Abstract: A communications system in which a communications channel is defined at least in part by an electromagnetic wave having a carrier frequency and an electric field vector, the extremity or terminus of which traces a non-linear periodic path at a rotation frequency less than the carrier frequency and greater than zero from the perspective of an observer looking into the axis of propagation of the wave. The transmitter of the communications system launches a wave having such characteristics and modulated with information in a suitable manner. The receiver of the communications system is sensitive to the periodic path and rotation frequency. The combination of the periodic path and the carrier frequency provides selectivity that can be used to define multiple communications channels.