Paper-based composites as a dual-functional material for ultralight broadband radar absorbing honeycombs

The 3rd pathway of producing honeycomb-structured radar absorbing materials (HRAMs) is innovated using novel paper-based composites (PBCs) produced by a papermaking process. The PBCs consist of short-cut carbon fibers (CFs), aramid fibers (AFs), and aramid fibrils (AFBs). Thus they integrate the radar absorbing agent (CFs) into the honeycomb frames (mainly AFs and AFBs), performing as a duel-functional material for radar absorption and structural reinforcement. The PBCs containing 3 wt % of 3 mm long CFs have the maximal dielectric loss tangent and absorbance for 10 GHz microwave. The HRAMs made of PBCs consisting of 3 wt % of CFs have a low density of 28 kg/m³, and excellent microwave absorption at frequencies from 2 to 18 GHz. The HRAM with a thickness of 30 mm achieves the reflection loss < −10 dB in broad bands of 2–2.5 GHz and 4.4–18 GHz. The honeycomb model and the electromagnetic simulation method have been developed for computer-assisted design of HRAMs made of PBCs. The simulation is capable of estimating the electromagnetic behavior of HRAMs, based on the known electromagnetic parameters of corresponding PBCs. The combination of materials innovation and computer-assisted structural design will significantly accelerate the development of HRAMs.