The shape of a cross section of a satellite TV antenna is a parabola. The shape of the antenna is a paraboloid. The 'dish' part of the antenna is really just a reflective surface. The actual antenna is the object held up in the center by an arm that comes off the side of the dish. The antenna is positioned at the focus. Any energy that is parallel to the axis of the parabola will reflect back to the focus of the parabola regardless of where the energy strikes the surface.
