# Keysight ADS: export S21 to touchstone (as .s1p) from .s2p file

#### a-helwig

##### Newbie
Hello Experts,

I hope someone can help here. I'm doing simulation with ADS and as a result .s2p file is generated. For another simulation I need only S21 parameter from previous simulation and this needs to be also touchstone file format (.s1p). Any idea how to do this?
I can not find any obvious/simple way in ADS

best regards

#### BigBoss

First, .s1p is a One Port Touchstone Format suffix.. .s2p Two Port so on..
Whichever parameter ( $Sxx$ or $Sxy$ )you're interested in, organize your simulation set-up in according to that..

#### a-helwig

##### Newbie
Thanks, but can You please practicaly explain how to do this?
From the two port file .s2p I need only S21 because this represents Z(f) of the structure for which I need to generate Spice model.
The spice model generator needs .s1p file.
What Do You mean with organize simulation setup?

#### volker@muehlhaus

If you want to connect the 2-port device using a single port, you can use a connection like this:

That result is useful, but different from using the S21 values.

I suspect that your are working on something like this:

Good luck!
Volker

#### BigBoss

Thanks, but can You please practicaly explain how to do this?
From the two port file .s2p I need only S21 because this represents Z(f) of the structure for which I need to generate Spice model.
The spice model generator needs .s1p file.
What Do You mean with organize simulation setup?
I couldn't understand your intention.Draw a simple sketch here to understand..

#### a-helwig

##### Newbie

If you want to connect the 2-port device using a single port, you can use a connection like this:

View attachment 162608

That result is useful, but different from using the S21 values.

I suspect that your are working on something like this:

Good luck!
Volker
Thanks Volker,

I'm simply looking fro possibility to extract only S21 data from .s2p file.
This is how my s2p file is looking at the beginning:

! Created Wed Jul 1 10:37:39 2020
# hz S ma R 50
! 2 Port Network Data from SP1.SP block
! freq magS11 angS11 magS21 angS21 magS12 angS12 magS22 angS22
!
1000 0.97347808 -166.857169 0.227379574 -76.7744724 0.227379574 -76.7744724 0.97347808 -166.857169
11000 0.999436631 -178.783965 0.0212249074 -87.871099 0.0212249074 -87.871099 0.999436631 -178.783965
.....

from this touchstone file I need to to create another touchstone file (in this case .s1p), but with only S21 data (means columns 4 and 5)
I cannot find any simple solution to that

any ideas?
--- Updated ---

I couldn't understand your intention.Draw a simple sketch here to understand..
I'm using SPOutput block to write the simulation data into touchstone file
My simulation is using 2 terminations, this means .s2p-file is generated with S11, S21, S12, S22
From this file (or using another trick) I need to extract only S21 column and also save it in touchstone file (as .s1p-file)
I cannot find simple way to do this

regards

Last edited:

#### volker@muehlhaus

from this touchstone file I need to to create another touchstone file (in this case .s1p), but with only S21 data (means columns 4 and 5)
I cannot find any simple solution to that
I would use a text editor then, to remove the other columns. Textpad supports such "block mode" operations.

#### a-helwig

##### Newbie
Thanks, yes sure I also thought about this, but is there really no option in such a big software like ADS to manipulate touchstone data?
Just wondering...

#### volker@muehlhaus

Thanks, yes sure I also thought about this, but is there really no option in such a big software like ADS to manipulate touchstone data?
Just wondering...
I haven't seen that, unless you want to do "manual" data manipulation using data display equations.

And as mentioned, electrically it doesn't make sense to create to the data that you requested. There is no configuration where that data (cut S21 and drop the others) would represent a physical meaningful entity.

If you want to connect a 2-port in 1-port configuration, e.g. 2-port SMD data in shunt configuration, see my post above.

Best regards
Volker

#### a-helwig

##### Newbie
Thanks Volker,
In this case it make sense, because S21 is not really representing S21 that is known from traditional 2 port network.
This represents in this case (bigger package model with big total number of ports) Z(f) that needs to be determined to be used in Broad Band Spice Generator in ADS.

Nevertheless, I manage now to get the data. I was just wondering if there is any method to accomplish this task inside ADS
Do You have example for me for Data Display Equation that will allow to write only S21 (as S11) into touchstone s1p-file?

I wrote simple Python script to perform this task. It is much faster then using notepad and manually remove columns
See attached

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