Compensation of the beam squint in axially symmetric, large dual reflector antennas with large-ranging laterally displaced feeds

The beam squint in axially symmetric reflector antennas with laterally displaced feeds is manifested by a small shift of the radiation patterns for left- and right-hand circular polarization. It is caused by the cross-polarized component in the reflected field. The authors´ interest in this effect, and especially in how to minimize or to compensate for it, was stimulated by some measurements with the 100-m radio telescope of the Max-Planck-Institut fuer Radioastronomie. They have carried out a series of computer simulations for different geometrical antenna configurations for the Cassegrain optics. The presented results show that depending upon various geometrical antenna parameter values, while keeping the laterally displaced feed in a gain optimized orientation, i.e., directed to the primary focus, the angular shift between the squinted beams can even reverse. This offers the chance to compensate the beam squint for large range lateral displacement of the feed by choosing an appropriate antenna/feed configuration