1. A method of motion capture comprising the steps of: providing an energy source ( 73 ); said energy source ( 73 ) disposed on a subject ( 12 ) at a location to be tracked; said subject ( 12 ) moving from position-to-position within a volume of space ( 16 ); emitting a signal ( 40 ) from said energy source ( 73 ); providing a plurality of widely-spaced receiving antennas ( 76, 78 ) disposed at edges of said volume of space ( 16 ); measuring a phase difference (&Dgr;&phgr; 1 ) of said signal ( 40 ) being received at each independent pair of said plurality of receiving antennas ( 76, 78 ) when said energy source ( 73 ) is at a first position ( 72 ); changing a physical position of said energy source ( 73 ) from a first position ( 72 ) to a second position ( 74 ); measuring a phase difference (&Dgr;&phgr; 2 ) of said signal ( 40 ) being received at each said independent pair of said plurality of receiving antennas ( 76, 78 ) when said energy source ( 73 ) is at a second position ( 74 ); and estimating a change in said physical position of said energy source ( 73 ) by comparing measured phase differences (&Dgr;&phgr; 1, &Dgr;&phgr; 2 ) of received said signal ( 40 ) at each said independent pair of said plurality of receiving antennas ( 76, 78 ).