Wrapping of Curved Surfaces With Conformal Broadband Metamaterial Microwave Absorber

In this letter, three different wrapping methods i.e., circle having incisions (CI), pentagon and hexagon (P&H) and petals wrapping are proposed for covering of spherical shaped surfaces with flat microwave metamaterial absorber (MMA) without defects. To achieve the better performance, an extensive analytical study was carried for counting the number of unit cells and packing fraction in the aforementioned techniques. It was found that maximum number of unit cell can be wrapped over a spherical ball by using CI method. The maximum packing fraction was found to be in P&H method. Further, we studied variation in the number of unit cells and packing fraction for variation in the shapes (circle, square, and hexagon) and size (2-4 mm) of the unit cell. For experimental purpose, an indium tin oxide coated over polyethylene terephtalate (ITO/PET)-based conformal MMA was designed and then fabricated using excimer laser micromachining. The proposed conformal absorber gives broadband absorption from 6.21 to 15 GHz. Finally, the fabricated absorber was wrapped on a spherical ball and microwave response was measured. The measured microwave response was compared with the simulated response and found to be in good agreement with each other.