English: Illustration of the effect of feed antenna gain on the "spillover" in a parabolic antenna. Spillover is the radiation from the feed antenna that falls outside the edge of the parabolic dish and is wasted. In the illustrations, the spheroid shape is the radiation pattern of the feed antenna, which is at its center. Only the radiation within the angle subtended by the dish, the shaded sector, is reflected by the dish and contributes to the main beam. The three drawings illustrate the effect of progressively higher gain feed antennas. As gain increases, less of the feed's energy is emitted at large angles to the axis, so there is less spillover.