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Adapter removal using different calibration types

Question asked by jeremy_m on Jun 15, 2006
Latest reply on Jun 16, 2006 by Dr_joel
I have come across an issue while trying to perform an adapter removal calibration.  A passive DUT I need to measure has an SMA(f) connector on one end, and a microstrip line on the other. 
I ended up doing 2 calibrations, one at the SMA plane (OLST), and another to the end of the microstrip (LRL).  I then measured the time delay of the adapter. 
The problem I have run into is that when I have the VNA do the adapter removal, I get some wierd stuff for the phease of s21 & s12.  For instance, i'll get phase wrapping from -120° to +100° instead of +/-180° with some wierd jumps in between.   
Could this problem be due to the fact that the cables from my network analyzer have a different propagation velocity than the part of the microstrip coupon I am trying to remove?