An apparatus for communicating with a radiation therapy devicecomprises a first plurality of omnidirectional radio antennas 212, 214 mountedupon a rotor 202, and a second plurality of omnidirectional radio antennas216,218 positioned at respective fixed locations off the rotor. The firstplurality ofantennas 212, 214 may be substantially equally spaced around the axis ofrotation of the rotor 202. The first plurality of antennas 212, 214 and thesecond plurality of antennas 216, 218 are positioned so as to allow line-of-sightradio communication between at least one of the first plurality of antennasandat least one of the second plurality of antennas at all angles of rotation oftherotor 202.
