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 ε′ and dielectric losses tanδ) 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.

在这项工作中，研究了一种新的复合材料，特别是用于消声室的微波吸收应用。我们建议用填充有碳纤维的环氧树脂泡沫代替目前用于商业吸收器的炭黑负载聚氨酯泡沫。本文的目的是研究三种分散方法（刮刀，剪切混合器和超声探头）和四种纤维长度（1 mm，3 mm，6 mm和12 mm）对均匀性和介电性能（介电常数ε）的影响'和介电损耗黄褐色δ）的复合材料。用刮铲分散的长纤维已显示出比短纤维更高的介电性能。但是，发现这种软分散方法不能有效地分散长纤维。尽管用剪切混合器获得了均匀的分散体（机械分散体），但我们注意到纤维的重要降解，导致介电性能下降。超声分散似乎是复合材料均匀性和介电性能之间的良好折衷。最终，电磁仿真预测了由8 mm至18 GHz频率范围内负载12 mm碳纤维的复合材料制成的金字塔形吸收体的高吸收性能，其反射损耗低于− 50 dB。