Topic: Electronics Engineering
The electric field intensity at a distance of 10 km from an antenna having a directive gain of 10 dB and radiating a total power of 60 kW is
- A. $0.6~V/m$
- B. $1.2~V/m$
- C. $0.36~V/m$
- D. $13.3~\mu W/m^{2}$
Answer: A. $0.6~V/m$
Explanation: $P_{avg}=\frac{G_{d}}{4\pi r^{2}}\cdot P_{rad}$ and $P_{avg}=\frac{E^{2}}{240\pi}$. $E^{2}=\frac{G_{d}\times60}{r^{2}}\cdot P_{rad} = \frac{10\times60}{10^{8}}\times600\times10^{3}$. $E=\frac{3}{5}=0.6~V/m$.