Ultrathin Broadband Dual-Ring Metamaterial Absorber Based on Chip Resistance

Herein, an ideal metamaterial absorber with broadband, ultrathin, and wide incidence angle is proposed. The absorption unit of the proposed metamaterial absorber consists of two double rings. And, eight chip resistors are loaded between them to increase the absorption bandwidth. It is showed in the simulation results that the structure absorbs more than 90% in the range of 8.6-17.4 GHz at vertical incidence. The total thickness of the absorber is 2.4 mm (0.069 lambda(L)), where lambda(L) is the lowest-absorption frequency, smaller than the absorber structure of the same type of bandwidth. To understand the broadband absorption performance of this absorber, the effects of design parameters such as substrate thickness and resistive resistance are investigated. In addition, herein, to investigate the absorption mechanism of this absorber, the normalized impedance, electric field distribution, and surface current density are demonstrated. Finally, the absorber is fabricated and measured at vertical incidence, and the experimental results are in good agreement with the simulation results.