Triband Metamaterial Absorber Based on a Three-Ring Coupled Structure

This paper investigates a triband metamaterial absorber based on a three-ring coupled structure. The unit cell of the absorber is composed of a square ring, a square circular ring, and a square patch resonator, exhibiting absorption peaks at 3.97, 6.85, and 10.11 GHz, with peak values reaching 99.72, 99.88, and 99.87%, respectively. Furthermore, the absorber is found to be polarization-insensitive and demonstrates wide-angle incidence characteristics. To further explore the absorption mechanism, the absorption curves of each individual ring structure are analyzed, and the influence of each resonant unit on the absorption performance is studied. A detailed analysis of the electric field distribution, surface current distribution, and equivalent impedance reveals that the absorption mechanism primarily depends on the impedance matching between the surface pattern layer and the incident electromagnetic wave as well as resonant absorption. This research provides an efficient and practical direction for the design of efficient absorbing materials.