Question

The ‘space wave’ mode of propagation of EM waves is used for LOS communication as well as for ‘satellite communication’. During satellite communication.

(1) The frequencies used are generally in the radio wave and microwave part of the e.m. spectrum; the satellite usually retransmits the signal at a carrier frequency different from the carrier frequency of its incoming signal. 

(2) The frequencies used are generally in the infrared and microwave part of the e.m. spectrum; the satellite always retransmits the signal at the same carrier frequency as that of the incoming signal.

(3) The frequencies used are generally in the radio and microwave part of the e.m. spectrum; the satellite always transmits the signal at the same carrier frequency as that of the incoming signal.

(4) The frequencies used are generally in the infrared part of the e.m. spectrum; the satellite usually retransmits the signal at a carrier frequency different from the carrier frequency of the incoming signal.

Answer 1

Correct option: (1)

Explanation: 

The frequencies, used in satellite communication, are generally in the radio and microwave parts of the e.m. spectrum. 

The satellite receives the signal, amplified and usually retransmits it at a carrier frequency different from the carrier frequency of the incoming signal. It does so to avoid intermixing of the outgoing signal.