Broadband metasurface absorber based on involute structure and surface plasmon resonance

Conventional wave absorbers face challenges concerning their volumes and limited absorption efficiency. While metasurface-based absorbers have achieved breakthroughs in thickness reduction and absorption enhancement, their narrowband characteristics restrict broader applications. In this study, inspired by geometric involute, a metasurface structure, which can generate multiple localized surface plasmon resonances (LSPR) at different frequencies within a single unit for broadening the absorption bandwidth, is proposed. Simulations and experiments are conducted, demonstrating that the proposed design can reach an absorption bandwidth of 20-28.2 GHz with an efficiency greater than 10 dB and a thickness of only 1.67 mm (approximately one-ninth of the wavelength at the lowest operating frequency). Thus, it exhibits ultrathin characteristics. A further analysis shows that the metasurface maintains a stable absorption performance for polarization and incident angles, with an absorption of almost 10 dB for polarization angle changes of less than 50°, or for incidence angles of almost 60°. This provides what we believe to be a novel solution for the design of broadband absorbers.