FAQs from Rohde & Schwarz

Achieve noise level below -100 dBm for S21 measurements


For my application I need a noise level close to -100 dBm. Is there a possibility to archieve that?


Yes - with some restrictions. It works if the frequency is not higher than 1 GHz:
Meas: S21 (not S12!)

  • Frequency Stop up to 1 GHz
  • Ref: -75 dBm
  • RBW: 300 Hz
  • TG Pwr: 0 dBm
  • Att: 0 dBm

Now do a "Full 2 Port High Accuracy Calibration". This is the result:

Full 2 port high accuracy calibration result

The noise level becomes better if the calibration is done with Receiver Att of 10 dB and afterwards changed to 0 dB. Please note that "cal ?" is shown then, because there was change of the measurement settings after calibration:

Better noise level with receiver att of 10 dB