File:LNB 1.JPG

English: Cross-section of a low-noise block downconverter, the box on the front of a satellite TV dish that receives the satellite signal collected by the dish, processes it, and sends it via a coaxial cable indoors to a satellite TV receiver that is connected to the TV set. The box has a scalar horn antenna (the funnel with concentric rings, left) which collects the microwave beam and directs it into a waveguide, a short closed metal pipe. Two small metal pins project into the waveguide from the circuit board; these serve as antennas which convert the microwaves to radio frequency alternating currents. On the circuit board (center), these are amplified by a low noise amplifier, then a local oscillator and mixer convert the block of frequencies to a lower block of frequencies, which are output to a jack on the outside of the box (black objects, right) to which a coaxial cable is connected to carry the signal inside the house.