In order to get the best power transfer from a source to a load, the source impedance must equal the complex conjugate of the load impedance: \(Z\) (impedance, complex number, in ohms), here are 2 examples of Z:.
#SMITH CHART FOR DUMMIES HOW TO#
It will massively improve your RF skills if you are able to take time to learn how to use this chart. Smith chart is really just a plot of complex reflection coefficient overlaid with a normalized characteristic impedance (1 ohm) and/or admittance (1 mho or siemen) grid.Īlthough calculators and computers can now easily give answers to the problems the Smith chart was designed to solve, this great chart still remains a valuable tool. Smith chart was invented by Phillip Smith in 1939 as a graph-based method of simplifying the complex math used to describe the characteristics of RF/microwave components, and solve a variety of RF problems. What is Smith chart and how does it work?
Then, we’ll show them out on Smith Chart and learn how to easily use this great chart to help you resolve those difficult RF impedance matching issues. We’ll briefly mention those basic equations that construct the Smith chart. You’ll not learn the mysteries of the Smith Chart, or those sophisticated formula and special usages of this great chart here.įirstly, you’ll learn these basic parameters such as \(Z\) (impedance), \(z\) (normalized impedance), \(Y\) (admittance), \(y\) (normalized admittance), \(R\) (real part of impedance), \(X\) (imaginary part of impedance), \(r\) (real part of normalized impedance), \(x\) (imaginary part of normalized impedance), \(G\) (real part of admittance), \(B\) (imaginary part of admittance), \(g\) (real part of normalized admittance), \(b\) (imaginary part of normalized admittance), \(Γ\) (reflection coefficient), \(VSWR\) (voltage standing wave reflection), etc.
We’ll discuss the Smith Chart in this sequence and start with the very basic knowledge of this important tool that all RF people should learn and use. Insofar as it is possible, assume that care has been taken to reduce these factors to a minimum, and that, none-the-less, any such measurement will be accompanied by some percentage of error.Impedance Matching and the Smith Chart: The Fundamentals I understand there are many factors that will affect the accuracy of such a measurement. In the case of an inductor which the manufacturer lists as 100 uH at 100 kHz, looking at the S11 plot, at the point where the frequency is 100 kHz, should the X, in R + jX be the same as the (nominal) inductance of the inductor? They will (or should) also tell you the frequency at which this value was obtained, since inductance of anything is not constant over a range of frequencies. At any particular point along the S11 Curve, the Smith chart will display R + jX of the component at a particular frequency.įor commercially produced inductors, manufacturers list a nominal inductance figure, e.g. Impedance is R + jX, where X represents the reactance (inductance/capacitance) of the component. capacitor, inductor, resistor) on a Smith Chart, you will get a curve that represents the impedance of that component as it changes with frequency. If you were to plot S11 of a basic electronic component (e.g.
#SMITH CHART FOR DUMMIES FREE#
If that is the case, please feel free to say so. I realize that such an answer may not be available. (No, you can't use me for testing your newly designed electric chair.) What I need is a simple, direct answer, to a very narrow question. I am not just an electrical engineering noobie, I'm an electrical engineering dummy.
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