Metamaterial-based microwave absorbers: a critical review of design principles and emerging applications

The remarkable abilities of metamaterial-based microwave absorbers (MMA) to regulate electromagnetic (EM) waves have attracted a lot of interest since they facilitate effective energy absorption at a variety of frequency ranges. The design ideas, material choices, and structural advancements that support MMA performance are the main topics of this comprehensive review. The mechanisms of absorption, such as resonance, reduction of plasma frequency, and impedance matching, have been highlighted, along with the function of material and geometric tunability in attaining wideband, angle-independent, and polarization-insensitive absorption. A special emphasis is provided to the classification of MMA based on the material composition, including dielectric, metal, magnetic, carbon, polymer, plasma, and hybrid along with their impacts on the performance characteristics. The emerging utilization of MMA is being investigated in areas such as wireless communication, electromagnetic interference (EMI) shielding, stealth technologies, antennae, and sensing. Recent developments in fabrication of MMA that use flexible, reconfigurable, and multipurpose materials to increase their potential in dynamic contexts are also highlighted in this review. Future directions for performance optimization and application scope expansion are examined, along with challenges about scalability, manufacturing accuracy, and integration with current technology.