looks at the effects on the dielectric behavior as result of the incorporation of ester sequences along the nylon 6 chains. The aliphatic polyesteramide copolymers and nylon 6 homopolymer were synthesized via anionic ring-opening copolymerization using the rotational molding technique by varying the ratio of the ε-caprolactam (CLA) and ε-caprola
J. Braz. Chem. Soc.. Publicado em: 2015-02
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12. Complex permeability and permittivity variation of radar absorbing materials based on MnZn ferrite in microwave frequencies
The complex dielectric permittivity (ε) and magnetic permeability (µ) of Radar Absorbing Materials (RAM) based on magnetic particles (MnZn ferrite particles) embedded in a dielectric matrix (silicon rubber) have been studied in the frequency range of 2 to 18 GHz. The relative permeability and permittivity of MnZn ferrite-silicon composites for various mass
Mat. Res.. Publicado em: 21/05/2013