Influence of an Extended Stub at Connector Ports on Signal Launches and TRL De-embedding

Characterization of PCBs (Printed Circuit Boards) is usually associated with measurement using a VNA (Vector Network Analyzer) in the frequency-domain or a TDR (Time Domain Reflectometer) in the time-domain. The often used signal launch techniques on PCBs based on the VNA or TDR measurement in the microwave frequency range use SMA or 3.5 mm connectors, in edge-launch or vertical-launch fashions. The signal transition between the launch port and the DUT (Device Under Test) introduces errors in the measurement, which is dominant when compared with a transmission line itself on the PCB as the technologies of PCB manufacturing well developed today. Discontinuities at connector ports depend on the port structures and the dielectric properties of the substrate materials. However, an extended stub at a connector port may significantly influence signal launches, or even corrupt a TRL calibration in a measurement