  An Ising antiferromagnet on a stacked triangular lattice in zero field is
studied by Monte Carlo simulations, focusing on the character of the
low-temperature phase and the effect of the relative strength of the exchange
interaction in the stacking direction {\alpha}. Our results support the
presence of the 3D Wannier phase, with the sublattice magnetization structure
(m, -m, 0) and power-law decaying m with the lattice size. The extent of this
low-temperature phase shrinks with decreasing {\alpha}, however, it appears
even at very low values if it is accessed from higher temperatures by
sufficiently slow cooling.
