  A representation of partially spatially coherent and partially polarized
stationary electromagnetic fields is given in terms of mutually uncorrelated,
transversely shifted, fully coherent and polarized elementary electric-field
modes. This representation allows one to propagate non-paraxial partially
coherent vector fields using techniques for spatially fully coherent fields,
which are numerically far more efficient than methods for propagating
correlation functions. A procedure is given to determine the elementary modes
from the radiant intensity and the far-zone polarization properties of the
entire field. The method is applied to quasihomogeneous fields with
rotationally symmetric cosine-modulated radiant intensity distributions. This
is an adequate model for fields emitted by, e.g., many light-emitting diodes.
