Beam forming synthesis for South America coverage with a small primary feed array

Discusses the possibility of extending the formulation presented in Westcott and Zaporozhets (1993) to the synthesis of shaped reflectors illuminated by a feed array. This technique has then been applied to a small aperture offset reflector illuminated by a small feed array placed in the focal region, in order to generate a Ku band coverage beam for the South American continent with a minimum gain requirement of 26 dBi. The use of a small primary feed array results in a reduced distortion range of the initial parabolic reflector which in the case studied did not exceed /spl lambda//5 at the receive band. The results also show that the array geometrical configuration used for reflector shaping does not impose bandwidth limitations on the design. In addition to the simplicity of the design the use of a small cluster combined with a shaped reflector also offers the possibility of obtaining some degree of freedom when dealing with problems involving coverage beam reconfiguration, and of obtaining better roll-off characteristics for the radiated field pattern outside the desired coverage area.