Parabolic anten nas can be transmitting or receiving antennas. As receiving antennas, the antenna mirrors focus the received microwaves in a small feedhorn, which is placed at the focal point of the antenna mirror.
The feedhorn is part of the receiving system and transmits the reflected microwaves via waveguides to the LNB converter. Feedhorns are independent receiving units, they often form a unit together with the LNB converter: LNB with feedhorn (LNBF). Downstream of the feedhorn is the orthomode transducer( OMT), which selects the received satellite signals according to their polarization and suppresses unwanted signals from neighboring channels.
The feedhorn and LNB converter are mounted on a boom arm at the focal point of the antenna mirror. The size of the feedhorn depends on the antenna geometry and is determined by the ratio of the focal point (F) to the antenna diameter (D): F/D.