Dual-Band Rectifying Metasurface for Energy Harvesting With Second-Order Response

Conventional multi-frequency rectifying metasurface (RMS) generally suffer from drastically degraded rectification efficiency at slight frequency shifts. To this end, this letter presents a dual-band second-order RMS based on a multi-mode patch resonator. Through etching symmetrical ring slots and bended H-shaped slots into the unit, four resonating modes are effectively excited and properly allocated to cover dual ISM bands. A 6×6 array prototype was fabricated and experimentally evaluated. The measured total efficiency remains above 50% in the 2.51–2.595 GHz band and above 35% in the 5.68–5.8 GHz band, with peak values reaching 53% and 42.2%, respectively. Moreover, the proposed RMS maintains stable performance under varying polarization conditions. As the main advantages, the second-order response is firstly designed for broader bandwidth and improved frequency selectivity. As a result, the proposed RMS shows strong potential for application in energy harvesting systems, where it can significantly improve the frequency robustness of the rectification efficiency.