Experimental Investigation on Water Based FSS Absorber

The performance of a low-cost frequency selective surface (FSS) water-based absorber at microwave band is experimentally investigated in this paper. The unit cell structure of the FSS consists of a very thin square box made of acrylic sheet material filled up with water and backed with a copper ground plane. The Periodicity of the unit cell is
$0.45\lambda_{l}$
and the overall thickness of the absorber is
$0.05\lambda_{l}$
, where
$\lambda_{l}$
is the wavelength at the lowest operating frequency. The fractional bandwidth (FBW) of the proposed absorber is 17.14% at −10 dB reflection. The proposed absorber depicts an absorption of more than 90% in the frequency range of 3.2 GHz to 3.8 GHz at different angles of polarization.