1. The length can be determined more easily from a resonance measurement of a shortened line with loose coupling of the open end, I guess. With the S11 measurement, the calibration accuracy affects the result. I don't excatly understand the purpose of the 200 ohm termination for your measurement.
Yes, I agree with you on the 200 Ohms resistor here.
why it should be a shortened line? You mean short the end to measure S parameter? Will a open end better suitable for microstrip line?
2. 1 mm to ??
I mean 1mm round error. For example. 2 cm, it actually value will be 20+- 1mm
3. Depends on the exact layout
Yes, I know. Is there a software I can use to calculate for microstrip line?
thanks a lot
P.S.: This post should be better appended to your similar previous thread, I think.