Thin-thickness 3D-printed dielectric loss multi-layer nested ultra broadband radar absorbing metastructure with wide incident angle

Efficient radar cross section (RCS) reduction under broadband and wide-angle incidence constraints is a core bottleneck for modern equipment stealth, yet existing absorbers face issues like excessive thickness, narrow bandwidth, and poor wide-angle performance. This study proposes an innovative multi-layer nested three-dimensional radar wave absorbing metastructure and introduces a cell random deflection parameter to expand the design methodology for absorbing metastructure. Based on a finite cellular electromagnetic model and the non-dominated sorting genetic algorithm II (NSGA-II), a multi-objective optimization framework for wide-angle incident three-dimensional (3D) absorbing metastructure is developed. A high-dielectric-loss composite absorber filament were fabricated using polylactic acid/carbon black hybrid particles as raw material. An optimized, thin-thickness (9.6 mm) multi-layer nested square frame ultra-broadband radar wave absorber is produced via fused deposition modeling 3D printing, achieving a vertical reflection loss (RL) of less than −10 dB over the 2–40 GHz bandwidth. The random-deflection design significantly enhanced the multi-layer nested square frame's wide-angle absorption performance: average RL remained < −19.3, −18.5, −18.0, and −11.5 dB at 15°, 30°, 45°, and 60° incidence, respectively. Field and power loss contour analyses revealed the multi-scale ultra-broadband absorption mechanism of the multi-layer nested square frame metastructure absorber. This work advances thin wide-angle stealth structure design/manufacturing, supporting next-generation omnidirectional stealth technology and expanding 3D printing applications in electromagnetic devices.