Satellite TV Dish Antenna

For the reception of Direct Broadcast Satellite (DBS) home service, you need a small satellite TV dish antenna. Here, as "small" is considered anything bellow 40" in diameter. Dish antenna mounted at the subscriber's residence receives the signal emitted by a TV satellite.  From the dish, the signal is transferred to the satellite TV receiver and, finally, to the TV set.

DBS dish antenna is of so called "center feed" type, with a paraboloidal dish surface focusing radio waves from TV satellite onto the actual small antenna ( or feed) centered in front it. The assembly containing the feed is called feedhorn. Signal generated by the antenna is fed to the LNB unit.

LNB stands for "low-noise block down-converter". It converts very high satellite signal frequency from the GHz (Giga-Hertz, billions cycles per second) range, or block, into MHz (Mega-Hertz, millions cycles per second) range. Sometimes the LNBF designation is used, which is merely a feedhorn with integrated LNB unit. The LNB also amplifies very weak satellite signal before it makes it to the satellite TV receiver. It is very important that the LNB unit contributes as little as possible of its own "noise" to the signal it amplifies.

The noise produced by LNB is due to its operational temperature, creating thermal radiation effectively lowering the strength of received signal. LNB units have gone long way since the early days: today's LNB noise level standard is around 1dB (decibel), or less. The lower LNB noise level, the lower signal loss due to thermal waves interference, and the better signal quality.

Originally, DBS satellite dishes had a single LNB unit, thus limited to handling a single satellite input. Nowadays, they come with up to 5 LNB units mounted on so called "multi-satellite" dishes. A dual-feed LNB unit has its potential channel capacity doubled, due to being handling both polarization modes (polarization is splitting one same frequency in two modes, so that each mode can be independently used for transmission). It is not to be confused with "dual band" LNB, capable of transmitting two different frequency ranges.