How does a smith chart work?

can any one explain to me hw and for wht a smitch chart is used to,

let assume i design an microstrip antenna and simulated it and the simulation gives a some values for simulated frequencies, so wht information i can obtain from the smitch chart and hw can i used it in impedence matching?

thanks
regards
danesh

The chart plots impedance in rectangular form with the curved lines and reflection coefficient in polar form with the radial and circumference scale. You can get two color charts in which the usually red scales are admittance.

From the location of a particular impedance on the chart you can graphically use lumped elements or transmission line segments to get the point to the center of the chart.

It is the graphical nature of the chart, which represents a very complex equation, which allows the user's imagination to be used to do the selection of the matching components.

Have a look at my tutorials on Smith Charts at:

http://www.odyseus.nildram.co.uk/RFM...ChartPart1.pdf

http://www.odyseus.nildram.co.uk/RFM...ChartPart2.pdf

http://www.odyseus.nildram.co.uk/RFM...ChartPart3.pdf

cheers

Ody

Dear odyseus

doesn't exist

Link is now fixed !

Try downloading now:

If you need a electronic tool, try CSMITH or ADLAB by Dr Stephen Webber

http://home.t-online.de/home/weberconnect/homepag2.htm

This is a very power tool, for a small price. You can always try out the full evaluation version (14 days).

He has a few good application notes on his homepage

Enjoy 8)

Hi danesh

now you can print the smith
or use excel smith

RGZ

hi danesh

The smith chart is a mapping from the impedance plane to the reflection coefficient plane that is if you know the impedance at any point in your circuit ( source, load etc.) you can know the corresponding reflection coefficient (magnitude, phase) from the smith chart by just reading from the chart! The centre of the smith chart generally represents 50 Ohm (75 Ohm is also possible)
There are 2 kinds (essentially the same !) of smith charts - Impedance & Admittance ones wherein you can plot either impedances or admittances as per the requirement ; The bottom (top) half of the circular Impedance chart (admittance chart) represents the Capacitive reactance (susceptance) & the top (bottom) half in the impedance (admittance) chart represents the inductive reactance (susceptance) region; the different circles (with centres lying on the same line) on the smith chart represent constant resistance points.

can any body give me a smith tool for matched circuit?

Hey,

There used to be an impedance matching program available from motorola. I am not sure if its available now also. Otherwise, you can visit www.circuitsage.com. There you will find a lot of shareware files for the same.