▎ 摘　　要

A novel gradient graphene composite composed of three-layers was fabricated by fused deposition modelling (FDM) with graphene oxide (RGO)/polylactic acid (PLA) as the printing filaments. Based on the analysis of the electromagnetic parameters of samples with different graphene contents, the thickness range of each functional layer was determined by the reflection loss model. The results show that when 5 wt%, 7 wt% and 8 wt% of graphene contents were selected as the three functional layers, the gradient structure absorber has better electromagnetic absorption effect than the homogeneous absorber. The sample achieving -8 dB broadband absorption in the X and Ku bands and a maximum absorption peak of -30 dB at 17 GHz for a 4 mm-thick composite absorber. The excellent microwave absorption ability could be attributed to the gradient distribution of graphene composites, which proper impedance matching, the substantial dielectric loss in graphene, the interfacial void, interfacial polarization loss.