Feed error effects on lens performance

In order to determine the mechanical alignment requirements for the feed assembly for a large space fed microwave lens, an analysis was performed that predicts the effect of feed errors upon lens performance. The antenna model that was analyzed consists of a small linear array for the feed and a large linear array for the lens. Effects of both transverse and longitudinal feed displacement, tilt, and phase error upon lens RF performance are examined. Results show that sensitivity of antenna gain and sidelobe level to phase and amplitude errors in the lens illumination due to feed position error. Low sidelobe antennas are shown to be particularly sensitive to these errors. The results of this error study suggest the need for active feed and lens correction techniques for low sidelobe space fed lens antennas. Preliminary results of phase-only and phase-amplitude correction applied at the lens and at the feed and lens are given.