  We complement a recent calculation (P.B. Gossiaux and the present authors,
Ann. Phys. (N.Y.) in press) of the autocorrelation function of the conductance
versus magnetic field strength for ballistic electron transport through
microstructures with the shape of a classically chaotic billiard coupled to
ideal leads. The function depends on the total number M of channels and the
parameter t which measures the difference in magnetic field strengths. We
determine the leading terms in an asymptotic expansion for large t at fixed M,
and for large M at fixed t/M. We compare our results and the ones obtained in
the previous paper with the squared Lorentzian suggested by semiclassical
theory.
