Scattering matrices with block symmetry, which correspond to a scattering process in cavities with geometrical symmetry, are analyzed. The distribution of the transmission coefficient is computed for a different number of channels in the case of a system with or without the time-reversal invariance. An interpolating formula for the case of gradual time reversal symmetry breaking is proposed.

• Received 23 December 1996

DOI:https://doi.org/10.1103/PhysRevE.56.2257