Double-Sided Metasurface Array for a Dual-Band and Polarization-Independent Microwave-Energy-Harvesting System

Miniaturized Broadband Bi-Yagi Antenna Array for Ambient RF Energy Harvesting

This paper presents a miniaturized broadband Bi-Yagi antenna array that covers a bandwidth from 1.79 GHz to 2.56 GHz. The proposed antenna achieves a tradeoff between maximizing bandwidth, effective area, and gain while minimizing physical dimensions. The antenna design considers the coupling between the radiator and director elements, resulting in increased bandwidth as the resonating modes shift apart. Additionally, the proposed design optimizes element spacing and dimensions to achieve high gain, wide bandwidth, efficient radiation, and a minimum aperture size. The proposed antenna, with physical dimensions of 138.6 mm × 47.7 mm × 1.57 mm, demonstrates gains ranging from 6.2 dBi to 9.34 dBi across the frequency range, with a total efficiency between 88% and 98%. The proposed design is experimentally validated by measuring the reflection coefficients, input impedance, gain, and normalized radiation pattern. These features make the antenna well suited for capturing and harvesting electromagnetic waves in mobile wireless and Wi-Fi applications.

Dual-Band, Wide-Angle, and High-Capture Efficiency Metasurface for Electromagnetic Energy Harvesting

A dual-band metasurface (MS) with a wide reception angle operating at Wi-Fi bands (2.4 GHz and 5.4 GHz) is presented for electromagnetic (EM) energy harvesting applications. The MS unit cell comprises a subwavelength circular split ring resonator printed on the low-loss substrate. An air layer is sandwiched between two low-loss substrates to enhance the harvesting efficiency at operating frequencies. One of the main advantages of the proposed MS is that it uses only one harvesting port (via) to channel the captured power to the optimized load (50 Ω), which simplifies the design of a combined power network. According to the results of full-wave EM simulations, the proposed MS has a near-unity efficiency of 97% and 94% at 2.4 GHz and 5.4 GHz, respectively, for capturing the power of incident EM waves with normal incidence. Furthermore, the proposed MS harvester achieves good performance at up to 60° oblique incidence. To validate simulations, the MS harvester with 5 × 5-unit cells is fabricated and tested, and its EM properties are measured, showing good agreement with the simulation results. Because of its high efficiency, the proposed MS harvester is suitable for use in various microwave applications, such as energy harvesting and wireless power transfer.