what is LNB’s? How its work?

Answer 1

click here http://en.wikipedia.org/wiki/Low-noise_block_converter
it has all the information you need aboout lnb

Answer 2

LNB = Low Noise Block
Modern satellite transmissions which are received by minidishes are transmitted at very high frequencies, around 12GHz. These frequencies are so high that running them through coax cable would deplete them too much and by the time the signal got from your dish to your receiver, there'd be nothing left! The higher the frequency, the greater the loss of signal in coax cable, and that's multiplied against the length of cable you have. So what's the solution? Well you can't make the satellite transmit at a lower frequency because this would require a bigger satellite dish and those frequencies are too crowded with existing services. Instead, a device is placed at the antenna that converts the satellites signals down in frequency to something fit to transport across the cable. This device takes a block of frequencies and linearly downconverts it to another block of frequencies. In the case of a minidish service in North America i.e. DirecTV, it takes 12.2-12.7GHz in and downconverts it to 950-1450MHz. This device is called a block downconverter. A part of the downconverter is an amplifier. Amplifiers create noise and noise is bad as a high noise floor can bury the signal you're trying to receive. An LNB is optimized to produce as little local noise as possible, hence the name Low Noise Block. It's really more of a Low Noise Block Downconverter with integral antenna and feedhorn, although it is commonly abbreviated as LNBF or even more commonly just LNB.
The downconverter requires power to operate so this is sent up the coax cable from the receiver. Remember how I said that there's an antenna in there too? It's actually etched onto a circuit board on there at the base of the integrated feedhorn , and there's two of them; one for right hand circular polarization, one for left hand circular polarization. Using two opposite polarizations allow the satellite to double their capacity by reusing the same frequencies over between polarizations. How does the LNB know which antenna to use? The receiver tells it by how much voltage it sends to it. One polarization is selected by 13V and the other 18V. The signal coming back into the receiver is separated from the power internally by a bias T and that's pretty much how an LNB works.

Answer 3

What Is Lnb

Answer 4

Low Noise Buffer

It works by magic