The present invention provides an apparatus for the communication of power or data signals across the rotating gap of two tubular members, such as the stator and rotor of a mud motor, and between said rotating members of a drill string through inductive couplers located axially along the drill strin...http://www.google.ca/patents/US7168510?utm_source=gb-gplus-sharePatent US7168510 - Electrical transmission apparatus through rotating tubular members
