A device for shielding at least one sub-wavelength-scale object (10) from an electromagnetic wave (20), which is incident on said device, comprises at least one layer of a dielectric material (Media 1), a surface of which having at least one abrupt change of level forming a step. At least a lower and lateral part of said surface with respect to said step is in contact with a medium (111) having arefractive index (n2) lower than that (n1) of said dielectric material. Said at least one sub-wavelength-scale object (10) is located within said device in a quiet zone (QZ) where an electromagnetic field intensity is below a threshold, said quiet zone extending above said surface, in the vicinity of said step, in a direction of incidence of said electromagnetic wave (20).