  The momentum dependence of the antikaon optical potential in nuclear matter
is obtained from a microscopic and self-consistent calculation using the
meson-exchange J\"ulich $\bar{K}N$ interaction. Two self-consistent schemes are
discussed, which would lead to substantially different predictions for the
width of ${\bar K}$ nuclear bound states. The effect of higher partial waves of
the $\bar{K}N$ interaction, beyond the L=0 component, is studied and found to
have moderate but non-negligible effects on the ${\bar K}$ nuclear potential at
zero momentum. At momenta as large as 500 MeV/c, relevant in the analysis of
heavy-ion collisions, the higher partial partial waves modify the ${\bar K}$
optical potential by nearly a factor of two.
