Wide-angle stable polarization-independent dual-band metamaterial absorber for 5G n77/n79 energy harvesting applications

In this study, a compact dual-band square-ring resonator (SRR) based metamaterial absorber (MMA) operating in the 5G NR n77 (3.3–4.2 GHz) and n79 (4.4–5.0 GHz) frequency bands is proposed for microwave energy harvesting applications. The proposed MMA consists of two nested square-ring resonators rotated by 45° with respect to the x-axis, four auxiliary square rings placed at the corners of the inner resonator, an FR-4 substrate, and a continuous copper ground plane. Numerical simulations demonstrate absorption levels of 99.8% at resonance frequencies of 3.63 GHz and 4.67 GHz. The absorption mechanism is investigated through surface current distributions, electromagnetic field analysis, and effective medium parameter retrieval. Furthermore, this study introduces a physics-driven optimization strategy based on controlled doublet resonance, which enhances angular stability at oblique incidence angles without increasing structural complexity. The proposed design simultaneously achieves near-perfect absorption (99.8%), complete polarization independence (0°–90°), and superior angular stability up to 70° for both TE and TM modes on a low-cost FR-4 substrate. These features, along with a compact footprint (EMR of 4.12), offer an economically viable and high-performance electromagnetic surface specifically optimized for large-scale 5G n77/n79 energy harvesting applications.