The antenna is made by mounting all the elements from two identical antennę on a single boom, but in perpendicular planes, and delaying one of the two feed points by 90°. You change the CP direction by changing which set of elements get delayed, or you can use just one set. This requires either two downleads or one, but with a remotely controlled coaxial switch, at the antenna.
A friend lived 200 Km from a CP TV station he enjoyed viewing, but an offending horizontal station was another 150 Km in the same direction, and whenever it got cold, the distant station would cause objectionable QRM. Using a vertical antenna would not resolve the issue because extended propagation always randomizes polarity. He built two CP receiving antennę, one CW and one CCW and connected them out of phase. They both received the linear station and their combined output was next to zero, but only one of them received the target station. It seemed counterintuitive, but connecting and disconnecting the second antenna had no effect on the strength of the desired station, but connecting it make the offending station go away.