L 2.10 -- Smith Charts

Questions of the Day:

• Using a Smith Chart, How do you plot/find:
  • –Reflection Coefficient (Real/Imaginary or Polar Form)
  • –Transmission Coefficient
  • –Impedance (ZL, Zin, etc.) 
  • –Rotating / moving distances towards generator or load
  • –Admittance (YL, Yin, etc.)
  • –VSWR (S) (linear or dB)
  • –lmin, lmax

Reference Material:

• Textbook chapter 2-10
• Smith Chart for you to use:  SMITH.GIF Download SMITH.GIF   ORsmithchart.pdf Download smithchart.pdf
  OR  Two Smith_Charts per page.pdf Download Two Smith_Charts per page.pdf
• The Smith Chart Home Page Links to an external site. (additional tutorials, free computer smith chart programs, reference, and support materials)

Lecture Videos: (Watch these video lectures before coming to class):

• Power point to take notes on: L12 smith charts.ppt Download L12 smith charts.ppt
• Lecture Notes: L13.pdf Download L13.pdf
   
• Handouts:  handouts.pdf Download   handouts.pdf

Applications:

Measurement: Impedance of electromagnetic devices is often measured using network analyzers, which show both the magnitude and phase of this impedance as a function of frequency.  Smith charts are one way of displaying this data.  Check out this tutorial on network analyzers Links to an external site., page 16, to see more.  For the frequencies where the yellow line below is near the outside of the Smith chart, we know it has a high impedance.  At the center, it would be well matched.   The little loop in the center would be typical of a resonant structure, like an antenna.  You try to design the antenna so the tip of the loop is as close to the center of the Smith chart as you can, at the frequency where you want to use the antenna. 

Calculation: Smith charts allow microwave engineers to add or subtract impedances, compute the effect of length or phase shift, amplify or attenuate signals, and convert from impedance (Z) to admittance (Y), among other things.  They are often used to design RF/microwave circuits, impedance matching systems, etc.

The Math behind the Smith Chart (and other good Wikipedia Links to an external site. notes)

Exam Prep: Example Exam question on Smith Charts.pdf Download Example Exam question on Smith Charts.pdf

And Just for Fun ..................................

Smith Chart Art Escher's Art, SC & Hyperbolic Geometry.pdf Download Escher's Art, SC & Hyperbolic Geometry.pdf

Smith Chart Jewelry (by http://www.etsy.com/shop/bongobeads Links to an external site.)

Dr. Furse's Smith Chart Quilt (come visit during office hours and see it)