  We consider an infinite network of globally-coupled phase oscillators in
which the natural frequencies of the oscillators are drawn from a symmetric
bimodal distribution. We demonstrate that macroscopic chaos can occur in this
system when the coupling strength varies periodically in time. We identify
period-doubling cascades to chaos, attractor crises, and horseshoe dynamics for
the macroscopic mean field. Based on recent work that clarified the bifurcation
structure of the static bimodal Kuramoto system, we qualitatively describe the
mechanism for the generation of such complicated behavior in the time varying
case.
