An Ultrawideband and Wide-Angle Absorber Based on Mushroom-Type High Impedance Surface

This letter proposes an ultrawideband, wide-angle absorber based on mushroom-type high impedance surface (HIS). The absorber is composed of six frequency selective surface (FSS) layers and six polymethyl acrylamide (PMI) foam substrates. The metal column is introduced into substrates to obtain a stable absorption within the broad oblique incidence angle <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">θ</i> range of 0° to 70° under TM polarization. Additionally, the absorber also has good absorption performance of the incident angle <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">θ</i> in the range of 0° to 55° under TE polarization. Good agreement can be obtained between the simulated and experimental results, which indicates that the absorber has an absorption of at least 90% within the frequency range of 1.18 GHz to 41.43 GHz, boasting fractional bandwidth (FBW) of 188.9%, and the thickness is only 0.116<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">${{\lambda }_{\max}}$</tex-math></inline-formula>.