Geometric Design Effects on the Electromagnetic Absorption of <scp>3D</scp> ‐Printed Multilayer Polymeric Structures for Radar Stealth Applications

ABSTRACT The development of lightweight radar‐absorbing structures (RAS) based on additively manufactured polymers offers an alternative route for geometry‐driven electromagnetic attenuation. In this study, the influence of structural architecture and layer sequencing on the electromagnetic absorption performance of 3D‐printed polylactic acid (PLA)‐based structures was systematically investigated. Three configuration categories were analyzed: (i) porous architectures (honeycomb, re‐entrant, and auxetic), (ii) surface geometries (rectangular, triangular, sinusoidal, and circular), and (iii) multilayer systems integrating the most effective porous and geometric profiles. Samples were fabricated via fused deposition modeling (FDM) and their performance was evaluated in the X‐band frequency range (8.2–12.4 GHz). Among the single‐layer designs, the honeycomb exhibited reflection loss (RL) of approximately −18 dB, while the triangular surface profile provided broadband absorption with RL of approximately −20 dB. When these geometries were combined in multilayer architectures (total thickness of 8 mm), enhanced absorption performance was observed, with the honeycomb–triangular system attaining RL of approximately −25 dB, depending on orientation. Additional investigation of hybrid multilayers incorporating conductive PLA (cPLA) demonstrated that insertion of a single conductive intermediate layer (PLA/cPLA/PLA) improved attenuation compared to fully dielectric or fully conductive stacks, indicating a balance between conduction‐related losses and impedance matching. The results demonstrate that electromagnetic absorption in polymer‐based RAS can be modulated through geometric optimization and controlled conductivity, providing an approach for design of lightweight, mechanically robust, and customizable stealth materials.