Design of Spaceborne Multibeam Antenna Feed Assembly with User/Gateway/Tracking Function

In this paper, a dual band and dual circularly polarized feed assembly for very high throughput satellite (VHTS) ka-band multibeam antenna is designed and validated, which can meanwhile form user beam, gateway beam and RF tracking beam. The feed assembly measurement results show that the VSWR is less than 1.12(Tx band:17.7-20.2GHz, Rx band:27-30GHz), the Tx-Rx isolation is better than -55dB@Tx and - 70dB@Rx and the port polarization isolation is less than -18dB. The feed patterns illuminating a reflector antenna meet the taper level requirement at ±15°taper angle. The TE21 mode difference pattern has less than -30dB zero depth, which can support the RF tracking function very well. Finally, the whole antenna measurement patterns also verify the design of the feed assembly.