Cross-Polarized current analysis and control for parabolic reflector antennas

Analysis are presented for the current distribution and its effects on the radiated fields from any portion of the parabolic reflector, using a generalized feed source. The feed is formed of co-polarized electric and magnetic sources, with a given directivity towards the reflector surface. The mixture ratio between the electric and magnetic sources is examined with a view to minimize the cross-polarized radia-tion. This ratio is dependent on the reflector configuration. While it is well known that cross-polarized cur-rents vanish when the electric and magnetic moments of the feed are equal in symmetric reflectors, no comprehensive analyses are available for offset configurations. Therefore, in this work generalized rigor-ous analyses are given to specially accommodate offset reflectors, which are widely used in modem tele-communication systems. Cross-polarized currents of offset reflectors could only be minimized. Feed pointing would be lower than the reflector center (mid way between this center and the vertex). Also, the feed source should be predominantly electric for vertical polarization and predominantly magnetic for horizontal polarization. Illustrations based on computer simulation are presented to give quantitative perspective for these results