Electronics and Communication Engineering - Microwave Communication - Discussion

2. 

A loss less line of characteristic impedance Z0 is terminated in pure reactance of -jZ0 value. VSWR is

[A]. 10
[B]. 2
[C]. 1
[D]. infinity

Answer: Option D

Explanation:

A pure reactance does not absorb any power.

Therefore VSWR is infinite because |rv| = 1.


Faizz said: (May 25, 2016)  
Can I get some information about VSWR?

Gurpreet Kaur said: (Jun 7, 2016)  
@Faizz.

VSWR means Voltage Standing Wave Ratio = (1 + |rho v|) / (1 - |rho v|).

Here (rho v) is (reflected power)/(incident power).

SWETHA said: (Sep 27, 2016)  
VSWR = (1 + rho)/(1 - rho),
rho = (ZL - Z0)/(ZL + Z0).

SWETHA said: (Sep 27, 2016)  
VSWR = (1 + rho)/(1 - rho),
rho = (ZL - Z0)/(ZL + Z0).

Vinay said: (Dec 3, 2016)  
How? Explain it in clear.

Guru said: (Dec 6, 2016)  
What's that RHO?

Roli said: (Apr 14, 2017)  
Reflection coefficient is ρ.

Vineet said: (Apr 3, 2018)  
In that expression of VSWR, it is the magnitude of reflection coefficient |ρ|.

Beulah Durairaj said: (Aug 7, 2021)  
VSWR = 1 + |ρ| / 1 - |ρ|.

Given: Zo, reactance value = -jZo..
That is ZL = 0 + (-jZo) = -jZo..
ρ= ( ZL - Zo) / ( ZL + Zo)
ρ = -jZo - Zo / -jZo + Zo.

Then take magnitude for ρ.

| ρ | = √ {(-jZo)2 + ( -Zo)2 }/(-jZo)2 + (Zo)2 }
| ρ | = √ { ( Zo)2 + (Zo)2 }/{ (Zo)2 + ( Zo)2 }
| ρ | = √(2 Zo)2/( 2Zo)2
| ρ | = √1 = 1.


VSWR = 1 + | ρ | / 1 - | ρ|
VSWR = ( 1 + 1) / (1 - 1)
VSWR = 2 / 0 = INFINITY.

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