Topic: Antennas and Wave Propagation
In a communication system at 300 MHz, the receiving antenna gain is 8 dBi, the transmitting antenna gain is 10 dBi and the transmitting power level is 25 watts, the distance between the transmitter and the receiver is 1 km, the power received at the receiving antenna port (assuming the propagation medium is loss-less):
- A. 1 mW
- B. 9.97 uW
- C. 99.7 nW
- D. 0.0997 nW
Answer: B. 9.97 uW
Explanation: Given f = 300 MHz, G_r = 8 dBi, G_t = 10 dBi, P_T = 25 watts, d = 1 km. Power Received P_r = P_T * G_t * G_r * (lambda / (4 * pi * d))^2 = 25 x 10^0.8 x 10^1 x (1 / (4 * pi * 1000))^2 = 9.97 x 10^-6 W = 9.97 uW.