Dual-band polarization-insensitive metamaterial inspired microwave absorber for LTE-band applications

Abstract

In this paper, the design, simulation and measurement of a dual-band polarizationinsensitive metamaterial inspired microwave absorber are presented. The unit cell is composed of two concentric closed ring resonator (CRR) structures forming octagonal rings which are carved on an FR-4 dielectric substrate to give maximum absorption at dual frequencies of 2.09 GHz and 2.54 GHz. At these frequencies, the minimum reflection coefficients of −29.15 dB and −18.76 dB are achieved with absorption rates of 99.88% and 98.67% and narrow 10 dB bandwidths of 2.62% and 2.76%, respectively. Microwave absorption property of the proposed absorber structure is simulated by setting the perfect electric boundary conditions in four planes whose surface normal vectors are directed perpendicular to the wave propagation direction. These numerical computation settings replicate the rectangular waveguide to be used in the experimental measurements for the comparison between the simulated and experimental results. It is experimentally verified by the waveguide measurement method that the absorption rates about 99% are achieved for dual bands with polarization insensitivity thereby meeting the absorption requirements of LTE-band frequencies for a real time microwave absorber based energy harvesting systems.