Satellite television antennas use parabolic reflector or "dish" antennas.They are also incorporate with LNB (Low Noise Block) converter.
The satellite transmits signals at frequencies between 12.2 and 12.7 GHz. Signals at these frequencies would be very quickly attenuated by any coaxial feeder that was used. As feeder lengths may run into several metres or more in many installations, this would mean that the signals that reached the television would be very weak. To overcome this problem the LNB is installed at the feed point of the antenna. Its job is to fold two functions. It amplifies the signal, but more importantly it converts it down to a frequency (usually 950 to 1450MHz) where the loss introduced by the coaxial feeder is considerably less. The amplification provided by the LNB also enables the loss introduced by the cable to be less critical. By performing these two functions it means that domestic coaxial cable can be used satisfactorily, while maintaining sufficiently high signal levels at the receiver.