Wide-angle steerable reflector antenna with fixed-feed and planar mirror for inter satellite link (ISL)

In this paper, the RF design of a Ka-band fixed-feed steerable reflector antenna has been described for inter satellite link (ISL) application. The antenna is comprised a parabolic main reflector and a flat mirror illuminated by a fixed Ka-band feed system. Main reflector and mirror rotate jointly around the feed axis of the feed coordinate system. Main reflector rotates only around the axis normal to the feed axis. The steering antenna is analysed using physical optics/physical theory of diffraction (PO/PTD) methods of Ticra Tool 25.0 software. We have used minimax and multi-level coordinate search (MCS) algorithms for optimisation. The θ and ø angles of the mirror coordinate system are optimised to compensate the beam squint due to offset geometry. Further, the main reflector rim is optimised to equalise the 3-dB beam width in all the cut planes. We have developed a Matlab code to find the values of rotation-1 and orthogonal rotation-2 from the database generated from the analysis and subsequently interpolation. This steering antenna provides constant gain and good axial ratio over wide-angle steering (±50° in Az and EL) at Ka-band.