Abstract: A backfire feed antenna has a parabolic reflector with a ring-focus at the reflector focal point comprising a dielectric waveguide having a stem portion and a cap portion with a pointed end and most of the stem portion inside a conducting tube along the axis of the parabolic reflector. The outer surface of the cap portion is concave outward and convex inward and covered with a conducting layer. A curve between a parabola and hyperbola defines the surface. The cap portion has a conical surface extending between an annular surface at the junction between the stem portion and the cap portion and an axially extending circumferential surface surrounding the conducting layer. The inside end of the dielectric waveguide is pointed.