  Epsilon-near-zero (ENZ) materials, including artificial metamaterials, have
been advanced to mold laser beams and antenna-mediated radiated waves. Here we
propose an efficient method to control Ohmic losses inherent to natural ENZ
materials by the assembly of subwavelength structures in a nonperiodic matrix
constituting an ENZ metacoating. Implemented over plano-concave transparent
substrates whose radius can be of only a few wavelengths, ENZ surface-relief
elements demonstrate to adequately shape a plane wave into highly localized
fields. Furthermore, our proposal provides an energy efficiency even higher
than an ideally-lossless all-ENZ plano-concave lens. Our procedure is
satisfactory to generate aberration-free nonparaxial focused waves and
accelerating beams in miniaturized spaces.
