Design and development of south-facing Ka‑Receive band 260 mm shaped-beam reflector antenna for communication spacecraft

This paper reports design and realisation of a ϕ260 mm shaped-beam reflector antenna for geostationary Earth orbit (GEO) communication satellite. It is intended to receive signals from low Earth orbit (LEO) satellites at Ka-band. Due to limited available space on the earth viewing (EV)-deck, the antenna is mounted on a raised platform, which is supported by the tower of another antenna. Due to nearby structure, the envelope of the antenna was constrained to 260 mm (E-W direction) × 400 mm (N-S direction) × 350 mm (H). Further, to accommodate the antenna with minimum scattering, the antenna has been rotated to face towards south direction. We have devised and developed a shaped reflector in a rotating condition (−90° in yaw) to keep reflector towards south‑facing. Its surface was shaped to get contoured beam. Minimum radius of curvature (RoC) is also controlled during surface shaping to meet fabrication requirement. The complete antenna has been analysed using method of moments (MoM) technique, accounting impact of horn and mast structures. Higher edge of coverage (EoC) gain and good cross-polar discrimination (XPD) have achieved under the constrained volume of the antenna and in a scattering environment. The antenna is designed to meet EoC gain (>24 dBi), (<−18.8 dB) and circular polarisation at 26.05–26.09 GHz, over a wide coverage. It has been also demonstrated that a shaped reflector antenna provides better performance compared with a reflectarray of identical geometry.