  Fluctuations in the Galactic synchrotron emission can be traced by the
angular power spectrum of radio maps at low multipoles. At frequencies below
few GHz, large-scale anisotropies are mainly induced by magnetic field
turbulence. By performing an analysis of five radio maps, we extract
constraints on turbulence spectral index and halo scale. Results favour a power
spectrum significantly flatter than for 3D Kolmogorov-like turbulence, and a
thin halo. This can be interpreted as an indication supporting non-conventional
models of propagation of cosmic-ray particles in the Galaxy, or as a suggestion
of a spectral-index break in the observed magnetic turbulence power spectrum.
