Topic: Electromagnetics
A lossless transmission line is 80 cm long and operates at a frequency of 600 MHz. The line parameters are $L=0.25~\mu H/m$ and $C=100~pF/m$. Find the phase velocity:
- A. $3\times10^{8}m/s$
- B. $2\times10^{8}m/s$
- C. $4\times10^{8}m/s$
- D. $6\times10^{8}m/s$
Answer: B. $2\times10^{8}m/s$
Explanation: The phase velocity $v_p$ of a lossless transmission line is given by $v_p = \frac{1}{\sqrt{LC}}$.
$v_p = \frac{1}{\sqrt{(0.25 \times 10^{-6}) \times (100 \times 10^{-12})}}$
$v_p = \frac{1}{\sqrt{25 \times 10^{-18}}} = \frac{1}{5 \times 10^{-9}} = 0.2 \times 10^9 = 2 \times 10^8~m/s$.