An optimized dual polarization global beam antenna

A satellite antenna has been developed which provides, from a synchronous orbit position, a shaped beam for earth coverage with improved gain and a high degree of polarization purity. This shaped beam antenna is somewhat larger than the conventional global coverage horn antenna. However, for a fixed e.i.r.p. requirement, the increased gain can lead to a significant mass reduction due to decreased power requirements. Three types of antennas are described which are capable of providing the desired beam shape. However, only one of these antennas, the concentric array of horns, is consistent with the high degree of polarization purity desired. The design of the array and the results of the pattern measurements are presented.