Insertion Loss & Return Loss [hlp]

[No one]

Hello everyone;
Suppose a two-port network with scattering parameters. Please express Return Loss & Insertion Loss by scattering parameters.

 

[flyhigh]

Hi,

Insertion loss is S21 [dB]
Return Loss(es) are -S11 [dB] and -S22 [dB] (minus sign, they are expressed as positive values)

flyhigh

 

[g579]

Just a small correction.
Insertion loss is -S21 [dB]

 

[flyhigh]

Hi,

yes, of course, S21 comes with minus sign as well.


flyhigh

 

[Element_115]

S21 is the Gain of the two port device! Pout/Pin
If it is a lossy or passsive device the gain will be zero or negative (Insertion Loss).
If it is an active device it should have some gain, making it a Positive S21

S11 is the Input ReturnLoss Looking in to Port 1 Pin(forward)/ Pin(reflected Back)

S22 is the Output Returnloss Looking in to Port 2 P(forward)/ P(reflected Back)

When S11 & S22 are Very Negative (dB) That means that none of the power going
in to the port get reflected out!

 

[enark]

S11 is the Input Return Loss and S22 is the Output Return Loss ONLY if S12=0 !!!