Biomimetic concave basalt fiber-reinforced composite integrating <?A3B2 pi6?>ultra-broadband absorption and excellent mechanical properties <?A3B2 pi6?>inspired by wing scales of butterfly

The radar stealth performance of weaponry is crucial to their battlefield survivability, jointly determined by the effective absorption bandwidth (EAB) and mechanical properties of microwave-absorbing materials (MAMs). However, conventional MAMs often suffer from narrow EAB and absorption coatings prone to detachment. Herein, inspired by the wing scales of butterfly, we develop a biomimetic concave basalt fiber-reinforced composite (BC-BFRC) that delivers both broadband absorption and superior mechanical performance. Remarkably, the BC-BFRC achieves an EAB (reflection loss −10 dB) of 14.7 GHz (3.3–18 GHz), which is 26.7% higher than the conventional planar structure (planar BFRC) and covers 91.9% of the S–Ku band. It maintains stable broadband absorption across incidence angles of 0°–45° (reflection loss −8 dB at 4–18 GHz) and is insensitive to the incident direction. In fact, the broadband absorption originates primarily from impedance gradient between the layers and energy capture induced by the biomimetic concave at bottom. Critically, the composite exhibits a flexural strength of 239.2 MPa, enabled by basalt fiber reinforcement. This work provides a novel biomimetic strategy and feasible pathway for realizing structure-function integration of MAMs, enabling advanced radar stealth and electromagnetic shielding applications.