  Observations of radio supernovae often exhibit characteristics not readily
accounted for by a homogeneous, spherically symmetric synchrotron model; e.g.,
flat-topped spectra/lightcurves. It is shown that many of these deviations from
the standard model can be attributed to an inhomogeneous source structure. It
is argued that the radio emission in Type Ib/c supernovae has a small volume
filling factor and comes from a narrow region associated with the forward
shock, while the radio emission region in SN 1993J (Type IIb) is determined by
the extent of the Rayleigh-Taylor instability emanating from the contact
discontinuity. Attention is also drawn to the similarities between radio
supernovae and the structural properties of supernova remnants.
