Question

Power density of the receiving antenna is given by _________

(a) \(P_D=\frac{P_t G_t}{4πd^2}\)

(b) \(P_D=\frac{P_t G_t}{(4πd/λ)^2}\)

(c) \(P_D=\frac{P_t G_t G_r}{(4πd/λ)^2}\)

(d) \(P_D=\frac{P_t G_t}{(4πd)^2}\)

I had been asked this question by my college director while I was bunking the class.

This question is from Radio Wave Propagation in section Radio Wave Propagation of Antennas

Answer 1

The correct answer is (a) \(P_D=\frac{P_t G_t}{4πd^2}\)

To elaborate: Power density is the power per unit area at a distance d from the transmitter and is given by \(P_D=\frac{P_t G_t}{4πd^2}\) where Pt is the transmitter power and Gt is the transmitter antenna gain.

Power received by the antenna is given by \(P_r=\frac{P_t G_t G_r}{(4πd/λ)^2}\)