First measure a circle feature. This measurement will display in the Cartesian coordinates. This is the default in Calypso.
If you were to add a true position characteristic it would look like this
In order to change this to a polar output you will need to change the format that Calypso reads this measured feature. Highlight the measured feature in the Feature list and click on the Resources menu. Now chose Feature Representation.
With the Circle highlighted
Click on the Mode pull down
Click on the CYL (Polar) radial button
Now the True Position will read in Polar coordinates