Question

A transmission line has a characteristic impedance of 50 $\Omega$ and a resistance of 0.1 $\Omega$/m. If the line is distortionless, the attenuation constant (in Np/m) is

• A. 0.014
• B. 500
• C. 5
• D. 0.002

Answer 1

The correct option is D 0.002

Ans : (d)

For distortionless transmission line,

LG = RC

$\Rightarrow \frac{L}{C}=\frac{R}{G}$

Characteristic impedance,

$Z_0=\sqrt{\frac{L}{C}}=\sqrt{\frac{R}{G}}$

Attenuation constant,

$\alpha =\sqrt{RG}=\sqrt{R}\cdot \frac{\sqrt{R}}{Z_0}=\frac{R}{Z_0}=\frac{0.1}{50}$

= 0.002 Np/m