Primary-feed elements for multiple and contoured beam satellite antennas

The characteristics of possible feed candidates for contoured or multiple beam satellite antennas are considered, and the results of an extensive measurement program undertaken to establish the vector radiation characteristics of preferred feed geometries when embedded in a cluster of seven elements are reported. Dominant mode square or rectangular horns, dominant mode conical horns, and hexagonal waveguide horns are discussed as alternative means of achieving aperture dimensions close to a wavelength. Primary feed elements with hexagonal cross-section allow a tightly packed configuration in a honey-comb structure. The results of comparison measurements on two seven-element clusters, one comprising circular elements and the other hexagonal, are presented. The characteristics of the measured radiation patterns are discussed for both linear and horizontal polarization. The hexagonal elements generally tend to result in better vector radiation characteristics.