  We consider a perfectly homogeneous, isotropic and spatially flat universe
which undergoes a sudden phase transition producing topological defects. We
assume that these defects form a coherent network which scales like the
background density during the radiation and matter dominated eras, and describe
them in terms of a few free functions. We carefully model the loss of scaling
invariance during the transition from radiation to matter dominated era. We
choose a simple set for the free functions, compute the microwave background
temperature anisotropies generated by such a network, and compare our results
to previous calculations.
