  The study of the nature of faint radio sources is of great importance since a
significant fraction of these objects is thought to be composed of actively
star-forming galaxies. Due to the increased sensitivity of radio telescopes, we
are now not only able to catalogue large numbers of these sources in the
sub-millijansky regime, but also to start the study of the nature of
increasingly fainter microjansky sources.
  This paper presents a new very deep 1.4 GHz radio survey made as a part of
the Phoenix Deep Survey, a project aimed to study the nature of the faintest
radio sources. With a limiting sensitivity of 45 microJy, this new survey has
allowed us to assemble a large number of sources with 1.4 GHz flux densities
below 100 microJy. The resulting source counts and the analysis of the optical
properties of the faintest radio sources are presented.
