Thin Microwave Absorber Based on Laser-Induced Graphene Frequency Selective Surfaces

This study presents a pioneering approach to fabricating single-layer Frequency Selective Surfaces (FSS) using Laser-Induced Graphene (LIG). The FSS structure proposed consists of periodic resistive patterns of LIG synthesized through a one-step laser photothermal process directly on the surface of a thin polyimide substrate. The structural and electrical properties of LIG were thoroughly investigated to develop an electrical model aiming at optimizing the design and absorbing properties. After that, a 12 mm thick LIG-FSS microwave absorber prototype was fabricated and tested under real conditions, demonstrating over 90% absorption in the frequency band from 1.69 to 2.91 GHz with a thickness of only 0.068 times the maximum wavelength $(\lambda _{\mathrm{ max}})$ , demonstrating good agreement with the simulations and theoretical results. Additionally, we discuss the tunability of the frequency response of the absorber by adjusting accordingly the induced material’s properties. Finally, we also demonstrate the versatility of this approach for the fabrication of FSS structures based on alternative patterns. The findings presented in this work highlight the promising potential of sustainable microwave absorbers based on LIG-FSS structures.