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A thin ultra-wideband microwave absorbing structure printed on flexible substrate with resistive-ink made of multiwall carbon-nanotube

In this paper, we present a ultra-wideband radar absorbing structure operating in 5–50GHz frequency range. Two layer of Frequency Selective Surfaces (FSS) separated by dielectric spacer and having 160 Ω/sq. and 80 Ω/sq. respectively are printed on flexible PC-sheet with home-made water-based MWCNT-ink. For a thickness of 5mm a measured reflection coefficient bandwidth below −15dB is achieved over a bandwidth of 31GHz between 9–40GHz band, and agrees very well with simulation. The higher absorption bandwidth of absorber at normal incidence is benefitted from the stacked gradient of optimized surface resistance of resistive-FSS structure separated by below Io/4 spacer besides the bandwidth of the proposed absorber combines flexibility and compactness.