OK, more questions!
I am getting S2P parameters from a network analyzer using a program called "painless extraction".
I save the S2P file to a computer. I then use genesys to show the frequency response of this file by loading it into a 2 port data file circuit element. I then use some negative line lengths to correct for some reference plane extensions so that a short circuit right at the end of the two network analyzer cables looks like a short circuit on Genesys smith chart of S11 and S22.
Now I use variable in the linear graph pop up box: ifft(S
1,1) to compute and display the impulse response on a linear graph.
I am fairly happy. I can see the magnitude of discontinuities in the processed data of a microstrip unit I am testing. I can hold tuning sticks along the microstrip lines, and see their discontinuity in the genesys processed data.
But one thing that is confusing me is...if I see a discontinuity some time from zero, how do I tell if it is inductive or capacitive? I can plot in genesys ang(ifft(S
1,1)) and the impulse response of an open circuit at the end of a line goes from positive phase before it hits the discontinuity to a negative phase after the discontinuity. Similarly, a short at the end of a line has an impulse response that goes from negative phase before the discontinuity to a positive phase after the discontinuity. So there is some phase information in the ifft function.
But I would understand this a little better if I could post process a STEP function. A step function is simply the integral of an IMPULSE function. But I am a little unclear on how I can get genesys to add an integration, or a multiplication by S,
after the ifft is computed. Any ideas?
Edited by: biff44 on Jun 27, 2012 11:36 AM
