Vector Network Analyzer

#109

@Psynosaur should we put your port on a new branch in the master repo?

#110

Good afternoon

You are welcome to.

Kind Regards
Ohan Smit
ZS1SCI

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#111

Hi all.
i believe i did the Scalar Network Analyzer with my limesdr-mini last year.
i have since purchased an RF Bridge

i would like to try the tracking generator that the vna script provides.
does everything look like it is connected correctly?
i have a 15db + 6db attenuators to make a total of 21db attenuation.
on the OSL test (Open/Short/Load) i can do the open and the 50ohm terminator load.
with the “Short” do i just short that connection?

just ordered a 10db attenuator and a couple more cables i needed.
what can i do to “short” the sma connector on the rf bridge DUT?
all i have are 50ohm terminator caps sma.

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#112


my new setup for VNA:
10db attenuator and still have problem with “SHORT”
can someone tell me something i can do while doing the vna test?
do i just use a paperclip?
#113

Never was in position to play with that particular application on Lime
but usually you need something similar to thing on the right…
In your case must be SMA kind of connectors :wink:

Open is nothing within proper connector
Short is short circuit on the end of the similar connector
Load is 50 ohm resistance within similar connector

#114


the short piece of coax is terminated at 0ohms.
i checked it with my Digital Meter.
now i just remove it and hook antenna to it.
hope it works ok

#115

Yes
It should work for demo in case that you have 50 ohm on REF side of that bridge…
(my Eagle bridge have internal REF)

#116



using these commands.
‘python measureVNA_900M.py r75’
‘python calculateVNA_900M.py r75 plot’

is there any reason to use a noise source and the SNA scripts over the VNA scripts?

#117

Calibration shorts are shorted within the plug and using a piece of coax with a short at the end is not going to be the same. It may measure 0 ohms at DC, but this doesn’t mean it will be any good for calibration.

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#118

I think in the examples “docs” pdf they say to use a load and not short.
We should be able to use an Open and Load to do vna and sna

#119


This is an example of what you need.

Ed

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#120

GUI Please…

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#121

I made a SNA code with html/javascript GUI, check out if you interested:

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#122

That looks fantastic, @nepe! Could you drop me a line on myriadrf@halfacree.co.uk? I’d love to ask you a few questions about it with a view to highlighting the project on Lime Micro’s Community hub.

#123

That looks great!!!

#124

Another test, sweep time was 73sec.

#125

Great work Nepe!
Can you add SWR markings?
Can you add progress bar, so we know when the sweep has finished?
Thanks for the effort!
Best Regards,
Kiril

#126

Yes, i can add a SWR measurement mode maybe in next week. Currently working on increasing the sample rate to reduce the sweep time.
The orange line shows the sweep position. See the screenshot above.

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#127

Dear Nepe,
The orange line jumps around the screen all the time and i am not quite sure when to stop the measurement when i am calibrating with the short standard.
It will be nice if it is possible to have a “single sweep” option, so the software will do a single sweep for calibration and then stop.
Thanks again for the great work!
Cheers.
Kiril

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#128

Today i pushed a new version to the GitHub. Added sample rate selection, more visible sweep cursor, SWR display mode, sweep time improvements, modular sweeper, and bug fixes.

With 20MS/s 500KHz resolution(steps=40) a 100MHz sweep only takes about 6sec. I also tried a multi tone measurement method(MultiToneSweeper.py), with the same settings the sweep time is halved but its highly reduced dynamic range so no ui options added for this right now.

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