A pattern synthesis technique to compensate for distortions in large reflector antennas

Surface errors on parabolic reflector antennas degrade the overall performance of the antenna. An approach to electromagnetic compensation that uses pattern synthesis to compensate for the surface errors is presented. It differs from previous methods in two major respects. The previous studies used a global algorithm that attempts to correct the entire focal plane field. The pattern synthesis approach uses a localized algorithm in which pattern corrections are directed specifically towards portions of the pattern requiring improvement. The second major difference is that the pattern synthesis technique does not require knowledge of the reflector surface, but instead uses radiation pattern data to perform the compensation. Amplitude-only measurements can be used to determine the relative phase with reasonable accuracy at the location of the pattern distortions. Once the relative phase is known, the weighting of the auxiliary beams can be determined for compensation. Results from a specific application of the compensation technique are presented.<>