Long-term repeatability of a TDR-based printed wiring board dielectric constant measurement system

A new time-domain-reflectometry-based method has been recently developed that provides accurate determinations of the dielectric constant of printed wiring board dielectrics over the frequency range of 0.1 GHz to 10 GHz. The long-term measurement reproducibility, as well as the short-term measurement repeatability, of that method were investigated and the results are reported here.