Reflector surface accuracy for shaped beam antennas

The influence of surface errors for three reflectors shaped for uniform circular coverage with half angles of 2°, 4° and 8°. The 4° case is compared with an equivalent multi-beam antenna. The results show that surface errors, which would cause a 0.1 dB peak gain loss for a focusing antenna, could reduce the coverage gain for a shaped beam antenna by 2 dB or more. The scaling of the results for antennas of differing diameter or correlation distance (surface roughness) is mentioned along with the applicability of the results to other cases. Some difficulties in estimating surface correlation also are noted