Question

Direction: Given question consists of two statements, one labeled as the 'Assertion (A)' and the other as 'Reason (R)'. You are to examine these two statements carefully and select the answers to these items using the codes given below.

Assertion (A): The power handling capacity of a receiver antenna could be very low compared to the identical transmitting antenna.

Reason (R): A transmitter antenna has to radiate a large power. The receiver antenna will have to deal only with a very small fraction of the radiated power from the transmitter.

1. Both A and R are individually true and R is the correct explanation of A
2. Both A and R are individually true but R is NOT the correct explanation of A
3. A is true but R is false
4. A is false but R is true

Answer 1

Correct Answer - Option 4 : A is false but R is true

Explanation: 

Since it is given, the antenna is identical at the transmitting and receiving end and the antenna is a reciprocal device (it means the properties of the antenna can’t change as its operating mode changes) So the assertion is wrong.

By Friis equation received power of antenna (Pr) is given by \({P_r} = {P_t}{G_t}{G_r}{\left( {\frac{\lambda }{{4\pi R}}} \right)^2}\)

Where \({\left( {\frac{{4\pi R}}{\lambda }} \right)^2} = \) free space path loss

So when a transmit antenna radiates power, an amount of power lost due to free space path loss. So received power is less than transmit power.

For faithful transmission, we have to radiate a large amount of power by transmitting end so reason R) is correct.