Dual-band Polarization-insensitive High-efficiency Metamaterial Absorber for ISM-Band Biomedical Applications

The design, optimization, fabrication, and measurement of a dual-band, metamaterial-based polarization-insensitive, high-efficiency signal absorber in the 2.38–5.81 GHz frequency range of the ISM band is presented. The primary objective of this study is to design a microstrip absorber that is compact and simple, and therefore provides low fabrication errors and ease of integration. To achieve this goal, a comprehensive investigation is conducted to optimize the patch geometry to exhibit metamaterial characteristics, thus harnessing the signal-focusing capability. Another goal of this study was to achieve polarization independence, which poses an additional challenge. This was achieved simultaneously by achieving overlapping structural symmetry with the metamaterial properties. Additionally, various design parameters, such as substrate thickness and material selection, are explored, and their optimum values are determined through numerous simulation studies. Accordingly, the proposed absorber is fabricated based on the optimum simulated values. The measurement and simulation results are in good agreement with each other. Finally, the proposed structure is compared with other metamaterial absorbers operating in the same frequency range reported in the literature, presented in a comparative table, and its performance superiority is demonstrated.