Mechanical steering is the most affordable
solution for scanning antennas. The challenge is to balance the
trade-offs between high-gain, low profile and wide beam
steering. We previously showed that for a Transmit-Array (TA)
antenna wide elevation scanning can be achieved by moving the
primary source along a line parallel to the aperture. However,
aberrations build up as the displacement relative to the lens
focus increases, limiting the overall scanning performance. In
this work, a new approach to minimize these aberrations is
presented. The design of the TA usually assumes an incident
spherical wave front. Herein, instead of acting only on the phase
correction of the TA, the feed illumination of the aperture is codesigned to minimize the aberrations for all feed positions. The
adjustment of the feed illumination is achieved by placing a
tailored dielectric lens in front of a standard horn antenna
(primary feed). A 28 dBi TA antenna operating at Ka-band
uplink [29.5, 30GHz] with F/D=0.7 and elevation scanning up to
50 degrees is designed. Full-wave simulations show an effective
reduction of SLL (<-20 dB) when compared with a conventional
spherical illumination (<-12dB).