Design of melamine/ZIF-67-derivatives based Z-shaped metamaterial for ultra-broadband microwave absorption

Confronted with the increasing requirements for electromagnetic (EM) wave absorbers utilized in a complex environment, there has been extensive research on designing components and structures for enhancing the EM response ability. Combining artificially engineered structures with electromagnetic (EM) wave absorption materials is an effective approach for significantly expanding the effective absorption bandwidth; therefore, in this work, Z-shaped 3D metamaterials filled with melamine/ZIF-67 derivatives were obtained by integrating the simulation design, experimental replication, and mechanism verification. MZ-600-based Z-shaped 3D metamaterial absorbers exhibited outstanding performances (an RL_min of -20.75 dB with an EAB of 12 GHz at 6.5 mm) due to the synergistic loss ranging from microscopic material loss to macroscopic structural consumption of the incident EM wave. In detail, magnetic/dielectric melamine/ZIF-67 derivatives were responsible for absorbing the EM energy via the intrinsic loss of fillers, while the designed metamaterials contributed to the broadened bandwidth via optimizing the impedance match and manipulating the EM field. In addition, an ultra-wide angular adaptability of ±70° (15°-85°), polarization insensitivity (TE and TM) and a large decrease in RCS values (42.86 dB m²) demonstrated the potential of the as-prepared metamaterial in practical applications. The results suggested that integrating microscopic fillers with artificially engineered structures is an attractive avenue to enable high-efficiency EM wave absorption performance.