  The results of an optical and infrared investigation of a complete sub-sample
of the Leiden-Berkeley Deep Survey (flux > 1 mJy at 1.4 GHz) are presented.
Optical counterparts have been identified for 69 of the 73 sources in the two
Hercules fields, and redshifts obtained for 49 of them. Photometric redshifts
are computed from the g,r,i,K data for the remaining 21 sources. This complete
sample is compared with the radio luminosity functions (RLFs) of Dunlop and
Peacock (1990). The RLF models successfully trace the evolution of the radio
sources with redshift, but there is some disagreement between the
luminosity-dependence of the models and the data. The observed RLF for the
lower luminosity population (log P < 26) shows evidence for a cut-off at lower
redshifts (z=0.5-1.5) than for the more powerful objects.
