Polarization Controlled Ultrathin Quad Band Microwave Absorber for X and C-Bands

A polarization-controlled ultrathin quad-band metamaterial absorber has been proposed in this paper for X and C-Band applications. The given absorber consists of circular resonators and circular ring resonators at each corner, a rectangular resonator at the edges, an annular ring resonator and a star-shaped resonator at middle of the novel geometry. The resonators are mounted over an FR4 dielectric substrate having a thickness of 0.6mm completely backed with copper of thickness 0.035mm. The novel geometry shows peak absorption of 98.96%, 98.61%, 95.21%, and 99.81% at the frequencies of 6.3GHz, 8.3GHz, 10.2GHz, and 11.1GHz respectively. The unit cell geometry has full-width half maxima (FWHM) for the center frequencies of 230 MHz (6.41-6.18 GHz), 300 MHz (8.46-8.16 GHz), 330 MHz (10.39-10.06 GHz), and 490 MHz (11.39 - 10.9 GHz) for the four absorption peaks. The four-fold symmetry of the structure ensures the polarization-controlled behavior. The surface current distribution is also carried out for both the upper most and lower most surfaces of the presented geometry. The geometry is also examined for both transverse-magnetic (TM) and transverse-electric (TE) polarization mode plotting 45° of angle of incident.