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Noise Source Calibration
Category: EME Equipment, Created: 2005-03-17 22:11:24

I have the priviledge to have a noise figure meter of the latest technology.
Noise Source with ENR of approx. 6dB, fits to  Agilent 8973A Noise Figure meter 10MHz to 3GHz, sweeps NF and GAIN. This precious toy helps to win the EMEers fight against noise...

The ENR of my noise source N4000A is known. The 3 tables below tell you the ENR from 10MHz to 3GHz:

ENR Table SNS 4000A HB9BBD p.1 ENR Table SNS 4000A HB9BBD p.2 ENR Table SNS 4000A HB9BBD p.3

I calibrate my NF meter with the SNS noise source above. The result of this proceedure is that the System NF and Gain values are normalized to 0dB.
I then disconnect my noise source and connect the DUT. The gain values in the plots below, mathematically adjusted with the NF of my noise source from the tables, offer as a result the ENR of the Dut.
if on the plot of the DUT the ENR (gain) is say 0.5dB it is 0.5dB more than my noise source.
Adding the ENR value of my noise source from the tables above to 0.5 gives the ENR of th DUT.

The plotted NF of the noise source is the reciprocal value of the gain. To explain this, imagine a 1dB attenuator in front of a LNA. It creates the NF to increase by 1dB and it reduces the gain by the same value.

Homemade noise sources have very different ENR patterns. It helps a lot to know where the ENR curve (gain) is flat and where on the frequency domain unusable values occur. Here come the patterns of 5 DUT's, which G4DZU sent to me:

OE9PMJ Noise Source 30 50 1000MHz ... OE9PMJ Noise Source 1296 1420 1600 2320 MHz

Noise Source G4DZU ... Noise Source G4DZU 1-3 GHz

ETN (commercial noise source)
ETN NS 30 50 100 1000MHz ... ETN NS 1296 1420 1600 2320

AILTECH Serial nr 1613 (commercial noise source)
Ailtech serial nr 1613 100-500MHz ... Ailtech serial nr 1613 1000-2500MHz

AILTECH Serial nr S-4166 (commercial noise source)
Ailtech serial nr S-4166 100-500MHz ... Ailtech serial nr S-4166 1000-2500MHz

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