Thanks for all the details, Alan. My program does have group delay, which is differential phase shift. It does extract Q from S11 or S21 when measuring inductance.
I've changed to displaying SWR circles for SWR = 1.5, 2, and 3 simultaneously. I may add another curve for Q contours of 1, 2, and 3. I would leave calculation and interpolation to the user for now.
Any other suggestions for specialized curves or features?
What chart program are you using?
Brian
