The present invention relates to ultra-wideband (UWB) directional circular-field-polarization antennae. The technical result consists in development of a UWB antenna in which a unidirectional radiation is naturally generated within a wide or ultra-wide frequency band and generally does not require the use of an absorber on a back side of a radiating element. The UWB antenna comprises: a dielectric substrate; at least one feed line formed on the dielectric substrate; a spiral radiating element formed on the substrate and coupled to said at least one feed line; at least one additional dielectric substrate arranged in parallel with and above said dielectric substrate, wherein a flat printed cavity of an axially-symmetric shape is formed on said at least one additional dielectric substrate, said cavity being arranged coaxially with the spiral radiating element.