On Fabry-Perot resonances of a wire-medium hyperlens

As it was recently shown an array of slightly diverging metal wires called wire-medium hyperlens can be used for the significant and very broadband enhancement of the radiation of small sources. Really, in the domain around the source the array operates as an infinite wire medium and near its effective surface it is well matched to free space that implies the gain in the far-field radiation. However, the matching on the surface is imperfect and implies dimensional resonances of Fabry-Perot type. The impact of these resonances and the frequency-averaged enhancement of dipole radiation in the wire-medium hyperlens is studied in the present paper.