  Radio surveys with the Australia Telescope Compact Array have been carried
out at 1.4 and 2.4 GHz with a limiting flux of 0.2 mJy at each frequency in the
Marano Field, in which deep optical and X-ray (ROSAT) data are also available.
In this paper we present the two radio samples, complete at the 5 sigma local
level, consisting of 63 and 48 sources respectively at 1.4 and 2.4 GHz. The 1.4
GHz normalized differential source counts show a flattening below about one
mJy, in agreement with the results from previous surveys. The 2.4 GHz counts,
which are the deepest at this or similar frequencies (e.g. 2.7 GHz), agree well
with the 2.7 GHz counts at higher fluxes and with the extrapolations down to 2
mJy based on fluctuation analyses. The 2.4-1.4 GHz spectral index distributions
are presented for both the complete samples in two flux density intervals. The
median spectral index for the 1.4 GHz sample remains constant at about 0.8,
down to the lowest fluxes (S(1.4)=0.2 mJy), while for the higher frequency
sample the spectral index distribution flattens in the lower flux density
interval (S(2.4) < 0.8 mJy). A significant number of sources with inverted
spectrum (< 0) does appear in both samples, at low flux level (< 2 mJy). These
sources, which are about 25% of the complete sample at 2.4 GHz, are probably
the ``bright'' counterpart of the inverted spectrum sources which appear to be
almost 50% of the sources in the even deeper radio surveys (at about 20-40
microJy).
