A ultra-wideband thin microwave absorber using inkjet-printed Frequency Selective Surfaces combining carbon nanotubes and magnetic nanoparticles

A ultra-wideband microwave absorber (UWMA) combining Frequency-Selective-Surfaces (FSS) and dielectric layers is proposed. FSS patterns are printed by inkjet on dielectric layers using a resistive magnetic ink made of suspended carbon nanotubes decorated with F e 3 O 4 nanoparticles. The UWMA exhibits a huge fractional bandwidth of 140%, corresponding to reflec-tivity lower than-10 dB and absorption higher than 90%, observed from 7 GHz to 43 GHz, meaning a 36 GHz bandwidth, for a thickness of only 0.26 λ. This performance is achieved through a proper selection of FSS surface resistance, tuned by the number of printed layers. Excellent agreement is observed between designed and measured low reflectivity and high absorption