  The conductance and the Fano factor in a graphene sheet in the ballistic
regime are calculated. The electrostatic potential in the sheet is modeled by a
trapezoid barrier, which allows to use the exact solution of the Dirac equation
in a uniform electric field in the slope areas (the two lateral sides of the
trapezoid). A special attention is devoted to asymmetry with respect to the
sign of the gate voltage, which is connected with the difference between the
Klein tunneling and the over-barrier reflection. The comparison of the
developed theory with the experiment supports the conclusion that the Klein
tunneling was revealed experimentally.
