Characteristic Impedance mismatch with Keysight ADS calculator
I suspect it has to do with correction for metal thickness. I'm curious about what ADS would say with a thin metal, say 0.1 mil. That said I'm going to close this bug and refer to the current tracker on github where I do have an open issue on this topic (coplanar waveguide and thick metal). If you don't mind, please add any updates there (trying to keep consolidated in one spot). In the mean time I'd go with the ADS result. https://github.com/dmcmahill/wcalc/issues/16
The "Tmet" parameter is ignored for coupled microstrips
https://github.com/dmcmahill/wcalc/pull/22 has added some correction for Tmet. I also think it remains to be fully verified. I was looking at the original references and also at what transcalc did. I think they may have a factor of 2 bug in one of their equations for the correction (one of the references uses space between traces as "2s" as opposed to just "s"). Unfortunately the primary reference for coupled microstrip does not give full details on how the thickness correction should be applied....
Comparing Microstrip and Coplanar Waveguide calculations
closing here and moving to https://github.com/dmcmahill/wcalc/issues/19
My apologies for the very very slow response. I've moved development over to github, https://github.com/dmcmahill/wcalc and am going through all the bugs over here on sf to address them before turning off the sf trackers. I've copied this to issue https://github.com/dmcmahill/wcalc/issues/19 and will have some more to add to the issue shortly.
Marking as closed, will continue at https://github.com/dmcmahill/wcalc/issues/16