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We can make following observations about the constant VSWR circles: |
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All the circles have same center, the origin of the complex  -plane. |
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The origin in the  -plane represents  or  . As we move radially outwards the  and hence  increases monotonically and for the outermost (unity) circle,  and  . |
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The origin corresponds to the condition  , i.e., no reflection on the line. This point represents the best
matching of the load as there is no reflected power on the line. For the outer most circle  , and we get the
worst impedance matching as the entire power is reflected on the transmission line. We can therefore make
a
general statement that closer is the point to the origin of the  -plane, (i.e., the center of the Smith chart)
better is the impedance matching. |
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As we have defined earlier, the  indicates a distance towards the generator. As  becomes more positive,
 decreases and the point moves clockwise on the constant VSWR circle. If we move away from the generator,  becomes negative and then the point on the circle moves in the anticlockwise direction. |
