A polarization insensitive compact ultrathin wide-angle penta-band metamaterial absorber

Abstract

In this paper, the design, fabrication, and measurements of a compact ultrathin five-band metamaterial absorber with wide-angle stability have been presented. The unit cell of the absorber consists of five concentric metallic circular rings printed as the top layer of a grounded dielectric substrate of thickness 1 mm. The radii and the intermediate gap between the rings are optimized such that the proposed absorber exhibits five distinct absorption peaks at frequencies of 5.28, 7.36, 9.52, 12.64, and 16.32 GHz with absorptivities of 92.03, 90.46, 95.10, 91.65, and 91.10%, respectively. The proposed absorber is polarization insensitive for both TE and TM incident wave and results high absorption for wide incidence angle up to 60°. The proposed structure is compact with its unit cell size of 0.54 λ₀ and ultrathin with thickness of ~λ₀/19 corresponding to the highest frequency of absorption. Surface current and field distributions are studied to understand the absorption mechanism. A prototype of the proposed absorber is fabricated and experimentally tested for different polarization and incident angles. The measured results are observed to be in agreement with the simulated ones. The proposed absorber is suitable for potential applications due to its multi-band absorption.

Keywords:

• Metamaterial absorber
• multi-band
• polarization insensitive
• compact
• ultrathin

Acknowledgments

The authors want to thank Mr. Saptarshi Gosh (Ph.D. Scholar, Electrical engineering, IIT Kanpur, India) for the valuable suggestions in the measurements of fabricated sample.