A dihedral shaped device is provided, which includes two plates forming between them an angle of [pi]−2[alpha], where 0<[alpha]<[pi]/4. Each plate has a ground plane, at least one dielectric layer and a network of radiating elements. An incident wave is reflected by the device by virtue of a double reflection from both plates. The network of radiating elements of each plate allows a phase shift to be generated, from the exterior towards the centre of the dihedron, along an axis perpendicular to an axis of intersection of the two plates, according to a set phase law, allowing a deviation to be introduced relative to a specular reflection for a given operating frequency.