Metamaterials, a kind of artificially structured materials, have attracted extensive attention in the last decade, owing to their exotic properties that are not readily available in nature. With the development of metamaterials, a series of intriguing applications have been emerged, such as artificial optical chirality, wavefront modification, and cloak of invisibility. It is known that one of the main obstacles towards their engineering applications is the inevitable intrinsic loss in metamaterials.
A subwavelength water metamaterial is proposed and analyzed for ultra-broadband perfect absorption at microwave frequencies. We experiment this metamaterial shows over 90% absorption within almost the entire frequency band of 12–29.6 GHz. It is also shown that the proposed metamaterial exhibits a good thermal stability with its absorption performance almost unchanged for the temperature range from 0 to 100◦C. The study of the angular tolerance of the metamaterial absorber shows its ability of working at wide angles of incidence. The proposed water metamaterial absorber is low-cost and easy for manufacture, we envision it may find numerous applications in electromagnetics such as broadband scattering reduction and electromagnetic energy harvesting.
Project supported by National Natural Science Foundation of China; Natural Science Foundation of Shanghai Pujiang Program; Natural Science Basic Research Plan.