The role of ideal and inclusion-made Single NeGative Metamaterials to achieve the extraordinary transmission through a sub-wavelength hole

In this contribution, we propose a new metamaterial-based setup to increase the transmission through a sub- wavelength hole. Conventional setups are based on the excitation of suitable leaky modes supported by the metallic screen hosting the hole. Periodic corrugations placed on the screen allow to excite such modes. On the other hand, the employment of dedicated covers made by metamaterials with constitutive parameter values close to zero has been also shown to be effective to enhance the transmission through the hole. In order to squeeze the dimensions of the covers, a suitable pairing of Single NeGative metamaterials has been recently proposed. However, all these techniques based on the excitation of leaky modes either propagating on the screen or along the metamaterial slab(s) require a quite large area around the sub-wavelength hole where to host the corrugations or place the covers. The setups we propose in this contribution, instead, are again based on the employment of Single NeGative metamaterials, but they do not require the excitation of the leaky modes. For this reason, the area occupied by the cover is of the same order of magnitude of the hole. The role of the Single NeGative metamaterial cover is presented in the paper, along with the analytical formulation and some numerical results showing the effectiveness of the proposed setups.