I keep saying that one day I’m going to really master the Smith Chart. I kind of understand them, but don’t ask me to give an impromptu lecture on how they work and what they’re used for. That being the case, I keep collecting links to articles on the net that are supposed to explain how they work. Here’s my latest collection:
How does a Smith Chart work?
The Smith chart appeared in 1939 as a graph-based method of simplifying the complex math (that is, calculations involving variables of the form x + jy) needed to describe the characteristics of microwave components. Although calculators and computers can now make short work of the problems the Smith chart was designed to solve, the Smith chart, like other graphical calculation aids remains a valuable tool.
The Smith chart: more vital after all these years
Using the Smith chart, you can graphically illustrate the complex impedance, Z=R+jX, of a transmission line, antenna, amplifier, or any signal point in the RF range at which the simple resistive approximation is not sufficiently valid. However, the ability to place the real and imaginary parts of Z on a 2-D graph instead of using numbers for R and X is not what makes the Smith chart significant.
Smith Chart: Old tool, new home
Even in these days, when news travels instantly and there are few secrets, it’s possible to miss an important or interesting story. That’s what happened to me recently: I was doing some online research and came across an item from October 2015, published at IEEE Microwave Magazine : “The Smith Chart Comes Home [President’s Column].”
The news was simple: the column explained that IEEE MTT-S [Microwave Theory and Techniques Society] was buying “the rights from the Smith family of the Smith trademark belonging to Analog Instruments, along with the copyright. In return, the MTT-S would make the Smith chart available to students, practitioners, and indeed people all over the world involved in microwave technology.”
Markus Lenggenhager says
To “play” and get familiar with the Smith Chart I recommend SimSmith: http://harriman.ddns.net/Smith_Charts.html
Browse thru the manual and take a look at the excellent YouTube tutorials!
73, Markus HB9BRJ aka AE6MG
Eugene Mah says
Alan Wolke (W2AEW) has a few great videos demonstrating Smith charts on his YouTube channel too (https://www.youtube.com/user/w2aew/). Definitely worth watching. #274-276 and #278
Eugene, AB4UG
Rob W4ZNG says
And I’m going to understand Smith charts too someday… just after I (puts head in hands) … I learn CW.