Absorption Peak Controlled Low-Frequency Wideband Flexible FSS Absorber

This article presents an ultrathin absorber for lower microwave frequency applications. The structure is designed using a thin dielectric substrate and a commercially available magnetic sheet superstrate. Due to its low thickness, it is suitable for both planar and conformal applications. For the normal incidence of the electromagnetic wave, the measured reflectivity (R)≤–10 dB extends from 1.75–3.4 and 1.7–3.36 GHz in the transverse electric (TE) and the transverse magnetic (TM) modes, respectively. All these have been achieved for a total thickness of 0.023λLwhereλLis the wavelength corresponding to the lowest operating frequency. Due to the low thickness, the structure has been bent around a cylindrical base. In the conformal design, with the decrease in the curvature radius, in comparison to the planar structure, the bandwidth expansion has been observed. The equivalent circuit model of the structure has also been rigorously analyzed to understand the behavior of the magnetic sheet superstrate and the dielectric substrate. The absorption peaks (fAPs) in the operating band have been noticed. At the normal incidence, against the simulatedfAPsof reflectivity magnitude≈−20 dB, the measuredfAPs≈−22 dB, and≈−30 dB in TE and TM modes, respectively, have been obtained.