Wide Oblique Incidence Insensitive Ultra-thin Dual-band Metamaterial Absorber

A very wide oblique angle insensitive, ultra-thin, low-cost, polarization-independent dual-band metamaterial ab-sorber is proposed in this article. The design consists of four concentric rings. The proposed absorber provides a dual-band at frequencies of 11.1 and 13.2 GHz having absorptivity of 97% and 98%. The structure also provides 400 and 450 MHz bandwidth at center frequencies with respect to full width half maximum value. The absorptivity remains unchanged to the polarization angles and the structure provides an absorptivity of more than 90% up to 85° of oblique incidence. Both impedance matching theory and resonant absorption theory are used for the analysis of the absorption mechanism. The equivalent circuit of the structure is designed by using lumped circuit theory. A comparison study on the performances of the structure with the previously proposed structure is provided at the end of the article.