TA0321

2 Polarization selection

3/12

2

Polarization selection

Polarization is a way to give a specific direction to a transmission signal. It increases the beam

concentration.

The signal transmitted by satellite can be polarized in one of four different ways: Linear

(horizontal or vertical) or Circular (right-hand or left-hand).

Consequently, the satellite can broadcast both H and V or LH and RH polarized signals on one

frequency.

Figure 2.

The four different ways of polarization

The “universal” LNB switches the polarization by looking at the voltage that it receives from the

receiver.

Generally, only two signals 13 V and 18 V are used with one type of antenna.

Also, 1 V can be added from a receiver to any of above voltages to compensate for the voltage

drop in the coaxial cable.

1.

actually from 11.5 to 14V

2.

actually from 15.5 to 21V

RHCP

LHCP

HP

VP

RHCP

LHCP

HP

VP

Right hand circular

Left hand circular

Horizontal

Vertical

Linear

Horizontal

Right hand

Vertical

11.7 GHz

12.2 GHz

12.7 GHz

Left hand

Circular