Noise Figure Y factor method calculator


This calculator implements the method of Agilent application notes AN 57-1 and AN 57-2 for noise figure measurement, with the addition of an adjustable attenuator after the noise source and between the DUT and instrument. This web page is not a tutorial on noise figure measurement, the above two applications notes do such a good job that I wouldn't try to improve on them. The terminology on this page is largely consistent with that in the applications notes.

Fig 1: Noise Figure measurement using a two stage system.

The terms used in the calculator are as per Fig 1. 

Data entry

Noise measurements may be entered depending on your selection of "Noise Off/On" units on the input form, (consistently) in:

  • dBs;
  • Watts (or proportional to Watts by a constant, eg all input in mW); or
  • Volts  (or proportional to Volts by a constant, eg all input in mV)

Enter only a number in decimal format, no units.

The measurements in the second stage must be wrt the same reference as used in the first stage for correct results. The calculator will stop processing if it detects conditions that would not occur in practice (eg negative Te).

Input form

Noise Off/On units Ambient
temperature (K)
Noise Source:
Cold temperature
Instrument calibration (CAL):
Att12 (dB) Att22 (dB)
Noise Off  Noise On 
Measurement (DUT):
Att112 (dB) Att212 (dB)
Noise Off  Noise On 



If you're clever, you will have worked out you can download this page to your hard disk. If you're smart, you won't, you will run it from the web site and automatically take advantage of any updates.

Other VK1OD tools.


© Copyright: Owen Duffy 1995, 2017. All rights reserved. Disclaimer.