Accuracy of TDR vs TDR/TDT for PCB Trace and Dielectric Characterization

Which measurement method is more accurate for characterizing pcb traces/dielectrics, TDR only or TDR/TDT?

I recieved an email response to your question from "Dr. Marina Y. Koledintseva":http://www.eeweb.com/spotlight/interview-with-dr.-marina-koledintseva she said:

bq). TDR/TDT means “time-domain reflection and time-domain transmission” method. From my point of view, measuring both transmission and reflection coefficient on the lines excited by pulses, gives more information that just reflection coefficient, and thus should result in more accurate measurements.

She also gave this reference:

"S-parameter Measurements with a High-Speed TDR and TDT System":http://www.tek.com/products/oscilloscopes/sampling/interconnect_analysis/customer_papers/sparm_schoen.pdf

Dr.Koledintseva, thank you for the remarks and reference. I'll attempt this later in the week. My intent is find alternative methods of characterizing a near field probe that can be correlated with another method, such as S21 of a VNA. Again, thank you.