The feed component in a reflector antenna is itself a VSAT antenna that radiates the signal towards the reflector component of the antenna.

The Feed is composed of the Feed Horn, OMT (Orthomode Transducer), the Transmit Reject Filter (which is either built-in or needs to be added on the receive end of the OMT), Waveguide and Circular Tube, for circular polarization requirements. There are three main polarization positions used for SkyVision Services. (See also Linear Cross-polarization, Linear Co-polarization, and Circular Cross-polarization)

You can also view the placement of the Feed below in the VSAT Installation Manual Components Chapter: