Design of Polarization Insensitive Frequency Selective Absorber for Ku/K-bands

In this paper, a 2D structure frequency selective absorber is investigated. The structure is made up of two layers. First layer is a lossy metal structure at the top of the substrate. Second layer is a metallic ground placed at suitable distance and separated by air gap from the top layer to provide optimum absorption. The top layer is a modification of Hlibert-Curve array. The absorption band is from 17.58 GHz to 20.75 GHz, lying in Ku and K band for 90% absorptivity. There are two peaks of absorption, at 18.17 GHz with 99.7% and 20.24 GHz with 98.7% absorptivity. Due to symmetry in the structure of Hilbert-curve array, the absorber is insensitive to polarization. The proposed frequency selective absorber maintains absorption for upto 20° under oblique incidence of the incident wave.