Compact polarization-insensitive microwave metamaterial absorber with hepta-band characteristics

Abstract

Abstract This paper presents an ultra-thin and compact metamaterial absorber (MMA) capable of achieving near-perfect absorption peaks across the C, X, Ku, and K frequency bands. The MMA structure features a modified metallic plus-shaped resonator surrounded by symmetric L-shaped resonators within a compact size of 13 × 13 mm2. The absorber exhibits seven absorption peaks at different resonant frequencies including 4.23, 6.48, 10.62, 12.92, 14.03, 17.39, and 18.11 GHz. With a thickness of 0.0225λ and a compact size of 0.1833λ at the lowest frequency, the absorber offers remarkable thinness and compactness. Different characteristics of the absorber, such as normalized impedance, surface current distribution, and electric field distribution, are also examined. The polarization-insensitive behavior of the MMA is assessed through absorption and reflection responses under different polarization and incident angles. The Equivalent Circuit Model (ECM) of the metamaterial absorber is also designed to accurately represent the MMA unit cell across all resonant frequencies. Experimental validation of the proposed MMA confirms its performance consistency with simulation results. The proposed MMA design holds potential for applications in defense, detection, and sensing. The sensing ability of the MMA is analyzed using simulations at different refractive index values.