Verification of S11 and S21

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evoplus

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Hi,

I would like to verify something. In order to have less power being reflected back, when I measured the between 2 ports, I should have a high insertion loss(S11) which is prefered to be more than -20dB.

Whereas in order to most of the power to flow thru fr 1 port to another port, my conversion loss (S21) should be at ard -8 to -12dB. Are my understandings correct?

Thanks
 

I don’t understand very well what you mean with: “conversion loss (S21) should be at ard -8 to -12dB”?
The terminology for S21 is: Forward transmission coefficient (gain or loss)
The value of S21 depend what are you measure.
-If is during Network Analyzer calibration S21 = 0
-If you measure a passive DUT S21 < 0
-If you measure an active DUT S21 > 0
 

Hi vfone,

What I meant is that if for a two port network for example a waveguide, if I run stimulations using software or doing measurment, I could estimate some results that would give me an idea of the actual results

So for the conversion part, my estimate of the S21 which is also the (forward gain/loss) in this case should be ideally less than 3dB. The return loss (S11) on the other hand should be as high as possible which is more than -20dB?

Hope that I have explained it.

Thanks
 

Ok, so you are talking about a passive component (waveguide).
The ideal waveguide insertion loss shall be closer as possible to 0dB.
For example an in-band S21 = -0.3dB, is something normal for a waveguide.
 

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