Question

Consider a 300 $\Omega$, quarter-wave long (at 1 GHz) transmission line as shown in the figure. It is connected to a 10 V, 50 $\Omega$ source at one end and is left open circuited at the other end. The magnitude of the voltage at the open circuit end of the line is

• A. 60/7 V
• B. 5 V
• C. 10 V
• D. 60V

Answer 1

The correct option is D 60V

Ans : (c)

The $\lambda /4$ line has $Z_{in}^{\prime }=0as{Z}_L=\infty$

Current $I_{in}$ into the line = $\frac{V}{50}=0.2A$

Using current equation on the line

i(x) = $I_{in}=I_{L}cos\beta x+\frac{j{V}_L}{Z_0}sin\beta x$

with x = $\lambda /4,I_L=0as{Z}_L=\infty$

Open circuit end voltage

$V_L=60V$