Preliminary investigation of radar-absorbing properties of sustainable fungal biocomposites

This study explores mycelium-based biocomposites as lightweight, radar-absorbing materials for drone structures. Four variants were developed: default composite (DC), rice husk composite (RHC), silica-enhanced composite (SC), and abaca-based composite (AC), with densities ranging from 0.14 to 0.29 g/cm3. Each exhibited distinct physical and visual characteristics and was evaluated using SEM, mechanical testing, and radar cross-section (RCS) reduction. Mechanical results showed that SC achieved the highest performance, with compressive strength of 160 ± 0.1 kPa and flexural strength of 8.39 ± 2.735 MPa. DC displayed balanced properties (117 ± 14.177 kPa; 7.12 ± 0.004 MPa), while AC offered moderate strength with lower density (100 ± 20.00 kPa; 6.10 ± 0.300 MPa). RHC demonstrated the weakest performance, highlighting the influence of reinforcement type. Radar absorption, measured across 4.3–8.5 GHz, revealed that SC achieved the highest absorption of 16.88 dB at 4.97 GHz. In contrast, conventional materials such as Mylea™, Bakelite, rubber, PE, and carbon fiber showed relatively low absorption. Overall, the results establish baseline performance. However, variations in thickness, microstructure, and homogeneity affect outcomes, indicating the need for further optimization. Future work should refine composite architecture, including fiber orientation, additive loading, and density control, to enhance broadband radar absorption.