  Cosmic-ray (CR) leptons produce radio synchrotron radiation by gyrating in
interstellar magnetic fields (B-field). Details of B-fields, CR electron
distributions and propagation are still uncertain. We present developments in
our modelling of Galactic radio emission with the GALPROP code. It now includes
calculations of radio polarization, absorption, and free-free emission. Total
and polarized synchrotron emission are investigated in the context of physical
model of CR propagation. Predictions are compared with radio data from 22 MHz
to 2.3 GHz, and Wilkinson Microwave Anisotropy Probe data at 23 GHz. Spatial
and spectral effects on the synchrotron modelling with different CR
distribution, propagation halo size and CR propagation models are presented. We
find that all-sky total intensity and polarization maps are reasonably
reproduced by including an anisotropic B-field, with comparable intensity to
the regular one defined by rotation measures. A halo size of 10 kpc, which is
larger than usually assumed, is favoured. This work provides a basis for
further studies on foreground emission with the Planck satellite and on
interstellar gamma-ray emission with Fermi-Large Area Telescope.
