Modification of horn antennas for low sidelobe levels

Four modified horn antennas with greatly reduced backlobes are described. The principal method of reducing backlobes consists of preventing the energy from illuminating the edges from which it is diffracted into the back regions. The mechanism for forcing energy away from these edges is the use of microwave absorber material, choke slots, and corrugated surfaces. An additional feature of these devices is an extremely smooth main beam with no discernible sidelobes.