1 What is a Low Noise Block (LNB)?

TA0321

2/12

1

What is a Low Noise Block (LNB)?

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

Waveguide

transition

and

Depolarizer

Antenna

feed

system

Power supply

and

control

LNA and

Polaraization

matrix

Polarization

switch

LNB

Back-end

IF Output

H

RHCP

LHCP

V

X

Y

RF Input