  Following an idea by Joyner et al. [Europhys. Lett. 107, 50004 (2014)] a
microwave graph with an antiunitary symmetry T obeying T^2=-1 is realized. The
Kramers doublets expected for such systems are clearly identified and can be
lifted by a perturbation which breaks the antiunitary symmetry. The observed
spectral level spacings distribution of the Kramers doublets is in agreement
with the predictions from the Gaussian symplectic ensemble expected for chaotic
systems with such a symmetry.
