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Electronics Engineering QUESTION #11710
Question 1
An RF transmission line has a characteristic impedance of $Z_0 = 50\,\Omega$. A load impedance $Z_L = 25\,\Omega$ is connected. The reflection coefficient $\Gamma$ and VSWR are:
  • $\Gamma = -0.33$, $\text{VSWR} = 2.0$✔️
  • $\Gamma = +0.33$, $\text{VSWR} = 2.0$
  • $\Gamma = -0.50$, $\text{VSWR} = 3.0$
  • $\Gamma = 0$, $\text{VSWR} = 1.0$
Correct Answer Explanation
$\Gamma = \dfrac{Z_L - Z_0}{Z_L + Z_0} = \dfrac{25 - 50}{25 + 50} = \dfrac{-25}{75} = \mathbf{-0.333}$. $\text{VSWR} = \dfrac{1+|\Gamma|}{1-|\Gamma|} = \dfrac{1.333}{0.667} = \mathbf{2.0}$. The negative $\Gamma$ indicates the load is resistive and lower than $Z_0$, causing a phase reversal of the reflected wave.