Left: response patterns on the sky of the individual Vivaldi elements of the PAF. Each panel covers the same 3° ×3° on the sky and shows the primary beam of a given element. Right: response of CBs formed in the same directions of the element beams. We note the significant improvement in the beam shapes compared to the element beams. The same colour scales have been used in the two figures. This makes it easy to see that the sidelobe level in the optimised CB is much lower than that of the element beams.