Aspects of the Scattering and Impedance Properties of Chaotic Microwave   Cavities
  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. 
Sameer Hemmady, Xing Zheng, Thomas M. Antonsen Jr., Edward Ott and   Steven M. Anlage