  We present a systematic study of the microwave-induced oscillations in the
magnetoresistance of a 2D electron gas for mixed disorder including both
short-range and long-range components. The obtained photoconductivity tensor
contains contributions of four distinct transport mechanisms. We show that the
photoresponse depends crucially on the relative weight of the short-range
component of disorder. Depending on the properties of disorder, the theory
allows one to identify the temperature range within which the photoresponse is
dominated by one of the mechanisms analyzed in the paper.
