Unraveling the Orientation‐Property Relationship in Graphene Fibers for Enhanced Microwave Absorption

Abstract Graphene fibers hold great promise for next‐generation microwave absorption (MA) applications, but their performance is often hindered by poor impedance matching and inefficient electromagnetic wave attenuation. In this study, it is demonstrated that graphene orientation is a critical structural parameter for optimizing MA performance. By utilizing expansion‐extension flows during coaxial wet spinning, precise tuning of graphene orientation from axial to radial alignment is achieved. A real‐time polarized optical characterization platform enables operando monitoring of orientation evolution, revealing a predictable relationship between flow parameters and graphene alignment. Experimental measurements and electromagnetic simulations show that the orientation of graphene fibers governs internal electric field distribution and impedance matching, resulting in a tunable MA response. Optimized fibers exhibit an effective absorption bandwidth of 6.28 GHz and a minimum reflection loss of −66.7 dB. These findings position orientation engineering as a powerful strategy for enhancing MA materials and provide a generalizable framework for structure‐property optimization in macroscopic nanocarbon assemblies.