By the way....

I worked out your method of Noise Figure measurements of two receivers
at a mathematical way and it seemed right.
I am glad the same statement where made by the professionals under us.
They are a bit "rusty" but we need them !


"bviel" schreef in bericht
...

"Steve Kavanagh" schreef in bericht
om...
"bviel" wrote in message
...

Thanks for the suggestions. I'll have a look at the web references.
Just a couple of notes on things that won't work.

Noise performance of Mar's MMIC's should be noted on datasheets.

Yes, but they never show the range of noise figures, only a typical or
worst case numbers. Of course if the noise figure is very low (PHEMT)
then the variability is pretty small as long as the circuit is done
right.
The noise figure of a MMIC is flat from DC to Ghz, the one I worked with.
Did not test the Mar's.

Terminate receiver with 50 Ohm resistor, measure output and label it
zero dB.

This doesn't work, because the noise is dominated by the receiver
noise, not the resistor thermal noise (unless the receiver is very
very good !).
The method is from JT44 EME software where you can measure noise figures.
The Help with the program should explain everything.
I myself am in the position to measure noise with my scope for a "second"
opinion.
The noise of a high frequency transistor b-e diode should deliver the
right
sort of noise
also called white noise.
Or high frequency diode microwave type.
The transistor has because of his junction noise behavior the most real
white noise,
or general white noise.




73,
Steve VE3SMA