The energy of a system of 3D dipoles on a 2D orthorhombic lattice is invest
igated as a function of the rhombic angle. The possibility of the metastabl
e ferromagnetic state above the main antiferromagnetic state is shown. The
mechanisms of magnetization reversal are analyzed. Nonuniform structures wi
th the long range order of the ferromagnetic type (vortices and domain wall
s) on bounded lattices are considered. The conditions when the upper terms
of the long wave expansion of the Fourier images of the dipole sums plays a
significant role ape shown. (C) 1999 Elsevier Science B.V. All rights rese
rved.