  From the measurement of a reflection spectrum of an open microwave cavity the
poles of the scattering matrix in the complex plane have been determined. The
resonances have been extracted by means of the harmonic inversion method. By
this it became possible to resolve the resonances in a regime where the line
widths exceed the mean level spacing up to a factor of 10, a value inaccessible
in experiments up to now. The obtained experimental distributions of line
widths were found to be in perfect agreement with predictions from random
matrix theory when wall absorption and fluctuations caused by couplings to
additional channels are considered.
