An ionic liquid-based ultra-broadband absorber with temperature stability, polarization insensitivity, and wide incident angle

In this paper, an ultra-broadband absorber based on ionic liquids is proposed. It is an absorber that is a fully enclosed resin container, and the container is filled with an ionic liquid 1-ethyl-3-methylimidazolium dicyanamide ([EMIM][N(CN)(2)]) with a circular cross-section. Simulation results show that the single-ring absorber can achieve more than 90% absorption in the microwave range of 12.25-50 GHz, and the relative bandwidth reaches 121.29%. Based on the theories of equivalent medium and impedance matching, the mechanism of broadband absorption is explored by analyzing the electromagnetic field distribution and power loss density of the absorber. In addition, the absorber exhibits good thermal stability in the range of 20 degrees C-100 degrees C, and has the characteristics of polarization insensitivity and wide incident angle. The proposed metamaterial absorber can be fabricated at a low cost, is environment-friendly, and may find potential applications in the fields of electromagnetic energy harvesting and stealth technology.