  As a pilot study for the first all-sky radio survey at short wavelengths, we
have observed 1216 sq. deg. of the southern sky at 18GHz (16mm) using a novel
wide-band (3.4GHz bandwidth) analogue correlator on one baseline of the
Australia Telescope Compact Array (ATCA). We scanned a region of sky between
declination -71 and -59 degrees with an rms noise level of 15mJy. Follow-up
radio imaging of candidate sources above a 4 sigma detection limit of 60mJy
resulted in 221 confirmed detections, for which we have measured accurate
positions and flux densities. For extragalactic sources, the survey is roughly
70% complete at a flux density of 126mJy and 95% complete above 300mJy. Almost
half the detected sources lie within a few degrees of the Galactic plane, but
there are 123 sources with |b|>5 degrees which can be assumed to be
extragalactic. The differential source counts for extragalactic sources in the
range 0.1Jy < S_{18GHz} < 3Jy are well fitted by a relation of the form
n(S)=57(S/{Jy})^{-2.2\pm0.2} [Jy^-1 sr^-1], in good agreement with the 15GHz
counts published by Taylor et al. (2001) and Waldram et al. (2003). Over 70% of
the extragalactic sources have a flat radio spectrum (\alpha_{0.843}^{18}>
-0.5, S_{\nu}\propto\nu^{\alpha}), and 29% have inverted radio spectra
(\alpha_{0.843}^{18}> 0). The optical identification rate is high: 51% of the
extragalactic sources are identified with stellar objects (candidate QSOs), 22%
with galaxies and only 27% with faint optical objects or blank fields.
