I am new into the RF measurements. I was measuring the S11/S22 (reflection) parameters of an RF attenuator (with different attenuation levels, e.g., 10 dB) via a vector network analyzer from Rhode & Schwarz.
I measured the magnitude of S11/S22 of the attenuator, which was typically below -30 dB. But when I measured the phase response of S11, then my teacher said it is not required. So, my question is, why do we not need phase response of S11/S22? I understand that we seek linear phase response in the useful frequency range of S12/S21 parameters (i.e., constant Group delay).
Additional question: Do we not need it at all for other components as well, e.g., Directional coupler?
If not, then why?
If yes, then why?