Electromagnetic Absorption Mechanism of TPMS-Based Metastructures: Synergy Between Materials and Structures

3D metastructure absorbers have gained attention for their lightweight, load-bearing capabilities, and superior electromagnetic wave absorption. However, the complex interplay between unit cell geometry, material properties, and electromagnetic response is not well understood, hindering the design of high-performance devices. A multi-scale model, validated is presented by simulations and experiments, that clarify the relationship between materials, structures, and electromagnetic behavior in 3D metastructures. By systematically investigating strut-based and sheet-based structures, volume fraction, unit size, crystal lattice orientation, and density gradient within TPMS-based unit cells, it is revealed that unit geometry significantly influences electromagnetic field propagation and reflection loss. Specifically, under the same unit size, sheet-based TPMS metastructures exhibit stronger reflectivity than strut-based ones, while multilayer structures show the opposite trend. The direct correlation is also further confirmed between geometric symmetry and polarization insensitivity, with orthogonal isotropic superstructures displaying excellent polarization-insensitive properties. This finding provides a new design principle for achieving robust, angle-independent absorption in these materials. This work enhances understanding of the structure-electromagnetic behavior interplay, guiding the design of next-generation broadband, wide-angle, and polarization-insensitive devices.