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Quarter wave transformer.

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alphacat

New Member
Hello,

I dont understand why when using a quarter wave transformer, all power is delivered to the load.



I understand well that in point A, Zin(A) equals to Zo, and therefore there's no reflection - Γ(A)=0.
Moreover the quarter-wave lenght line is lossless and therefore it absorbs no power.

But why is the reflection coefficient in point B disregarded?
Zin(B) = RL ≠ √(ZoRL), Therefore some of the power delivered to the load is reflected and retreats towards point A, and back to the generator.

So there's still some power going back to the generator, isnt it?
 

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RCinFLA

Well-Known Member
quarter wave line is used as an impedance matching circuit. Reflection coefficient is not ignored. Look up 'Smith Chart'. Normalize chart to Z1 then plot R1 and rotate it toward source.
 

alphacat

New Member
Hey,

Looking at the smith chart of this circuit,
The left transmission line is represented by a dot in the origin,
and the right transmission line is represented by a circuit, that is derived from the coordinates: (√(RL/Zo), 0) - that is since the normalized Zin(B) equals to √(RL/Zo) + j0
 
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