Question

What does the term ‘LOS communication’ mean ? Name the types of waves that are used for this communication. Give typical examples, with the help of a suitable figure, of communication systems that use space wave mode propagation.

Answer 1

LOS Communication: It means “Line of sight communication”.

Space waves are used for LOS communication. In this communication the space waves (radio or microwaves) travel directly from transmitting antenna to receiving antenna.

Communication System using Space wave mode propagation are

(i) LOS communication and Fig. shows LOS communication system.

If transmitting antenna and receiving antenna have heights hT and hR respectively, then Radio horizon of transmitting antenna,dT = √(2hTRe)

where Re is radius of earth and radio horizon of receiving antenna.

T = √(2hTRe)

∴ Maximum line of sight distance dM = dT +de = √(2hTRe) +√(2hRRe)

(ii) Television, broadcast, microwave links and satellite communication The satellite communication is shown in fig. The space wave used is microwave.