An apparatus and a method for compensating phase errors in a wireless BSS. % amphoteric or zwitter-ionic surfactants 0. The housing has an outside end with an outside end rim with at least one aperture there through. The housing is mechanically coupled to the rotor by anti-friction elements such that the rotor is free to rotate about its central axis relative to the housing, and such that radial displacement of the rotor due to main shaft deflections results in a like radial displacement of the housing.