Abstract:
This paper addresses the issue of cross-polarized field components of an array of antennas as compared to that of individual elements of the array. For a single antenna, the co- and cross-polarization components are completely correlated in terms of phase and amplitude in a given direction. The co/cross-pol relations vary as a function of angular position from peak of the beam, which is important when there is pointing error. More specifically, for the reflector antennas, this relation might vary as the antenna points in different directions in azimuth and elevation, due to the changes in gravity profile, wind effects, temperature changes, etc., on the surface and feed/sub/main reflector alignment. In an array environment, these changes will vary among various antennas in the array, and indeed very small mechanical and design variations in the antenna elements (in terms of feed horns, feed/reflector misalignments, surface variations, etc., will contribute to the cross polarization variations.
