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, right) 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
(left), 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
(left) to which a
coaxial cable is connected to carry the signal inside the house.