The Deep SWIRE Field II. 90cm Continuum Observations and 20cm-90cm
  Spectra
  We present one of the deepest radio continuum surveys to date at a wavelength
~1 meter, at 324.5 MHz. The data reduction and analysis are described and an
electronic catalog of the sources detected above 5 sigma is presented. We also
discuss the observed angular size distribution for the sample. Using our deeper
20cm survey of the same field, we calculate spectral indices for sources
detected in both surveys. The spectral indices for 90cm-selected sources,
defined as S ~nu^(-alpha}, shows a peak near 0.7 and only a few sources with
very steep spectra. Thus no large population of very steep spectrum microJy
sources seems to exist down to the limit of our survey.
  For 20cm-selected sources, we find similar mean spectral indices for sources
with S_20>1 mJy. For weaker sources, below the detection limit for individual
sources at 90cm, we use stacking to study the radio spectra. We find that the
spectral indices of small (<3") 20cm-selected sources with S_20< 10 mJy have
mean and median alpha(90,20)~0.3-0.5. This is flatter than the spectral indices
of the stronger source population.
  We report log N-log S counts at 90cm which show a flattening below 5 mJy.
Given the median redshift of the population, z~1, the spectral flattening and
the flattening of the log N-log S counts occurs at radio luminosities normally
associated with AGN rather than with galaxies dominated by star-formation.
