Microwave absorber surface design for 5G energy harvesting applications

This study presents a high-efficiency microwave absorber for energy harvesting in 5G frequencies. Initially, a unit cell was designed in four stages to efficiently absorb in the targeted frequency region. The results obtained for each stage of the design were analyzed, and additional investigations were conducted for substrate material and thickness based on the optimum performance of the unit cell structure. A unit cell absorber designed on an FR4 a flame-resistant fiberglass/epoxy-based composite, commonly utilized in printed circuit boards due to its favorable electrical insulation properties and low cost. With a thickness of 1.5 mm, the absorber achieved a 98.04% absorption at 3.8 GHz according to simulation results. Subsequently, this unit cell was separately designed and simulated with different periodic arrays to transform into an absorber surface. As a result, high absorption rates of 98.94% and 98.35% were achieved at 3.8 GHz and 4.2 GHz, respectively, in the 2 x 2 array. It was observed that the structure absorbs over 85% within a 1 GHz bandwidth between 3.5 GHz and 4.5 GHz. Finally, a prototype of the absorber surface was manufactured, and measurements were taken in the laboratory environment. Significant agreement was found between the data obtained from these measurements and the simulation results. The results indicate that the suggested absorber surface is well-suited for energy harvesting within the n77 (3.3 GHz to 4.2 GHz) and n78 (3.3 GHz to 3.8 GHz) bands of 5G communication.