Question

The velocity of propagation on a certain loss-less transmission line is $V=250m/\mu S$. If C=30pF/m and the line is terminated by $50\Omega$ resistors, then the reflection co-efficient is

• A. 0.55
• B. 0.454
• C. 0.5
• D. -0.454

Answer 1

The correct option is D -0.454

$v=\frac{1}{\sqrt{LC}}$
$L=\frac{1}{v^{2}C}=\frac{1}{{(251\times {10}^6)}^2\times 30\times {10}^{-12}}$

$L=5.33\times {10}^{-7}H/m$

$Z_0=\sqrt{\frac{L}{C}}=\sqrt{\frac{5.33\times {10}^{-7}}{30\times {10}^{-12}}}=133.3\Omega$

${\Gamma }_L=\frac{Z_L-Z_0}{Z_L+Z_0}=\frac{50-133.33}{50+133.33}=-0.454$