3.4.1    S11

The  button in Scale/Functions tab and Function->S11 command from main menu or context menu activate SWR and S11 calculation. S11 is the absolute value of the reflection coefficient in the considered part of the circuit. The value of |S11| is calculated after placing the markers (cursors) in the maximum and minimum of the field component envelope line.

The calculation result is displayed in the Markers Pane.

Note that the reflection coefficient measured in this way at the input of the circuit should be equal to the value of S11 calculated by the software in S-Parameters post-processing only in two cases:

·       if only one port takes part in the S-parameters extraction,

·       if more ports take part in the S-parameters extraction, but we have chosen Sk1 at reference planes regime and declared the circuit as nonreciprocal (in the S-Parameters or Processing/Postprocessing dialogues of QW-Editor).

When we calculate S-parameters of  N-port circuit with N>1 and one of the following choices made for post-processing:

·       Sk1 at reference planes for the circuit declared as reciprocal

·       Smn at reference planes

the value of |S11| will be automatically corrected for reflections at imperfect absorbing boundaries. Therefore it will not be equal the value shown by the envelope.