Give reason of the following:
(i) For ground wave transmission, size of antenna \(\iota \) should be comparable to wavelength \(\lambda \) of the signal, i.e. \(l=\frac { \lambda }{ 4 } \).
(ii) Audio signals, converted into an electromagnetic wave, are not directly transmitted.
(iii)The amplitude of a modulating signal is kept less than the amplitude of a carrier wave.

A 50 MHz sky wave takes 4.04 ms to reach a receiver via retransmission from a satellite 600 km above the earth's surface. Assuming retransmission time by satellite negligible, find the distance between source and receiver.If communication between the two was to be done by Line of Sight(LOS) method, what should size and placement of receiving and transmitting antennas be?

If the whole earth is to be connected by LOS communication using space waves (no restriction of antenna size or tower height), what is the minimum number of antenna requires? Calculate the tower height of these antennae in terms of the earth's

What is space wave propagation? Give two examples of communication system which uses the space wave mode.A TV tower is 80 m tall.Calculate the maximum distance upto which the signals transmitted from the tower can be received.

Figure shows a communication system. Which is the output power when input signal is 1.01 mW? (Gain in dB=\(10\log { _{ 10 }\frac { { P }_{ 0 } }{ { P }_{ 1 } } } \))