An Ultrawideband and Ultralow Scattering ITO Absorber Under Wide-Angle Incidences

This letter presents an ultrawideband, ultralow scattering, dual-polarized, and lightweight absorber under wide-angle incidences, which utilizes multilayer indium tin oxide (ITO) films. Based on the multimode resonance (MR) and ultra-wideband impedance matching (UWIM) absorption principles, ITO square ring patterns with different sizes are configured in a pyramid shape on eight layers of foam substrate. Under normal incidence, the absorption rates of transverse electric (TE) waves and transverse magnetic (TM) waves for the ITO absorber exceed 99% from 1.9 to 40.4 GHz [the fractional bandwidth (FBW) is 182.03%], covering the S, C, X, Ku, K and Ka microwave bands. Under oblique incidence covering a 60° range, the ITO absorber exhibits over 90% absorption for TE waves within 3.6–43.1 GHz (169.2%). Similarly, it demonstrates over 90% absorption for TM waves in 3.06–43 GHz (173.4%). To investigate the absorption mechanism of the ITO absorber, a detailed analysis of its surface current distribution and equivalent circuit model (ECM) is conducted. Finally, an ITO absorber prototype with dimensions of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$300\times 300$</tex-math> </inline-formula> mm<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> is fabricated. The simulated and measured results are in good agreement.