Broadband microwave absorption utilizing water-based metamaterial structures

In this paper, broadband microwave absorbers utilizing water-based metamaterial structure elements have been proposed and investigated. We employ water into the metamaterial structure unit-cell of the absorber as primary resonant elements such as the water-droplet, or water-tube structure. By investigating the resonant modes and the coupling between the water elements and the surrounding dielectrics, it is found the inherent multi-resonance of the proposed metamaterial structures could result in a broadband microwave absorption. For water-droplets design, 90% microwave absorption has been achieved from 7.5 GHz to 15 GHz, while for water-tube design, a much broader bandwidth from 5 GHz to 15 GHz is obtained for nearly 90% microwave absorption. The broadband absorption performance has been verified by both full wave simulation and experimental measurement. We believe the proposed broadband water-based absorber may find some applications in microwave stealth and electromagnetic compatibility technology.