A coated 3D-printed polymer metamaterial with ultra-broadband effective absorption using a MWCNT-carbonyl iron powder composite

In this study, we developed a coated Fused Deposition Modeling (FDM) three-dimensional (3D)-printed polymer metamaterial with ultra-broadband effective absorption using a composite coating of multi-walled carbon nanotubes (MWCNT) and carbonyl iron powder (CIP). The integration of MWCNT with CIP was employed to synergistically optimize the electromagnetic parameters. The optimal component ratio was identified and applied as a coating layer on a 3D-printed truncated cone pyramid structure. CST Microwave Studio simulation software was used to optimize the structure and analyze the effects of the electromagnetic parameters, dimensions, polarization angle, and incidence angle on absorption performance. The optimized periodic structure exhibited a peak reflection loss of −49.56 dB and an effective absorption bandwidth of 14.37 GHz (3.63–18 GHz), with an average effective absorption rate of 89.8% across the 2–18 GHz range. The absorber demonstrated polarization insensitivity and wide-angle absorption capability. An optimized coated truncated cone metamaterial was successfully fabricated using FDM 3D printing, and the experimental results were in good agreement with the simulations. The absorber accounted for only 9.3 wt% of the total mass, highlighting the advantages of this approach in achieving broadband absorption along with lightweight and low-cost characteristics through the integration of 3D printing and coating techniques.