Field emission structures comprising electric or magnetic field sources having magnitudes, polarities, and positions corresponding to a desired spatial force function where a spatial force is created based upon the relative alignment of the field emission structures The magnetic field sources may be arranged according to a code having a desired autocorrelation function. In particular, a high peak to sidelobe autocorrelation performance may be found desirable. Specific exemplary embodiments are described having non-parallel linear substructures. The non-parallel linear substructures may use the same or different codes and may have none, one, or more magnets in common. Other embodiments include substructures spaced according to a spacing code. Exemplary spacing codes include, but are not limited to Golomb ruler or Costas array. A polarity code may be applied across the substructures.