Capacitive rotary coupling

A signal is transferred without brushes between rotatable and non-rotatable components of a machine. An input signal is applied to one of the components. An axially symmetrical electromagnetic field is generated in response to the input signal. The electromagnetic field is detected by the other component and an output signal is generated in response to the detected electromagnetic field. A rotating transformer couples an information signal or power from an auxiliary generator to an external device for processing. The rotating transformer includes a rotor assembly and a stator assembly. The rotor assembly includes a pair of rotor plates. The stator assembly includes a pair of stator plates and a pair of dielectrics. A dielectric is mounted to a stator plate and mounted adjacent and spaced apart from a corresponding rotor plate to form a capacitor between the stator plate and the rotor plate. A voltage signal is applied across the rotor plates to induce a voltage across the stator plate to thereby generate an output voltage signal. The output voltage signal may have a phase and amplitude proportional to the phase and amplitude of the input voltage signal.