Low Noise Block Downconverter – LNB – also called a low noise block – is a receiving device that is fitted on satellite dish antennas for satellite TV reception.
It collects radio frequency waves beamed by a relevant satellite, on the dish antenna, and converts them into signals to be sent through coaxial cable to the receiver or a set-top box placed indoors of a home.
The set-top box powers the LNB, using the same coaxial cable, which feeds the dish antennas signals into it. It is the front section of a satellite receiver which down converts the block of frequencies to lower block of intermediate frequencies (IF).
The down-conversion of the signals is crucial for it to be carried to the indoor satellite TV receiver-through coaxial cable.
If original satellite signals were to be used straightaway for TV transmission, it would require the use of an expensive waveguide technology which is impractical. And therefore, the use of LNB gains significance.
Further, Intelligent designing techniques and the use of expensive and high-performance components such as HEMTs reduces the noise generated by LNBs which makes it a perfect choice for satellite TV transmission system.
Among the different types of low noise block downconverters, widely used are 1) the Multi-output and 2) Quattro LNBs, for DTH TV systems.
Multi-output LNB’s are a single feed horn with multiple ports for multiple tuners. The Quattro LNB is used for a shared dish antenna system to deliver signals to multiple users. Many models are available from RADITEK Inc. with details on the website.