TA0321 Datasheet, PDF (2/12 Pages) STMicroelectronics – TECHNICAL ARTICLE

1 What is a Low Noise Block (LNB)?
1 What is a Low Noise Block (LNB)?
TA0321
An LNB is a low noise block module, placed on the focus of the satellite dish antenna (parabola)
that provides the following functions:
● Down conversion of the incoming signal from GHz range to the 910 MHz - 2150 MHz (for
Europe) range called “first conversion signal”. This conversion allows the signal to be
carried by an inexpensive coaxial cable towards the receiver.
● Signal amplification with good noise figure. The LNB improves the first conversion signal
level through the use of a built-in low noise amplifier.
● Selection of Vertical or Horizontal polarization.
● Selects operating band by switching its internal oscillator from Low band to High band
when the LNB “receives” a 22kHz tone. Specifically, the local oscillator (LO) frequency
changes from 9.75 GHz to 10.6 GHz.
– C Band - LO frequency 9.75 GHz
– Ku Band - LO frequency 10.6 GHz
● Miscellaneous functions based on 22kHz tone PPM encoding, as discussed later in this
paper.
Figure 1. OMNI-LNB architecture
RF Input
Antenna
feed
system
Power supply
and
control
Waveguide ^X
transition
and
Y
Depolarizer
H
LNA and ^RHCP
Polaraization _LHCP
matrix
V
Polarization
switch
LNB
Back-end
IF Output
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