A Broadband Flexible Metamaterial Absorber Based on Double Resonance

We present a broadband microwave metamaterial (MM) absorber, the unit cell of which consists of a lumped-resistor-loaded electric-inductive-capacitive (ELC) resonator and a cut-wire on the same side of a flexible polyimide substrate. In contrast to the common MM absorber, the metallic pattern layer of the proposed structure is placed parallel to the direction of propagation of the incident wave in order to reduce the radar cross-section (RCS) at frequencies other than the targeted frequency bands. Our experiments show that the proposed absorber exhibits a peak absorption rate of 92% and 93% at 8.6 GHz and 13.4 GHz, respectively, and 88% of the full-width at half-maximum (FWHM) bandwidth is achieved.