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Electrical Engineering QUESTION #2173
Question 1
A half-wave dipole antenna has $R_{rad} = 73\,\Omega$, $R_{loss} = 7\,\Omega$, and directivity $D = 1.64$. Its radiation efficiency and gain are:
  • $\eta = 91.25\%$, $G \approx 1.497\,(1.75\,\text{dBi})$✔️
  • $\eta = 80\%$, $G = 1.31$
  • $\eta = 100\%$, $G = 1.64$
  • $\eta = 50\%$, $G = 0.82$
Correct Answer Explanation
$\eta = \frac{73}{73+7} = 0.9125 = 91.25\%$. $G = \eta \cdot D = 0.9125 \times 1.64 \approx 1.497 \approx 1.75\,\text{dBi}$.