Thank you for visiting RF Cafe!

Your RF Cafe
Progenitor & Webmaster

Click here to read about RF CafeView the YouTube RF Cafe Intro VideoKirt Blattenberger
BSEE
KB3UON
EIEIO

Carpe Diem!
(Seize the Day!)

5th MOB:
My USAF radar shop

Airplanes and Rockets:
My personal hobby website

Equine Kingdom:
My daughter Sally's horse riding website

RF Cafe Software

Calculator Workbook
RF Workbench
Smith Chart™ for Visio
Smith Chart™ for Excel
RF & EE Symbols Word
RF Stencils for Visio

Noise Figure  <-->  Noise Temperature Calculator

This JavaScript calculator converts between noise figure and the equivalent noise temperature..

Conversion Between Noise Figure
and Noise Temperature


Noise Temperature (K) = TREF *

Noise Figure (dB) = 10 * log10 RF Cafe - Noise temperature to noise figure conversion equation

Note that unless otherwise specified T
Ref = 290 K

So, just what is noise temperature and why is it used? Simply put, noise temperature is the temperature at which a resistor at the component / system input would generate the same amount of noise measured at the output. It goes back to the familiar kTB calculation for thermal noise power. Noise temperature is often used in calculating the overall noise figure of a system that includes an antenna at the input. That is because strictly speaking, a 1-port device like an antenna cannot be defined in terms of noise figure. If you begin with a system at room temperature (290 K) and add a component at the input that itself has a noise temperature of 290 K, the doubling of noise power increases the overall noise figure by 3 dB (2*290-290=290). A 6 dB increase is a 4x increase in noise power (4*290-290=870). Cascaded noise temperature is done just like with noise figure.

Numerical inputs are not error trapped but are converted to absolute values (no negatives).
Calculated values do not change until the "Calculate" button is clicked.
  Reference Temperature: K    
Noise Figure: dB =
  Noise Temperature: K =

NF(dB) TN (°K)   NF(dB) TN (°K)
0.1 7 2.1 180
0.2 14 2.2 191
0.3 21 2.3 202
0.4 28 2.4 214
0.5 35 2.5 226
0.6 43 2.6 238
0.7 51 2.7 250
0.8 59 2.8 263
0.9 67 2.9 275
1.0 75 3.0 289
1.1 84 3.1 302
1.2 92 3.2 316
1.3 101 3.3 330
1.4 110 3.4 344
1.5 120 3.5 359
1.6 129 3.6 374
1.7 139 3.7 390
1.8 149 3.8 406
1.9 159 3.9 422
2.0 170 4.0 438
RF Cafe - Noise figure equation

Related Pages on RF Cafe
- Noise Figure <--> Noise Temperature Calculator
- Noise Power and Voltage
- Cascaded Noise Figure
- Noise Figure Meters & Noise Generators
- Noise Sources

Copyright 1996 - 2016
Webmaster:  Kirt Blattenberger, BSEE - KB3UON

All trademarks, copyrights, patents, and other rights of ownership to images and text used on the RF Cafe website are hereby acknowledged.