The LNB is located at the focal point (in the nose cone) of the satellite dish antenna and amplifies the very weak received satellite signal approximately 1000 times, then converts the received microwave satellite signal to a lower frequency so that not as much signal will be lost in the coaxial cable between the dish and the receiver.

There are two main types of LNBs. The most popular type is the LNB that is attached to a feedhorn and uses an external servo motor to turn a probe inside of the feedhorn to select the polarity of the desired channel. The other type of LNB is actually called an LNBF, where the LNB and feedhorn are one unit and the polarity is switched when the receiver changes the voltage (either 13 or 18 volts) going to the LNBF at the dish. Depending on what voltage is sent to the LNBF by the receiver, either the horizontal or vertical antenna probe inside the throat of the LNBF will be selected. LNBFs are also used on the smaller DBS satellite systems.

LNBs are rated in degrees Kelvin. The lower the rating, the less noise (snow) will be added by the amplifier of the LNB, and the clearer the picture will normally be. No matter the type of LNB, don't get caught up in all of the numbers. Many people think that a lower temperature LNB will always be better than a higher temperature LNB. This is not necessarily true. A 25° PLL LNB will almost always outperform a 17° consumer (standard grade) LNB.

Also, you cannot make up for poor dish alignment or installation with a better LNB or line amplifier. The dish needs to collect the signal and send it cleanly to the throat of the feedhorn. All the electronics in the world cannot help the picture if you are losing half your signal and sending lots of noise into the feedhorn. Use a good LNB, preferably a PLL LNB - but spend time making sure that the dish is properly aligned first.