Ultrathin absorber with tunable perfect absorption angle based on anisotropic ε-near-zero metamaterials

In this paper, an analytical solution shows that an ultrathin anisotropic ε-near-zero (AENZ) metamaterial (MM) layer backed by a metallic substrate can perfectly absorb an incident plane wave at a critical angle. The perfect absorption angle can be controlled by changing the loss of the AENZ MMs. An ultrathin microwave absorber is designed using meander-line MMs with a thickness of only λ/29. By changing the conductivity of metal in the MMs, the perfect absorption angle can be tuned from 20° to 50° at 10.2GHz.