The ornamental design for an ultra-wideband horn antenna, as shown and described.
FIG. 1 is a perspective view of an ultra-wideband horn antenna design showing my new design.
FIG. 2 is a front view of an ultra-wideband horn antenna.
FIG. 3 is a rear view of an ultra-wideband horn antenna.
FIG. 4 is a right side view of an ultra-wideband horn antenna.
FIG. 5 is a left side view of an ultra-wideband horn antenna.
FIG. 6 is a top view of an ultra-wideband horn antenna; and,
FIG. 7 is a bottom view of an ultra-wideband horn antenna.
Any shading and cross-hatching are not features of the design but are utilized to illustrate the surface contours of the ultra-wideband horn antenna design in the drawings.
The broken lines depict portions of the ultra-wideband horn antenna that form no part of the claimed design.