A lens antenna including at least one diffractive dielectric component capable of shaping a microwave frequency wavefront having a wavelength comprised in a range from 1 mm to 50 centimeters, wherein said diffractive dielectric component includes a plurality of main microstructures formed in a substrate material with a substrate refractive index (ns) so as to form an artificial material with an effective refractive index (n), each main microstructure having a size (d) smaller than a target wavelength (λ0) taken from said range of wavelengths, said main microstructures being laid out per zones, so as to make a surface filling level vary, the effective refractive index (n) being a function of said surface filling level, the layout being such that the effective refractive index (n) varies inside said one zone of said diffractive dielectric component quasi monotonously between a minimum value and a maximum value less than or equal to the substrate refractive index (ns).