US Patent 7459999 Variable-diameter electromagnetic coil

The present disclosure relates to a variable diameter electromagnetic coil. The coil may include a coil winding containing inner and outer winding layers. The coil may incorporate a first hub including one or a plurality of inner supports, one of the inner supports connected to a location on the inner winding layer. A second hub may then be provided including one or a plurality of outer supports, one of the outer supports connected to a location on the outer winding layer. One of the first or second hubs may be capable of rotating to cause the coil winding to wind or unwind. An interconnect hub may then be provided which may be capable of providing electrical connection to the coil winding.