Multiband polarization-insensitive cartwheel metamaterial absorber

Metamaterials are specifically engineered to produce electromagnetic properties that are not available in natural materials. Multiband metamaterial (MM) absorbers achieve great research interest due to their applications in sensing, filtering, and stealth. These absorbers are mostly made of multilayered and complex geometrical structures. In this work, a single-layered cartwheel-shaped (CWS), polarization-insensitive MM absorber operating in the microwave band is proposed. The absorber is discovered at four main resonance peaks at 13.64, 17.15, 18.4, and 19.23 GHz with an absorptivity above 0.9. It shows good angular stability, and multiple absorption peaks are attained due to multiple electric and magnetic resonances. Its characteristic has not been changed under different polarizations of incidence wave studied as 0°, 15°, 30°, 45°, 60° and 75°. When the absorber is examined with respect to the obliquity of the incidence wave in both TE and TM modes, the prominent absorption peaks exhibit an absorption performance above a ratio of 80%. Moreover, absorption characteristics can be tuned by modifying the substrate thickness. The comparison of simulated results and measured results shows good agreement with each other. This absorber would be useful for sensing and filtering applications in microwave devices.