Optimization of the microwave absorptivity of SiCf/Resin composites in the GHz range

Abstract The effects of structural factors on the electromagnetic wave absorption properties of SiC fibre reinforced resin composites (SiCf/Resin) were investigated. Transmission line theory was used to calculate the reflection loss and to tap the potential of SiC fibres as broadband wave absorbents. The structure of the SiCf/Resin composite was optimized based on a double-layered laminate containing high-resistance SiC fibres (H-SiCf, ρ = 6.5 × 105 Ω cm) in the upper layer and low-resistance SiC fibres (L-SiCf, ρ = 109.7 Ω cm) in the bottom layer. The calculation suggests that to achieve a high absorptivity better than −10 dB, the permittivity of the L-SiCf/Resin bottom layer must be enhanced to quite a high value with a specific frequency dispersion degree. The desired permittivity was realized by controllable addition of carbon black into L-SiCf/Resin. Under the optimized thickness combination, the reflection loss of the double-layered composite could be lower than −13.3 dB in the whole X and Ku bands.