  We consider the statistics of the impedance of a chaotic microwave cavity
coupled to a single port. We remove the non-universal effects of the coupling
from the experimental data using the radiation impedance obtained directly from
the experiments. We thus obtain the normalized impedance whose Probability
Density Function (PDF) is predicted to be universal in that it depends only on
the loss (quality factor) of the cavity. We find that impedance fluctuations
decrease with increasing loss. The results apply to scattering measurements on
any wave chaotic system.
