Page 46 - SATELLITE AND RADAR COMMUNICATION SYSTEM

It can be easily understand the operation of Transponder from the block
diagram itself. The function of each block is mentioned below.

 Duplexer is a two-way microwave gate. It receives uplink signal from
the satellite antenna and transmits downlink signal to the satellite
antenna.

 Low Noise Amplifier (LNA) amplifies the weak received signal.
 Carrier Processor performs the frequency down conversion of received

signal (uplink). This block determines the type of transponder.
 Power Amplifier amplifies the power of frequency down converted

signal (down link) to the required level.

2. Antennas

Satellite antennas perform two types of functions. Those are receiving of

signals, which are coming from earth station and transmitting signals to
one or more earth stations based on the requirement. In other words, the

satellite antennas receive uplink signals and transmit downlink signals.
The length of satellite antennas is inversely proportional to the operating

frequency. The operating frequency has to be increased in order to reduce
the length of satellite antennas. Therefore, satellite antennas operate in
the order of GHz frequencies.

The most important parameters that define the performance of an
antenna are antenna gain, antenna beamwidth, bandwidth, polarization,

aperture and Effective isotropic radiated power (EIRP).
The antennas, which are used in satellite are known as satellite

antennas. There are mainly four types of Antennas. They are:
• Wire Antennas

• Horn Antennas Tutorial 2d
• Array Antennas
• Reflector Antennas A satellite system is composed of

a satellite bus subsystem and a

satellite payload subsystem.
Explain the function of a payload

38 system.

Satellite System Elements