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Microwave absorbing materials based on epoxy foam loaded with long carbon fibers

Abstract : This work focuses on the design, elaboration, and measurement of microwave absorbers. Several types of absorbers have been studied in the frequency range from 0.75 GHz to 18 GHz. First, planar multilayer absorbers have been made epoxy foams loaded with different weight percentages (between 0.0125 and 10%) of carbon fibers with lengths between 100 µm and 12 mm. The absorption performance of these multilayers has been optimized while reducing their compactness, thanks to a MATLAB code and the use of a genetic algorithm. The composition and thickness of each layer could thus be optimized and led to the production of several high-performance prototypes (absorption> 90%) of low thicknesses (between 50 mm and 98 mm), very lightly loads (<0.075% fiber), and with very low density (0.06 g.cm-3). Second, metamaterial (MM) absorbers have been studied. A new multi-resonant geometry (called Vshape), presenting several absorption peaks on the studied frequency band, has been proposed; an analytical calculation of the reflection coefficient, using the extracted effective properties, was implemented. The simulation, measurement as well as analytical calculation of this MM show very consistent results thus validating our models. Finally, a hybrid absorber, combining a thin layer of epoxy foam loaded with carbon fibers to the metamaterial, was proposed to broaden its bandwidth. Thus, a planar ultra-wide-band absorber (with a reflection coefficient <-10 dB between 2.6-18 GHz) could thus be obtained. This absorber shows the best compromise between thickness/absorption band/absorption frequency presented to date in the literature.
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https://tel.archives-ouvertes.fr/tel-03337128
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Submitted on : Tuesday, September 7, 2021 - 4:05:10 PM
Last modification on : Tuesday, May 10, 2022 - 2:48:39 PM
Long-term archiving on: : Wednesday, December 8, 2021 - 8:00:07 PM

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  • HAL Id : tel-03337128, version 1

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Aicha El Assal. Microwave absorbing materials based on epoxy foam loaded with long carbon fibers. Networking and Internet Architecture [cs.NI]. Université Rennes 1; Université Libanaise, 2021. English. ⟨NNT : 2021REN1S013⟩. ⟨tel-03337128⟩

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