A polarization-insensitive metamaterial absorber with broadband and tunable absorption based on resistive film and lumped elements

In this paper, using electromagnetic (EM) and circuit co-simulation, a design for a polarization-insensitive metamaterial absorber (MMA) based on the resistive film and lumped elements was investigated numerically. The bilayer resistive film enables MMA with broadband absorption from 2.1 GHz to 15.5 GHz. At the same time, the varactor diodes and resistors make the absorption peaks tunable in the L- and S-bands. With this approach, the compatibility of broadband absorption and tunability can be achieved without increasing the thickness. Finally, due to the symmetry of the structure, MMA can achieve extreme polarization insensitivity for both transverse electric (TE) and transverse magnetic (TM) polarizations.