The invention described herein has particular utility in applications where electrical power is coupled from a stationary location to a moving location with a minimum of radio frequency and electromagnetic interference.  Such an environment is encountered in spacecraft containing extremely sensitive electronic components which are being fed power from an on-board source via a transformer. 
Known prior art apparatus for coupling electromagnetic energy across a moving boundary or interface consist of rotary transformers, close coupled antennas, and capacitive plates.  The disadvantages of known prior art transformer apparatus include the presence of an external air gap separating the two moving elements from which electrical energy leaks or is radiated away.  Additionally, rotary transformers are sensitive to translational and/or rotational motions and the lack of parallelism between opposing, although non-contacting, surfaces results in changes in the electromagnetic coupling between the elements.  Capacitive devices are subject to changes in their operational medium such as humidity and have a tendency to arc.  In addition, where mutual rotation between elements is required, sliding contacts are often used to couple energy from the moving member, particularly where a rotation of 360.degree.  is provided.