General question about LNBs

[26YANKEE]

I spent 4 years in the Army as a Satellite equipment repair technician. Back in those days we used a LNA, which was a cryogenically cooled low noise parametric amplifier up in the antenna equipment room, then the signal was sent down to the main building to a down converter, and so on.

Now, I understand that an LNB is a Block...including the LNA and the downconverter, but what I don't understand is how is the low noise figure is achieved in the LNB without the cryogenic cooling.

Can anyone provide more detail on that?

 

[berck]

Wikipedia is a good source...

The "low-noise" part means that special electronic engineering techniques are used, that the amplification and mixing takes place before cable attenuation and that the block is free of additional electronics like a power supply or a digital receiver. This all leads to a signal which has less noise (unwanted signals) on the output than would be possible with less stringent engineering.

I suspect the LNA's used in the Army are for detecting very weak signal and hence, are much more powerful than those in the LNB.