A low cost all-dielectric water based resonant absorber

A promising technique for lowering interference is to absorb electromagnetic (EM) energy and partially transform it into heat. EM absorbers are able to achieve this phenomenon. Most electromagnetic absorbers are based on metamaterials and can absorb a broad range of frequencies. However, for specific applications, a resonant absorber is needed. In this paper, a purely water based, frequency selective surface (FSS) resonant absorber is proposed. The structural design of the proposed absorber consists of an array of square shaped cavities made of acrylic sheet for holding the water. The ground plane made of conducting foil/tape is placed at the bottom. The dimension of the unit cell is 0.45\(\lambda _l\)\(\times\) 0.45\(\lambda _l\)\(\times\) 0.05\(\lambda _l\) where, \(\lambda _l\) is the wavelength at the lowest operating frequency. The EM absorber shows more than 99.99\(\%\) absorption and 17.14\(\%\) fractional bandwidth (FBW) at resonating frequency of 3.5 GHz at different polarization angles, make it suitable for WiMax/CBRS/n78 5G band application. The performance of the proposed absorber is analyzed both through simulation and measurement. A comparison between the simulated and the measured results shows good agreement.