Question

Frequency range used in downlinking in satellite communication is:-
(A) $ 0.896{\text{ }}to{\text{ }}0.901{\text{ }}GHz $
(B) $ 0.420{\text{ }}to{\text{ }}0.890{\text{ }}GHz $
(C) $ 5.925{\text{ }}to{\text{ }}6.425{\text{ }}GHz $
(D) $ 3.7{\text{ }}to{\text{ }}4.2{\text{ }}GHz $

Answer 1

Hint To answer this question, we need to consider the parameters of the body of a satellite, such as its weight, strength etc. Then relate them with the frequency used for the communication purpose.

Complete step by step answer
In satellite communication, two kinds of frequencies are used. The first is the uplink frequency, and the second one is the downlink frequency. These two frequencies are used for the communication between the earth station and the satellite. The uplink frequency is used for sending the signal from the earth station to the satellite, while the downlink frequency is used for sending the signal from the satellite to the earth station.
As the name itself gives the idea, the uplink frequency is higher than the downlink frequency. This is due to the fact that the satellite cannot transmit the signals at higher frequencies as this would require a heavy power transmitter, which the light-weight body of the satellite cannot bear. So, it transmits the signals at a lower frequency, known as the downlink frequency
On the other hand, an earth station stands stationary on the ground. So, it can bear the weight of the high power transmitters, and thereby it can transmit the signals at the high frequency, known as the uplink frequency.
The uplink frequency used for satellite communication is $ 5.925{\text{ }}to{\text{ }}6.425{\text{ }}GHz $ and the downlink frequency is $ 3.7{\text{ }}to{\text{ }}4.2{\text{ }}GHz $ .
Hence, the correct answer is option D.

Note
Satellite communication is widely used in day to day life. All the radio, television, internet etc. communications are carried out using satellite communication. Also, the weather forecasting is done by satellite communication. The satellite in space sends the information about the earth’s atmosphere to the earth stations, which is exploited for forecasting the weather. In military operations, the generation of maps, target monitoring etc are carried out through satellite communication.