A full circle around the perimeter of the Smith Chart (360 degrees) corresponds to a half wavelength (i.e. 180 degrees, or PI radians) at your frequency of interest. Note the text "Wavelength toward generator/load" on the edge of the chart.
"RF Circuit Design" by Chris Bowick, SAMS Publishing, ISBN 0-672-21868-2 is a very good reference on the Smith Chart if it is still available.
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