Design, fabrication and measurement of a broadband polarization-insensitive metamaterial absorber based on lumped elements

A broadband metamaterial absorber (MA) based on lumped elements is presented, which is composed of the dielectric substrate sandwiched with metal split-coin resonators (SCR) welded with lumped elements and continuous metal film. We simulated, fabricated, and measured the lumped elements MA. Compared with the single SCR structure MA, the composite MA loaded with lumped elements has a wider absorptivity and works in a lower frequency. The experiment results show that the bandwidth of absorption of 90% is about 1.5 GHz and the full width at half maximum (FWHM) can be up to 50%, the absorptivity is also nearly unchanged for different polarizations. The further simulations of the absorptivity of composite MA with different lumped resistances and capacitances indicate that there exist optimal values for lumped resistances and capacitances, where the absorptivity is the highest and the bandwidth is the widest.