Polarization-Insensitive Dual-Band Switchable Absorber With Independent Switching

A dual-band switchable absorber is presented with independent switching of absorption frequencies. The unit cell of the proposed structure is composed of an annular ring and a cross-dipole, where switchable p-i-n diodes are embedded. By controlling the bias voltage of the diodes, both the absorption frequencies can be switched between two frequency bands independently, thereby resulting in a dual-band/bandwidth-enhanced absorber. Moreover, the proposed design is polarization-independent due to fourfold symmetry unlike the earlier reported switchable absorbers. A novel biasing network has also been developed for measuring the fabricated structure, which is experimentally verified under normal incidence.