Narrow multibeam satellite ground station antenna employing a linear array with a geosynchronous arc coverage of 60 deg. II - Antenna design

A dually polarized narrow (less than 0.5 deg) beam antenna which provides a geosynchronous arc coverage of 60 deg is proposed and analyzed. To track the geosynchronous arc accurately, the properly oriented antenna produces a conically scanned beam by means of a linear array of feed horns with bias ccut apertures illuminating a pair of parabolic cylinder reflectors in an imaging arrangement. This design, with reduced size array and singly curved reflectors, is relatively simple to construct. Calculations for a 0.35 deg beamwidth Ku band earth station antenna show a 0.05 deg pointing accuracy with scan loss due to aberrations less than 1 dB and little pattern degradation throughout the scan region. For multiple beam capability, a Rotman lens is proposed and analyzed as a means of exciting the feed array. It allows communication with multiple satellites spaced as close as 1 deg.