Re: Help: correct use of a spectrum analyzer (interpreting signalpower measurements with various RBWs)

Max65 wrote:

That was in the C-band UPLINK frequency range. Everything goes up
around 6 GHz and is offset by 2 GHz and comes back around 4 GHz.

I know that, we had it in Europe too, but it seems that Dimitris's SA
has a spurious signal generated by itself, because it receives that
signal everywhere at the same level, removing the antenna too!
I take a look to his SA model specs, and discovered that it's a
portable SA intended for EM "pollution" measurements.
You should know that before this last generation of instruments, the
people who made EM "pollution" measurements used for a long time
simple broadband detectors connected to a characterized antenna. They
had to specify the frequency where they made their measurements to
correct the antenna gain, but since they didn't know the complete
enviromental EM spectrum in that moment, they ignored for a long time
that their measurements was wrong and could be in excess of 1000-2000%
due to the received unknown signals.
Narda Microwave produced those instruments and it was the first that
changed the production to selective portable SA, and used the above
consideration for advertize their new product.
One friend of mine lead me one broadband detector one day to check it
with my benchtop SA, and the results were demoralizing.

It's true, the time is changing and electronics teaches us that all
can be made always smaller than yesterday, but when you deal with
microwaves it's very important to take care of good shielding between
the function blocks of your device, expecially when you device is a
measuring instrument.
Have agreat day.
Massimo


I've worked up to KU band on the production floor with dozens of
benches full of operating test equipment. Our products were well
designed in separate shielded modules and lots of semirigid cable. All
it takes is a loose connector, a broken solder joint on a connector, or
a loose shield and you'll have RF radiation or ingression problems.

If the problem is internal, he'll need a better instrument to
troubleshoot his SA.


--
Service to my country? Been there, Done that, and I've got my DD214 to
prove it.
Member of DAV #85.

Michael A. Terrell
Central Florida
.

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