Smith Chart Tutorial

Smith Chart Tutorial
Learn the Smith Chart through interactive flash programs
http://www.fourier-series.com/rf-concepts/smithchart.html

HINT: TRY PUSHING F11 KEY TO GET BIGGER SCREEN IF THE FLASH PROGRAM IS TOO BIG FOR SCREEN!

This Smith Chart Tutorial Consists of 5 Flash programs with embedded audio. These programs will allow you to learn the Smith Chart through interactive flash programs.

Tutorial 1: Basics of the Smith Chart: Impedance, Admittance charts, Reflection Coefficient representation.
Click Here For The Flash Program For Smith Chart Basics
(This is about 11 M file - most of the file space is audio)

Tutorial 2: Use the Smith Chart to Match an arbitrary load using Lumped Capacitor and Inductor components
Click Here : Flash Program For Matching Basics Using A Smith Chart
(This is about 4 M file - most of the file space is audio)

Tutorial 3: Use the Smith Chart to see how transmission line affects the reflection coefficient. Also match an arbitrary load using a transmisison line and a Lumped (Capacitor/Inductor) element.
Click Here : Flash Program Showing How A Transmision Line Works On A Smith Chart
(This is about 3 M file - most of the file space is audio)

Tutorial 4: Learn Basic Stub Tuning:Use the Smith Chart to see to convert a transmission line into Equivelent Capacitors and Inductors.
Click Here: Flash Program Showing How Transmission Line Stubs Can Be Used As Matching Elements
(This is about 2.5 M file - most of the file space is audio)

Tutorial 5: Learn to Convert the Smith Chart results into actual Capacitor and Inductor Values and into actual transmission Line lengths. This shows how to convert the 1ohm Smith chart to a 50 ohm chart and how to get useful real world design results
Click Here: Flash Program That Shows How To Convert Susceptance And Reactance Values Into Actual Inductor And Capacitor Values
(This is about 1.5 M file - most of the file space is audio)


Smith chart
http://en.wikipedia.org/wiki/Smith_chart

The Smith chart, invented by Phillip H. Smith (1905-1987),[1][2] is a graphical aid or nomogram designed for electrical and electronics engineers specializing in radio frequency (RF) engineering to assist in solving problems with transmission lines and matching circuits.[3] Use of the Smith chart utility has grown steadily over the years and it is still widely used today, not only as a problem solving aid, but as a graphical demonstrator of how many RF parameters behave at one or more frequencies, an alternative to using tabular information. The Smith chart can be used to represent many parameters including impedances, admittances, reflection coefficients,  scattering parameters, noise figure circles, constant gain contours and regions for unconditional stability.[4][5] The Smith chart is most frequently used at or within the unity radius region. However, the remainder is still mathematically relevant, being used, for example, in oscillator design and stability analysis.[6

Overview

The Smith chart is plotted on the complex reflection coefficient plane in two dimensions and is scaled in normalised impedance (the most common), normalised admittance or both, using different colours to distinguish between them. These are often known as the Z, Y and YZ Smith charts respectively.[7] Normalised scaling allows the Smith chart to be used for problems involving any characteristic or system impedance which is represented by the center point of the chart. The most commonly used normalization impedance is 50 ohms. Once an answer is obtained through the graphical constructions described below, it is straightforward to convert between normalised impedance (or normalised admittance) and the corresponding unnormalized value by multiplying by the characteristic impedance (admittance). Reflection coefficients can be read directly from the chart as they are unitless parameters.

The Smith chart has circumferential scaling in wavelengths and degrees. The wavelengths scale is used in distributed component problems and represents the distance measured along the transmission line connected between the generator or source and the load to the point under consideration. The degrees scale represents the angle of the voltage reflection coefficient at that point. The Smith chart may also be used for lumped element matching and analysis problems.

Use of the Smith chart and the interpretation of the results obtained using it requires a good understanding of AC circuit theory and transmission line theory, both of which are pre-requisites for RF engineers.

As impedances and admittances change with frequency, problems using the Smith chart can only be solved manually using one frequency at a time, the result being represented by a point. This is often adequate for narrow band applications (typically up to about 5% to 10% bandwidth) but for wider bandwidths it is usually necessary to apply Smith chart techniques at more than one frequency across the operating frequency band. Provided the frequencies are sufficiently close, the resulting Smith chart points may be joined by straight lines to create a locus.

A locus of points on a Smith chart covering a range of frequencies can be used to visually represent:

how capacitive or how inductive a load is across the frequency range

how difficult matching is likely to be at various frequencies

how well matched a particular component is.

The accuracy of the Smith chart is reduced for problems involving a large locus of impedances or admittances, although the scaling can be magnified for individual areas to accommodate these.