Thread: Insertion Loss & Return Loss [hlp]

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

Hi,

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

flyhigh

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

Hi,

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


flyhigh

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!

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