This reflection coefficient is defined as lying between the values 1 (total reflection) to 0 (no reflection). It is well-known that a specific reflection coefficient can be represented graphically as being on a circle of radius equal to magnitude of the reflection coefficient. There are complex mathematical relationships between the reflection coefficient, the standing wave ratio (SWR) and the normalised load impedance Z L/Z 0. Now, if this line is terminated by a load impedance of the same value, Z 0, then all the power is transferred into the load.Īny other load impedance will cause some power to be reflected back (the proportion is defined as the reflection coefficient) resulting in standing waves along the lines. Any such complex impedance can be visualized as a point on the Argand diagram.Īrgand Diagram for representing Complex Impedanceįurther, we have learnt that a RF transmission line has a characteristic impedance (Z 0) dependent on its physical cross-sectional construction.
#The complete smith chart pdf how to
Now, with PCs readily available, there is less motivation to self-learn how to use these tools, which do provide an insight and simple means of handling the calculations involved in transmission lines and components at radio frequencies.Īs Hams, we have all learnt that an electronic component can be represented as an impedance which is a combination of (pure) resistance and (inductive or capacitive) reactance. Unfortunately, engineering schools always fail to teach students how to make practical use of Smith Charts (or even slide rules). Smith, who developed and published it originally in 1939.
This is called the Smith Chart, after the mathematician, P. RF engineers have also a tool which assists in the understanding of transmission lines.
Prior to the arrival of the electronic calculator, generations of engineers, through practical usage of their “slide rules”, gained an inherent understanding of logarithms. What is a Smith Chart ? by Robin Hodgson 9H1ZZ
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