%0 Journal Article %T Carbon Fibers Loaded Composites for Microwave Absorbing Application: Effect of Fiber Length and Dispersion Process on Dielectric Properties %+ Institut d'Électronique et des Technologies du numéRique (IETR) %A Benzerga, R. %A Badard, M. %A Mejean, C. %A El Assal, A. %A Le Paven, C. %A Sharaiha, A. %Z European Union through the European Regional Development Fund (ERDF)European Union (EU) %Z Ministry of Higher Education and ResearchMinistry of Higher Education and Scientific Research (MHESR) %Z Region BretagneRegion Bretagne %Z Departement des Cotes d'ArmorRegion Bretagne %Z Saint-Brieuc Armor Agglomeration, through the CPER Project 2015-2020 MATECOM %Z Saint-Brieuc Armor Agglomeration, through the CPER Project 2015-2020 SOPHIE/STIC Ondes %< avec comité de lecture %@ 0361-5235 %J Journal of Electronic Materials %I Institute of Electrical and Electronics Engineers %V 49 %N 5 %P 2999-3008 %8 2020-05 %D 2020 %R 10.1007/s11664-020-07998-y %K Absorber composites %K dielectric properties %K fiber dispersion %K carbon fibers %Z Life Sciences [q-bio]Journal articles %X In this work, a new composite for microwave absorption applications, especially for anechoic chambers, is studied. We propose to substitute carbon black loaded polyurethane foam, currently used in commercial absorbers, by epoxy foam filled with carbon fibers. The purpose of the present paper is to study the influence of three dispersion methods (spatula, shear mixer and ultrasound probe) and four fiber lengths (1 mm, 3 mm, 6 mm and 12 mm) on the homogeneity and dielectric properties (permittivity epsilon ' and dielectric losses tan delta) of achieved composites. Long fibers dispersed with spatula have shown higher dielectric properties than short fibers. However, such a soft dispersion method was revealed to be inefficient to disperse properly the long fibers. Although a homogenous dispersion was obtained with the shear mixer (mechanical dispersion), we noticed an important degradation of the fibers which lead to a decrease of the dielectric properties. Dispersion with ultrasounds appears to be a good compromise between homogeneity and dielectric properties of composites. Finally, electromagnetic simulation predicted a high absorption performance for pyramidal absorber made with the 12 mm-carbon fibers loaded composite with reflection loss lower than - 50 dB for frequencies ranging between 8 GHz and 18 GHz. %G English %L hal-02530972 %U https://univ-rennes.hal.science/hal-02530972 %~ UNIV-NANTES %~ UNIV-RENNES1 %~ CNRS %~ INSA-RENNES %~ IETR %~ IETR_MF %~ STATS-UR1 %~ CENTRALESUPELEC %~ UR1-HAL %~ UR1-MATH-STIC %~ UR1-UFR-ISTIC %~ IETR-CUTE %~ IETR-FUNMAT %~ IETR-ADH %~ TEST-UR-CSS %~ UNIV-RENNES %~ INSA-GROUPE %~ TEST-HALCNRS %~ UR1-MATH-NUM %~ IETR-STAR %~ NANTES-UNIVERSITE %~ UNIV-NANTES-AV2022 %~ TEST3-HALCNRS