An ultra-thin polarization independent metamaterial absorber for triple band applications

This paper presents an ultra-thin polarization independent metamaterial microwave absorber comprising of three concentric closed ring resonators (CRR). The unit cell sizes as well as the other geometrical dimensions like radii and widths of the rings are optimized so that absorptions take place at three distinct frequencies near to the middle of the FCC radar frequency spectrum. The proposed structure shows absorptivities of 94.1%, 99.6% and 99.4% at 5.5 GHz, 9.52 GHz and 13.8 GHz respectively. The proposed structure has been studied under oblique incidence, both for TE and TM polarization where it behaves as absorber upto 60 ° incident angles in both the cases. Due to the geometrical symmetry, the structure is found to be polarization independent absorber.