How do you connect virtual Network anaylzer in a two-port network in Multisim

[Dessy]

Hi everyone. 

I'm currently designing an ADSL transmission in the Multisim environment, my problem is how to connect the network analyzer to the line so I can measure the return loss, insertion loss and other parameters.

Please I'd be very grateful if somebody can help me out as I'm having a big problem figuring out how to establish proper connection of the network analyzer

I have attached a single line unit just to show what Im doing.

Thank you in advance

Dessy

[TrottM]

Hey Dessy and welcome to the forums

When looking to take any sort of measurement it is important to think what is it that I am measuring? it almost always boils down to a voltage, current or resistance.

the network analyzer takes measurement of the S,H,Y and Z parameters of your simulation. Are you aware of what this actually means? that would be where to start. in regards to getting the return loss insertion loss and other parameters you need to know what this means as well.

when you understand what it is you are measuring then I think we would be able to help you more.

[Dessy]

Hi, thank you for your response.

Yes I do undertand what those parameters I'm measuring are, but my only problem is just how to connect the network analyzer to the circuit, I have tried getting help from a few lab technician but none of them seem to have proper knowledge about how to connect it to the line as they are not into RF systems.

I've been told to link the P1 connection to the start of the line, and P2 to the end of the line, but this don't seem to work

Please help out

Thank you

[TrottM]

Hey Dessy

What are the values you are reading then? this should be the correct method of wireing up.

If I remember my theory knowledge correctly S12 is the transmission loss or gain

To measure reflection loss you need to use a directional couplet and wire the analyzer to that and the output of your line. This would then be the S11 measurement.

The return values may or may not have been scaled into decibels I am unsure as to how the data is displayed off the top of my head.

If not then the mathematical function to swap them out is S11=20log(g) where g is the voltage value. It is the same formula for S12 as well.

[Dessy]

Hi Mathew thank you for information, 

I think it'll be better if i attach the circuit layout so you can see what I mean, you are absolutely right about the measurements of the parameters. BUT my problem is to actually connect the Network analyzer properly to the right point on the circuit....because few people ive got in contact with give me different ways of connection, and this frustratingly, gives me different values for the parameters.

So if you can look at the circuit and help me out on how/where the Network analyzer should be connected I'll be grateful

Thank you so much 

Dessy 

[TrottM · Accepted solution]

For getting a propper S12 value this is correct. for S11 you need to use a directional coupler as I mentioned before. this is then wired to the analyzer and you would need to put a load on one end of your network as well.

[Dessy]

Thank You ever so much!

I appreciate that.

[TrottM]

Glad I could help