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Pinging Joel - something to amuze you.  / How would I measure the dynamic range of a VNA?

Question asked by drkirkby on Jun 12, 2019
Latest reply on Oct 2, 2019 by daras

I've splashed out recently on a new 2-port VNA. My budget would not quite stretch to a PNA-X, so had to make do with a NanoVNA which costs £50.99 (less than $65 USD) - luckily that included shipping!  I don't have it yet, but reports have it the menu structure is very much like a 8753. I thought that might amuse Joel if he reads this! 

 

Given a PNA-X is going to be about 35 dB more expensive, I guess one has to make do with the reduced dynamic range of

 

70 dB (50 kHz to 300 MHz)

50 dB (100 MHz to 600 MHz)

40 dB (600 MHz to 900 MHz)

 

I guess one could argue a PNA-X is better value, as the difference in dynamic range exceeds the difference in price!

 

How would one go about measuring those dynamic range figures? With access to a decent VNA, an attenuator can be measured easily. I assume one needs to then measure the difference between the signal and the noise. Is there any standard way of doing this? To measure a 70 dB dynamic range, would one put an attenuator (~ 50 dB ???) on port 2, then switch port 1 between the attenuator and a 50 ohm load? Is there any standard for determining the noise level? It measures at 101 points - I wonder what that number comes from?

 

Dave

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