  Strong ferromagnetic interlayer exchange couplings $J$ in perpendicularly
magnetized systems are becoming increasingly desirable for applications. We
study whether ferromagnetic interlayer exchange couplings can be measured by a
combination of broadband ferromagnetic resonance methods and magnetometry
hysteresis loops. For this we model the switching and the eigenexcitations in
bilayer systems comprising a soft layer coupled to a thicker harder layer that
possesses higher perpendicular magnetic anisotropy. For large $J >0$ the
switching fields are essentially independent of $J$ but the frequency of the
optical eigenmode of the bilayer and the linewidth of the acoustical and
optical eigenmode are directly sensitive to the coupling. We derive a corpus of
compact analytical expressions to analyze these frequencies, their linewidth
and discuss the meaning thereof. We illustrate this corpus on a system
mimicking the fixed layers of a magnetic tunnel junction meant for spin torque
applications.
