Design and Analysis of a Compact Polarization-Independent Six-Band Metamaterial Absorber for Microwave Applications

Metamaterials are artificially engineered structures that exhibit electromagnetic properties not normally found in natural materials, such as negative permittivity and permeability. These unique characteristics make metamaterials highly useful for electromagnetic wave absorption applications. In this paper, a compact six-band metamaterial absorber operating in the microwave frequency range is proposed and analyzed. The designed absorber consists of a symmetric metallic patch structure printed on a lossy FR-4 dielectric substrate, backed by a copper ground plane to eliminate transmission. The proposed unit cell supports six distinct resonance frequencies at 2.76 GHz, 6.25 GHz, 11.54 GHz, 13.28 GHz, 15.73 GHz, and 17.38 GHz, achieving absorption levels greater than 92% at all bands, with peak absorption exceeding 99%. Due to the symmetric geometry, the absorber exhibits polarization-independent behavior under normal incidence. Additionally, the structure demonstrates angular stability for incident angles up to 45° over a wide frequency range. The absorption mechanism is explained using normalized impedance matching, surface current distribution, and electric field analysis. The simulation results confirm that near-unity absorption occurs when the effective impedance of the metamaterial matches the free-space impedance. The entire design and performance evaluation are carried out using CST Microwave Studio 2018. Owing to its compact size, multi-band operation, polarization insensitivity, and high absorption efficiency, the proposed metamaterial absorber is suitable for applications such as electromagnetic interference shielding, radar cross-section reduction, sensors, and microwave communication systems.