Scan limits of off-axis fed parabolic reflectors

The scan limits of point-fed paraboloidal and line-fed parabolic-cylinder reflector antennas are derived for large reflectors of arbitrary focal-length-to-diameter ratio ( -number). A numerical approach is employed which incorporates the effects of all higher order spatial distortions (ray aberrations) normally neglected in previous analyses. The results demonstrate that paraboloids of large - number have substantially less scan capability than could be inferred from earlier analyses.