Top panel: redshift distribution of our 7729 radio sources. Spectroscopic and photometric redshifts are shown in red and blue, respectively, while the black line is the sum of the two. The scale of the y axis is logarithmic. Bottom panel: circles show the rest-frame 3 GHz luminosity as a function of redshift, both spectroscopic (red) and photometric (blue). The horizontal bars indicates the average ±1σ uncertainty range of the photometric redshifts in the various redshift bins. The corresponding 1.4 GHz luminosity (scaled by using α = –0.7) is shown for comparison on the right y axis. The black solid line indicates the 5σ luminosity limit at 3 GHz.