A Broadband Microwave Metamaterial Absorber with Octave Bandwidth

In this paper, a broadband metamaterial absorber has been presented for practical applications. The unit cell of the proposed structure comprises metallic patch of single circular split-ring imprinted on top surface of a metal-backed dielectric substrate. The geometrical dimensions of the structure have been optimized in such a way that the structure exhibits broadband absorptivity response of 9.12 GHz from 6.70 to 15.82 GHz with more than 90 % absorptivity. Three distinct absorption peaks are observed at 7.16, 10.74 and 14.96 GHz. The absorption phenomena at these three frequencies have been analyzed and the roles of several geometrical parameters involved in the design are investigated. The proposed structure has been studied under oblique incidence, both for TE and TM polarizations where it shows wideband absorption characteristics up to 30A degrees incident angle for TE polarization and 45A degrees incident angle for TM polarization. The proposed structure is very thin (similar to lambda/8.4 with respect to the centre frequency of absorption bandwidth) compared to the commercially available microwave absorbers.