Truly All-Dielectric Ultrabroadband Metamaterial Absorber: Water-Based and Ground-Free

A truly all-dielectric metamaterial absorber, made of subwavelength water-based resonators and free of metallic ground, is designed, fabricated, and characterized. We demonstrate theoretically and experimentally that our metamaterial features a highly uniform perfect absorption for frequencies between 7.74 and 23.56 GHz, perfect thermal stability for temperatures from 0 to 100 °C, and excellent absorption performance for large angles of oblique incidence. The proposed metamaterial absorber can be fabricated at low cost, is environment friendly, and may find potential applications in broadband scattering reduction and electromagnetic energy harvesting.