In one embodiment, a parabolic antenna assembly includes a main reflector, a feed system in RF communication with the main reflector including a horn and a dielectric portion, and a sub-reflector in RF communication with the feed assembly, wherein the sub-reflector includes a body portion and a stem portion mechanically coupled to one another, wherein a reflecting surface of the sub-reflector is defined by at least a portion of the body portion and at least a portion of the stem portion, wherein the dielectric portion spaces the sub-reflector from the horn, and wherein the sub-reflector includes an axially-symmetric choke for providing virtual continuity at the reflecting surface.