Mohr CT100B Series - Smith Charts; Example Layer-Peeling Trace

5. Math Functions
Figure 5.10. Example layer-peeling trace (yellow, bottom) versus live TDR trace (white,
top). The layer peeled trace reduces the impedance error in the final cable segment (green
arrows) by ~80%.
5.9. Smith Charts
The Smith chart is a useful graphical tool for plotting reflection coefficients and complex
impedance values and can be used to simplify impedance matching. For a very brief introduction
to Smith charts, see Section 7.14. The CT100B allows the operator to display S-parameter return
loss and cable loss traces on a Smith chart. To create a Smith chart, use the following procedure:
1. Create an S
11
return loss plot using the procedure as described in Section 5.4.
2. With the S
11
trace selected, adjust the cursors to minimum and maximum frequency desired
on the Smith chart.
3. Go to SParam Tools and select the Smith Chart option to toggle the Smith chart display.
4. Use the HORIZONTAL POSITION knob to move the cursor along the complex impedance
curve.
Figures 5.11 - 5.14 show Smith chart representations of an open, short, resistive 50 ohm load, and a
reactive 200 ohm load.
88 CT100B TDR Cable Analyzers Operator’s Manual