Hierarchical chiral core–shell FM/CNF@P–CoFe composite fibers for broadband microwave absorption via guide–capture–dissipate

Abstract

Abstract

Balancing impedance matching with sufficient electromagnetic attenuation remains a central challenge in the development of broadband microwave absorbers. Here, hierarchical chiral core–shell FM/CNF@P–CoFe composite fibers were constructed by textile twisting of a ferromagnetic microwire (FM) and a carbon nanotube fiber (CNF) into a heterogeneous double-helical core, followed by deposition of a porous nanofibrous shell containing Co/CoFe 2 O 4 . Systematic variation of the Co/CoFe 2 O 4 loading revealed a loading-dependent balance between impedance matching and internal attenuation. Although FM/CNF@P–CoFe–18 retains a relatively high attenuation constant over part of the investigated frequency range, FM/CNF@P–CoFe–12 provides the most favorable balance between impedance matching and internal attenuation. Based on the effective electromagnetic parameters measured for the aligned assemblies, FM/CNF@P–CoFe–12 yields a calculated minimum reflection loss ( RL min ) of − 42 dB and an effective absorption bandwidth ( EAB ) of 9.6 GHz at a matching thickness of 1.75 mm. Comparative full-wave simulations further indicate topology-dependent redistribution of the internal electromagnetic field associated with the heterogeneous double-helical core. These results support a “Guide–Capture–Dissipate” (GCD) framework describing the roles of impedance regulation, field redistribution, and electromagnetic dissipation. Homogenized equivalent-layer simulations further predict a radar cross-section (RCS) reduction of at least 14.6 dB m 2 at 12 GHz over incidence angles up to 60°. Overall, broadband absorption in this hierarchical composite fiber system arises from a favorable balance between impedance matching and internal attenuation, with the double-helical topology mediating internal electromagnetic-field redistribution.