  We have surveyed six distinct `empty fields' using the Australia Telescope
Compact Array in an ultra-compact configuration with the aim of imaging, with a
high brightness sensitivity, any arcmin-scale brightness-temperature
anisotropies in the background radio sky. The six well-separated regions were
observed at a frequency of 8.7 GHz and the survey regions were limited by the
ATCA primary beams which have a full width at half maximum of 6 arcmin at this
frequency; all fields were observed with a resolution of 2 arcmin and an rms
thermal noise of 24 microJy/beam. After subtracting foreground confusion
detected in higher resolution images of the fields, residual fluctuations in
Stokes I images are consistent with the expectations from thermal noise and
weaker (unidentified) foreground sources; the Stokes Q and U images are
consistent with expectations from thermal noise.
  Within the sensitivity of our observations, we have no reason to believe that
there are any Sunyaev-Zeldovich holes in the microwave sky surveyed. Assuming
Gaussian-form CMB anisotropy with a `flat' spectrum, we derive 95 per cent
confidence upper limits of Q_flat < 10--11 microK in polarized intensity and
Q_flat < 25 microK in total intensity. The ATCA filter function peaks at l=4700
and has half maximum values at l=3350 and 6050.
