figure is a one of main performance parameter for HAM VHF/UHF/SHF
systems. A low noise figure provides improved signal/noise
ratio (SNR) for our EME/MS setup. If you want to try make
good low-noise amplifier (LNA) - you must improve noise
figure measurement accuracy. Is this easy work ? But we
can do it !
I use the Y-factor
method with different noise source : Home made source
(p-n channel or diode), industrial noise source, "cold"
TRX system = THOT(1/(Y-1))
Fixing Measurement Errors
1. Use big difference between
. ENR must be more than 10-15
2. Use attenuator 10-20 db
between source and LNA, because that S11 of source or
LNA not optimal (SWR=1)
3. Use broadband IF section
before the detector, but use IF section with Quality Band
Pass Filter (BPF).
4. IF section must have good
perfomance IP1 , IP3
5. Detector must have stability
and accuracy more than 0,05-0,1 db in band 20-25 db
You can download
NF calculator - NoiseFigure_v4.xls
Meter for measurment
Noise of Moon and Sun
Noise Meter uses
Log.Detector AD8307 , ADC by MCU ATmega16, Precision voltage
regulator LM4040A, thermometer DS18D20 in noise source
horn for measurement Noise factor of LNA on 5,7 Ghz and 10 Ghz
NF my 1296 MHz system
Look here my
new idea ! Noise tester for test HF-VHF transceivers.
You need only
connect 9V battery to Noise Tester in PL-259 connector and you
see in S-metr S 6-7 from 160 to 2 meters !