An investigation of offset-fed beams on the proposed SKA dishes with various degrees of shaping

The SKA dishes will be used with single pixel feeds (resulting in a single on-axis main beam) as well as phased array feeds that will generate multiple offset beams. The final optics will be shaped to improve the performance of the single pixel systems. This shaping may, however, be to the detriment of the offset beams of the multi-beam systems. It is important to understand the extent of this. A limited set of possible optics candidates for the Square Kilometre Array (SKA) was recently proposed. This paper investigates the electromagnetic performance of centre-fed and offset-fed feeds on a subset of these classical conic section dual reflector systems and also on shaped versions of these reflectors with various degrees of shaping.