1.

If a pure resistance load, when connected to a lossless 75 ohm line, produce a VSWR of 3 on the line, then the load impedance can only be 25 ohms. True/False 

Answer»

On a lossless line of R075Ω with resistance load RL

VSWR = S = 3

S = RL/R0 if RL > R0

= R0/RL if RL < R0

RL = SR0 = 3 x 75Ω

= 225Ω

RL = R0/S if RL < R0

= 75/3 = 25Ω

VSWR = (1 + |Γ|)/(1 - |Γ|), Γ = (RL - R0)/(RL + R0)

for R0 = 75Ω, RL = 25Ω

Γ = (RL - R0)/(RL + R0) = 150/300 = 1/2

|Γ| = 1/2 in either case and S = (1 + 1/2)/(1 - 1/2) = 3

The statement, the load impedance can only be 25Ω is FALSE



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