Correct Answer - Option 2 : ∞
Concept:
Voltage standing wave ratio (VSWR) is mathematically defined as:
Γ = Reflection coefficient given by:
\(Γ_L= \frac{{{Z_L} - {Z_o}}}{{{Z_L} + {Z_o}}}\)
ZL = Load Impedance
Z0 = Characteristic impedance
Application:
Given: Zo = 50 Ω and ZL = j50 Ω
Reflection co-efficient will be:
\(Γ_L= \frac{{{Z_L} - {Z_o}}}{{{Z_L} + {Z_o}}}\)
\(Γ_L= \frac{{j50 - 50}}{{j50 + 50}}=\frac{j-1}{j+1}\)
|ΓL| = 1
Now, the voltage standing wave ratio will be:
\(VSWR = \frac{{1 +1}}{{1 - 1}}\)
VSWR = ∞