Hello,

this is probably a trivial question, but I can't find a way to change the horizontal units for a time domain trace. In my case I do a Transform on S11 signal, which gives me the horizontal units in seconds, so far so good. Then a create a new trace in which I use the Equation Editor to normalize the original transformed trace to 100 Ohms, but the resultant trace horizontal axis switches back to Hz. How do I turn it to seconds ?

Thanks!

this is probably a trivial question, but I can't find a way to change the horizontal units for a time domain trace. In my case I do a Transform on S11 signal, which gives me the horizontal units in seconds, so far so good. Then a create a new trace in which I use the Equation Editor to normalize the original transformed trace to 100 Ohms, but the resultant trace horizontal axis switches back to Hz. How do I turn it to seconds ?

Thanks!

thank you for your reply!

Just to clarify: is using the Equation Editor to an already Transformed trace into time domain the same, as using the Equation Editor and Transform at the same time to a trace in the frequency domain ?

eq = Tr1 * (some other stuff)

and time domain transform is currently turned on for Tr1, in the equation, Tr1 refers to the underlying frequency domain complex values that make up Tr1. None of the transforms, gates, or formats that are applied to the Tr1 trace on the screen effect the result of the equation.

I'm applying Transform to two different traces: Tr1 is SDD11 and Tr2 is the Transform of the Tr1. Then I display two new traces:

Tr3, where I apply the Equation Editor to Tr2 [100*(1+Tr2)/(1-Tr2)]

- this trace has the horizontal axis in Hz.

Tr4, where I apply the Equation Editor as well as Transform to Tr1

- this trace has the horizontal axis in ns

but, the traces (impedance profiles) are not the same. Any suggestions ?

Thanks!

## Attachments

Sorry for the confusion, but hopefully with the explanation and the diagram below you can properly setup your measurements.

## Attachments

It's pretty clear that Tr4 is not correct, and tr3 is likely correct.

I'll have to think a bit more about how to get a good impedance trace with a time axis....

You may try using the PLTS Software to analyze the data as one of it's powers is to quickly analyze data in different formats and domains.

Odanzy, I actually did use PLTS to look at the impedance profiles. The general profiles are similar, but the problem I am having with the PNA is that my transforms do NOT start at 100 Ohms. Any ideas/suggestions anyone ? THANKS!

Here are PLTS and PNA plots (PNA x-axis is only to 3ns)

## Attachments

How are you calibrating? Are the same load or line standards used for both ports?

here are the screenshots of using ports 13-24 and 24-13. For calibration I use the ECAL (N4433A) and I go thru the dafault values of the ECAL.

## Attachments

here are the screenshots with the added thru cal. It looks that the results track the ports:

## Attachments