  We develop a theory of magneto-transport properties of two-dimensional
electron gas in cylindrical geometry where finite bias and microwave are
locally applied. By invesitgating the Landauer conductance based on Floquet
theory, we obtain the conductance without perturbation analysis. We show that
the dc conductance becomes negative when dc electric field is applied inside
the 2DEG with sufficient microwave power. A positive sign of the current is
restored by increasing dc bias. We analyze the radiation induced
non-equilibrium distribution function with respect to the frequency of the
applied microwave.
