  We present deep L-Band observations of the equatorial field centered on the
z=6.3 SDSS QSO, reaching a 1 sigma sensitivity of ~2.5 uJy at the center of the
field. We extracted a catalog of 1489 radio sources down to a flux density of
~12.5 uJy (5 sigma) over a field of view of ~ 30' diameter. We derived the
source counts accounting for catalog reliability and completeness, and compared
them with others available in the literature. Our source counts are among the
deepest available so far, and, overall, are consistent with recent counts'
determinations and models. We detected for the first time in the radio band the
SDSS J1030+0524 QSO (26 +/- 5 uJy). We derived its optical radio loudness R_O =
0.62 +/- 0.12, which makes it the most radio quiet AGN at z >~ 6 discovered so
far and detected at radio wavelengths. We unveiled extended diffuse radio
emission associated with the lobes of a bright FRII radio galaxy located close
to the center of the J1030 field, which is likely to become the future BCG of a
protocluster at z=1.7. The lobes' complex morphology, coupled with the presence
of X-ray diffuse emission detected around the FRII galaxy lobes, may point
toward an interaction between the radio jets and the external medium. We also
investigated the relation between radio and X-ray luminosity for a sample of
243 X-ray-selected objects obtained from 500 ks Chandra observations of the
same field, and spanning a wide redshift range (0 ~< z ~< 3). Focused on
sources with a spectroscopic redshift and classification, we found that sources
hosted by ETG and AGN follow Log(L_R)/Log(L_X) linear correlations with slopes
of ~0.6 and ~0.8, respectively. This is interpreted as a likely signature of
different efficiency in the accretion process. Finally, we found that most of
these sources (>~87%) show a radio-to-X-ray radio loudness R_X < -3.5,
classifying these objects as radio quiet.
