Preliminary study on offset scan-corrected reflector antenna system

Preliminary study on offset shaped dual reflector antenna systems has been carried out to assess the feasibility for multibeam satellite applications. The two-dimensional offset shaped reflector antenna geometry is generated by first creating the nodal points according to a bifocal condition and then connecting the nodal points by smooth curves to form the profiles of the main and subreflectors. The three-dimensional geometry is created by body revolution. The offset geometry is obtained by properly tailoring the three-dimensional geometry. This offset shaped reflector antenna system has an inherent astigmatism which can be either fully or partially compensated. For applications requiring a scan range in azimuth more than
\pm 5
beamwidths, the offset shaped dual reflector antenna systems offer better scan performance (in terms of peak gains) than offset Cassegrain geometries at the expense of the performance of the on-axis beams. In elevation with a 16 beamwidth scan range, the shaped design provides 0.3 dB less scan loss than the Cassegrain design.