Dual offset reflectors shaped for zero crosspolarisation with asymmetric feed pattern

The design of shaped dual offset reflectors to produce a zero crosspolarised parallel beam is re-examined. Geometrical optics is used to show that the shaping can compensate not only for system asymmetry but also for a limited amount of source-pattern asymmetry. An analytical method is presented which enables constraints to be applied, to guarantee single-valued reflectors.