Dish-shaped radio beacons send tracking signals from Echo

TWO space-borne radio beacons, each about the size and shape of an ordinary dinner plate and equipped with a halfounce radio transmitter no larger than a cigarette lighter, are sending back the signals that enable ground stations to track the Echo balloon satellite as it circles the earth. The radio beacons were specially developed by the Radio Corporation of America (RCA) for the National Aeronautics and Space Administration (NASA).