ADInstruments S7200 Operation Manual page 104

AD INSTRUMENTS S7200 TV Signal Analyzer Operation Manual
950~2150MHz
LNA Mixer IF Amplifier IRD
LO
LNB
Figure 5-65 LNA Block Diagram
Satellite signals have two types polarization: circular polarization and linear
polarization. The circular polarization include right-hand circular and left-hand
circular polarizations. The linear polarization include horizontal and vertical
polarizations. Most satellite use the horizontal and vertical polarizations
transmission signals. Because the IRD need receiver different type polarization
satellite signals, the polarization selection and modify function is needed for feed
horn. Now, many new productions combine the LNB and Feedhorn into one
production-LNBF (LNB with Feedhorn).
The LNBF often provide two mutually perpendicular probes in feedhorn different
position. Two mutually perpendicular probe respectively receive horizontal
polarization signal and vertical polarization signal, then couple the signal to
microwave LNA. The IRD use the 13V/18V signal to control two polarization paths
amplifier power on or off.
Satellite C band downlink frequency range from 3.7GHz to 4.2GHz, and the C band
LNB is universal in the world. Because each satellite use different frequency in Ku
band, example some satellites use 11.7~12.2GHz, some satellites use
12.25~12.75GHz, the user receives the Ku band signal should choose right
frequency band LNB according to satellite downlink frequency range.
92