  We investigated the upper critical magnetic field, $H_{c}$, of a
superconductor-ferromagnet (S/F) bilayer of Nb/Cu$_{41}$Ni$_{59}$ and a Nb film
(as reference). We obtained the dependence of $H_{c\perp}$ and $H_{c\parallel}$
(perpendicular and parallel to the film plane, respectively) on the
temperature, $T$, by measurements of the resistive transitions and the
dependence on the inclination angle, $\theta$, of the applied field to the film
plane, by non-resonant microwave absorption. Over a wide range, $H_{c\perp}$
and $H_{c\parallel}$ show the temperature dependence predicted by the
Ginzburg-Landau theory. At low temperatures and close to the critical
temperature deviations are observed. While $H_{c}(\theta)$ of the Nb film
follows the Tinkham prediction for thin superconducting films, the
Nb/Cu$_{41}$Ni$_{59}$-bilayer data exhibit deviations when $\theta$ approaches
zero. We attribute this finding to the additional anisotropy induced by the
quasi-one-dimensional Fulde-Ferrell-Larkin-Ovchinnikov (FFLO)-like state and
propose a new vortex structure in S/F bilayers, adopting the segmentation
approach from high-temperature superconductors.
