Microwave
Mostrando 1-12 de 901 artigos, teses e dissertações.
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1. Investigate the Effect of Dielectric Properties on Microwave Absorption of Pyramidal Microwave Absorber
Abstract This paper presents an analysis of the impact of various dielectric properties material’s effects on broadband pyramidal microwave absorbers (PMA). The Computer Simulation Technology (CST) studio software simulates and analyzes the PMA over 0.7 GHz to 30 GHz frequency range. To achieve the best reflectivity performance of the PMA, different types
Journal of Microwaves, Optoelectronics and Electromagnetic Applications. Publicado em: 2022
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2. Multiphysics Design of High-Power Microwave Vacuum Window
Abstract This paper presents the Multiphysics Analysis of a High-Power Microwave Window for a Ka-Band Klystron providing 16MW of peak power. After the optimization of the electromagnetic performances, we analyze the effect of RF heating effect and the stress of the pressure on the window. We also analyze the multipactor effect, that is a common cause of wind
Journal of Microwaves, Optoelectronics and Electromagnetic Applications. Publicado em: 2022
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3. Bandpass Filter Using SIW Technology in Inductive Window Topology with Low-Cost Substrate FR-4
Abstract This paper features a step-by-step procedure for designing, simulate, and manufacture a bandpass filter using an inductive window topology within the substrate integrated waveguide (SIW) technology. We have chosen an operating frequency in the microwave range compatible with IoT circuits, employing a dielectric material, the FR-4, which is low cost
Journal of Microwaves, Optoelectronics and Electromagnetic Applications. Publicado em: 2022
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4. Valorization of Hesperidin from Citrus Residues: Evaluation of Microwave-Assisted Synthesis of Hesperidin-Mg Complex and Their Insecticidal Activity
The aim of the current study was the valorization of hesperidin, the dominant flavonoid in citrus processing waste, by microwave-assisted synthesis of hesperidin-Mg complex, improving its antioxidant activity and insecticidal potential. Here we show, for the first time, that microwave-assisted synthesis of [Mg(hesp)2(phen)]OAc (1) (hesp: hesperidin, phen: ph
Journal of the Brazilian Chemical Society. Publicado em: 2022
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5. Synthesis and characterization of α-SnWO4 powders obtained by microwave-assisted hydrothermal method
Abstract The structural, morphological, and optical properties of α-SnWO4 synthesized by microwave-assisted hydrothermal method at 150 °C for different times were investigated. XRD revealed the formation of the orthorhombic phase, without the presence of a secondary phase. The sample processed for 64 min showed a reduction in unit cell volume, suggesting a
Cerâmica. Publicado em: 2022
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6. A Design of a Compact Microwave Diplexer in Microstrip Technology Based on Bandpass Filters Using Stepped Impedance Resonator
Abstract This paper describes the design of a compact microstrip microwave diplexer based on bandpass filters and a stepped impedance resonator for 4G applications. The diplexer is composed of two band-pass filters (BPF) that operate at 1.8 and 2.5 GHz. Both bandpass filters for the receiver at 1.705-1.895 GHZ and the transmitter at 2.41-2.6 GHZ have a -3dB
Journal of Microwaves, Optoelectronics and Electromagnetic Applications. Publicado em: 2022
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7. Novel Greener Microwave-Assisted Deprotection Methodology for the 1,3-Dioxolane Ketal of Isatin Using Calix[n]arenes
In this work, the combined use of p-sulfonic acid-calix[n]arene and microwave energy to hydrolyze the 1,3-dioxolane ketal of isatin was evaluated with excellent results. This is the first time that p-sulfonic acid-calix[n]arene has been used as the catalyst in a ketal hydrolysis reaction and the deprotection of the ketone carbonyl of isatin is reported. The
Journal of the Brazilian Chemical Society. Publicado em: 2022
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8. Phase Adjustment of S-Parameters from Coupled Resonator Filters
Abstract This paper presents a method to cancel the constant phase loading and transmission line that are added to the S-parameters of coupled resonant networks. Thus, the phase-corrected S-parameters may be used to obtain a rational model together with its representative coupling matrix. This method is applicable to lossy and lossless coupled resonator netw
Journal of Microwaves, Optoelectronics and Electromagnetic Applications. Publicado em: 2022
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9. A Wideband and Wide Axial Ratio Bandwidth Circularly Polarized Antenna Loaded with Circular Ring Slot
Abstract The presented model for wideband circularly polarized microstrip antenna is an improved version of the previous models which is widely applicable to satellite, microwave relay and radar. The designed circularly polarized antenna having overall volume of 20× 20 × 1.6 mm3 actively works at the impedance bandwidth of 9000 MHz (4.0–12.9 GHz) having
Journal of Microwaves, Optoelectronics and Electromagnetic Applications. Publicado em: 2022
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10. Design and Implementation of Microwave Dual-Band Pass Interdigital Filter Using an Analytical Approach
Abstract In this paper, benefiting from frequency transformation between the normalized frequency domain of low-pass prototype frequencies and the real frequency domain of the filter, a purely analytical procedure for dual-band filter design is used. The coupling matrix of the filter is analytically extracted, without the need to perform numerical optimizati
Journal of Microwaves, Optoelectronics and Electromagnetic Applications. Publicado em: 2022
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11. Mercury Concentration in Liver Tissues of South American Fur Seals (Arctocephalus australis) from Southwestern Atlantic Ocean
Mercury (Hg) contamination of oceans is rapidly increasing, however Hg bioaccumulation in pinnipeds has been understudied. Here, we report for the first time Hg concentration in liver tissues of South American fur seals (Arctocephalus australis) in South and Southeast Brazil. Hg concentration was determined in twenty-five fur seals’ specimens found strande
Journal of the Brazilian Chemical Society. Publicado em: 2022
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12. Atomic Absorption Spectrometry as an Alternative to Determine the Presence of Gold Nanoparticles on or in Silica Matrix
Two different gold-silica-based nanomaterials were prepared: (i) silica-supported gold nanoparticles (AuNP/SiO2); and (ii) gold-silica core-shell nanoparticles (AuNP@SiO2). Three strategies for sample treatment (S), consisting in acid treatments, were employed: (S1) HNO3; (S2) HNO3 + HCl; and (S3) HF + HNO3 + HCl, applying microwave oven digestion for S2 and
Journal of the Brazilian Chemical Society. Publicado em: 2022