Question

The reflection coefficient of a transmission line having characteristic and load impedances as 50 and 30 ohm respectively is

(a) 1/4

(b) 1/8

(c) 1/2

(d) 3/4

This question was posed to me by my school teacher while I was bunking the class.

Question is taken from Reflection and Transmission Coefficients topic in chapter Transmission Lines of Electromagnetic Theory

Answer 1

Correct answer is (a) 1/4

The explanation: The reflection coefficient of a transmission line is given  by, R = ZL – Zo/ZL + Zo, where ZL and Zo is the load and characteristic impedances respectively. On substituting ZL = 30 and Zo = 50, the reflection coefficient R = 50 – 30/50 + 30 = 20/80 = 1/4.