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Reflection coefficient basic doubt

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themaccabee

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Hi

May be this is silly.. ive got a doubt..
I ve got a resistor & capacitor load. (R & C in parallel).
I measured the S11 using a VNA the reflection coefficient reading is something like 0.349, -150 degree.(freq=500MHz)

i'd like to know the effect of this load on forward & reflected waves.
That is i know some part of the forward power will be reflected.. the magnitude of reflected power will be depend upon 0.349 & the reflected waves phase will depend upon -150.My doubt is with the phase..

So will the reflected & forward waves will be 150 degree out of phase??
Thanks
 

So will the reflected & forward waves will be 150 degree out of phase??
QUOTE]
Yes,if s11 has been measured correctly. According to the s11 definition, s11 = +1 (φ = 0) is referring to an open circuit, respectively a reflected in phase with forward wave. s11 = -1 (or φ = 180°) means short cicruit, respectively reflected wave out of phase. The phase beyond +/-90° refers to a z11 real part < 50 ohm. You can visualize the impedance composition and refelction factor in a Smith chart.

I presume, that the device under test is placed correctly in the reference plane, otherwise yo get an additional phase shift, that can be considered either by a user open/short/load calibration with the correct reference plane or a "port extension" (shifting the reference plane by a known cable length).
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