A microwave wideband hyperlens based on metamaterials closed-rings

Hyperlens and superlens have been proven to overcome the “diffraction limit” to achieve subwavelength imaging. Previous works have done great performance, but they need one or more negative constitutive parameters, which are realized by metamaterials with resonance structures and can only work well for narrowband. In this letter, we design an improved microwave hyperlens which can be effective for a wideband using the metamaterials composed of closed-rings, with all the constitutive parameters positive. Both the simulation and experiment results show that we can use this kind of hyperlens to achieve subwavelength imaging with resolution up to 1/12 the vacuum wavelength.