Ultra-Wide Band Metamaterial Absorber Based on Resistive Sheet for L to Ku Band Application

In this work, the design of an ultra-wideband polarization-insensitive metamaterial absorber for L-band to Ku-band frequency application is investigated. The Unit cell of the metamaterial absorber consists of two ohmic sheet layers, in which one ohmic sheet of square shape is sandwiched between two thin substrates and another ohmic sheet of square shape is placed on the top of dielectric substrate. Due to its four-fold symmetry, the design yields polarization-insensitive characteristics in the desired band. More than 90% absorptivity from 1 GHz to 15 GHz has wide fractional bandwidth of 175% concerning the center frequency. The unit cell structure has a peak absorptivity of 98.6% at 2.24 GHz. The proposed structure has more than 90% absorption in both TE and TM modes at normal incidence. The structure also provides more than 80% wide absorption at incident angle up to $\theta =45^{\circ}$ for both TE and TM modes. Ultra-wideband response of the absorber with polarization-insensitive makes it commercially suitable for applications ranging from L Band to Ku Band.