Design of a High-Efficiency, Polarization-Insensitive Quad-Band Metasurface Absorber for Microwave Applications

In this study, a multi-band, high-absorption, polarization- and angle-insensitive metasurface absorber (MSA) was designed for potential use in defense industry applications. In this context, a metasurface absorber capable of achieving high absorption at four distinct resonance frequencies was proposed. Electromagnetic (EM) simulations of the proposed metasurface absorber (MSA) were performed using CST Microwave Studio (CST). According to the simulation results, the absorber achieved absorption rates of 99.8%, 99.9%, 96.9%, and 99.02% at 3.5 GHz, 7.1 GHz, 9.4 GHz, and 13.7 GHz, respectively. These resonance frequencies correspond to the S, C, X, and Ku bands, demonstrating that the design effectively operates across four different microwave bands and exhibits strong multi-band absorption characteristics. Due to the symmetric geometry of the metamaterial structure, the absorber exhibited nearly identical performance under both TE and TM polarization modes, confirming the polarization-insensitive behavior of the proposed design. Furthermore, angular stability analysis revealed that the absorber maintained absorption levels above 80% for incident angles up to 60°, indicating strong robustness and angle insensitivity. To provide a deeper understanding of the absorption mechanism, detailed analyses were conducted on the structure’s characteristic impedance, surface current distributions, and electric and magnetic field intensities at each resonance frequency. Additionally, to validate the simulation accuracy, an equivalent circuit model (ECM) of the proposed metasurface absorber was developed using the Advanced Design System (ADS), and the results were compared with those obtained from CST simulations.