Compact wide-angle polarization-insensitive triple-band metamaterial absorber for efficient microwave energy harvesting with RF-to-DC conversion

Abstract This article presents a compact, triple-band, polarization-independent metamaterial absorber (MMA) designed for efficient RF energy harvesting. The MMA achieves over 99% absorption at 6.48 GHz (C-band), 17.74 GHz (Ku-band), and 27.1 GHz (Ka-band), maintaining stable performance under transverse electric, transverse magnetic, and TEM polarizations. Optimally positioned lumped resistive loads enhance energy capture and enable scalability for array configurations. An equivalent circuit model developed in Advanced Design System aligns well with full-wave CST simulations, confirming design accuracy through S 11 parameter validation. The MMA achieves RF to alternating current (AC) conversion efficiencies of 97.61%, 91.67%, and 90.82% at the respective resonant frequencies. Single-series and voltage doubler rectifiers convert the captured AC energy to direct current, reaching rectification efficiencies of 71.2%, 59.25%, and 51.34%, with power conversion efficiencies of 69.49%, 54.31%, and 46.62%. Parametric studies assess input power and load resistance impacts, optimizing performance. Combining compactness, multi-band operation, and high conversion efficiency, this MMA advances microwave energy harvesting for scalable applications.