Pcb calculator differential pair impedance values

I apologize if this post is in the wrong category, I couldn’t select one matching the issue I am seeing.

I believe this is a bug report.

When calculating differential stripline impedance using the built-in PCB Calculator from KiCad 5.1.4, I always get results that differ from other such calculators (for instance Saturn PCB Design or this: https://www.everythingrf.com/rf-calculators/differential-microstrip-impedance-calculator )

I have tried fiddling with all available parameters to see that would affect the results but to no avail.
I have had this experience since version 4.0.7 when I started using KiCad, as a consequence I am not using KiCad PCB calculator at all.

I believe this other post is describing the same thing as I am seeing: https://forum.kicad.info/t/how-to-calculate-differential-pair-widths-spaces-for-ethernet/2959

EDIT:
Okay, I found one thing that was confusing: In the section Substrate parameters the field designated T is not at all related to the substrate but rather the Physical Parameters. After setting this to some sane value like 35 um the output of the calculator has started to make sense and I have no more problems to report.

However I would suggest the T-parameter be moved to the Physical Parameters section and possibly also the H-parameter, as these are the values that I believe one will be most likely to adjust.

This topic was automatically closed 90 days after the last reply. New replies are no longer allowed.