Smith chart
In my undergraduate EM class, I didn’t particularly pay attention to this part of the course, because it wasn’t on the test. I ended up never knowing what the heck the Smith chart is supposed to be — always thought it was some kind of polar to rectangular complex number conversion chart. Today through random browsing I found this simply excellent explanation:
http://www.maxim-ic.com/appnotes.cfm/an_pk/742/
Turns out it is not quite what I thought, and it is pretty neat. It does convert between two complex numbers, but the relationship has nothing to do with rectangular to polar. It’s the real and imaginary grid lines of normalized load impedance (the circles) layered on top of the real and imaginary grid lines of normalized reflection coefficient (the straight lines). Normalized load impedance and normalized reflection coefficient are functions of each other, so the Smith chart is used to convert between them. Very nice!
