Ultra-broadband, high absorption, polarization-insensitive microwave absorbers designed based on multi-scale fractal metasurfaces

Abstract

Microwave absorbers play an essential role in radar stealth applications. However, conventional microwave absorbers are hindered by limitations such as narrow bandwidth, large size, and inadequate absorption rates. Leveraging metasurfaces presents an ideal approach for creating microwave absorbers, but metasurface-based broadband absorbers typically entail intricate structures, natural absorbing materials, or electronic components, posing challenges in terms of fabrication and expansion. Here, we numerically demonstrate a simple multi-scale fractal metasurface microwave absorber, with the full width at half-maximum of band exceeding one optical octave. By integrating the localized surface plasmon resonance absorption band and the Salisbury-Screen-type absorption band, we achieve an average absorption of 90% ranging from 11.5 GHz to 27.1 GHz. Furthermore, this absorber exhibits excellent polarization insensitivity and maintains high absorption even at large incident angles. The device, offering both broadband absorption and a straightforward structure, holds significant promise for practical applications and widespread adoption.