Question

A lossless transmission line is terminated with a load which reflects a part of the incident power. The measured VSWR is 2. The percentage of the power that is reflected back is 

 (A) 57.73 

(B) 33.33 

 (C) 0.11 

(D) 11.11 

Answer 1

Correct option (D) 11.11

Explanation:

VSWR = 2 

Reflection coefficient is given by,

|Γ| = (s - 1)/(s + 1) = (2 - 1)/(2 + 1) = 1/3

 The ratio of reflected power to incident power is given by,

P_r/P_i = |Γ|²

where, Γ = reflection coefficient at load

P_r/P_i = (1/3)² = 1/9 = 0.11

In percentage, P_r/P_i = 11.11%