Polarization-insensitive, negative indexed inverted U-shaped flexible metamaterial absorber based on microstructure resonator for multi-band energy harvesting

This article presents a polarization-insensitive, negative indexed inverted U-shaped flexible metamaterial absorber based on a microstructure resonator for multi-band energy harvester application. The vertical inverted U-shaped joint and central split ring resonator together create significant resonance covering three consecutive L-, S-, and C-band absorption peaks for four resonance frequencies: 1.975 GHz with 99.99% absorption, 2.85 GHz with 99.28% absorption, 5.265 GHz with 96.79% absorption, and 5.5 GHz with 89.12% absorption. The design has a rare double negative metamaterial feature at 5.265 GHz, while a balanced geometrical appearance that is polarization insensitive for θ and φ improved the structure’s durability and tunability. Finite computer simulation technology was used to simulate and examine the mechanisms involved in absorption at 1— 6 GHz. Based on Rogers RO4350 B and copper, the structural design showed excellent absorption for 15° and 30° bends and 2 × 4, 4 × 8 arrays with an efficiency of 96.38% at an incidence angle of 30° in transverse magnetic mode, a 3x 3 array was developed for energy harvesting. For energy harvesting applications using array structure, the efficiency parameter is unnoted in most of the reported articles. Moreover, the array demonstrated polarization insensitivity for both transverse electric and transverse magnetic modes at angles of 0°, 30°, and 60°. The proposed quad-band absorber shows significant potential for energy harvesting applications.