Some spectra as example of the large variety of spectral behaviour in total intensity (squares) and polarization (diamonds) for a set of point sources. We selected examples of inverted, flat, peaked and steep total intensity behaviour similar (top panels) and different (bottom panels) to the polarization behaviour. The triangles correspond to the fraction of polarization. The low-frequency values refer to data from SUMSS (0.843 GHz) and NVSS (1.4 GHz) catalogues in total intensity (small squares) and, where available, polarization (small diamonds).