  We present a formulation of the quasiclassical theory of junctions between
itinerant antiferromagnets (AF) and s-wave (sSC) and d-wave superconductors
(dSC). For the simplest two-sublattice antiferromagnet on a bipartite lattice,
we derive Andreev-type equations and show that their solutions lead to a novel
channel of quasiparticle reflection. In particular, quasiparticles in a normal
metal with energies less than or comparable to the antiferromagnetic gap
experience spin-dependent retroreflection at antiferromagnet-normal metal
(AF/N) transparent (100) and (110) interfaces. A relative phase difference of
pi between up spin and down spin quasiparticle reflection amplitudes is shown
to lead to zero-energy interface bound states on AF/sSC interfaces. For an
sSC/AF/sSC junction, these bound states are found to be split, due to a finite
width of the AF interlayer, and carry the supercurrent. At AF/dSC interfaces we
find no zero-energy bound states for both interface orientations we considered,
in contrast with the case of (110) impenetrable surface of a dSC.
