UPLINK FREQUENCY:

• The communication between earth station transmitter towards satellite is known as uplink frequency.
• Uplink of satellite is the frequency at which the earth station is transmitting the signal and satellite receiving it.
• Uplink frequency range = 5.9 GHz to 6.4GHz

DOWNLINK FREQUENCY:

• The communication between satellite towards earth station receiver is known as downlink frequency.
• Downlink frequency of satellite is the frequency at which the satellite is transmitting the signal and earth station receiving it.
• Downlink frequency range = 3.7 GHz to 4.2 GHz.

Reasons:

1. Same antenna is used for transmission & reception.
2. The uplink and downlink bands are separated in frequency to prevent oscillations within the satellite amplifier while simultaneously transmission and reception.
3. Moreover low frequency band is used on the downlink to exploit the lower atmospheric losses thereby minimizing satellite power amplifier requirements.