  We have performed simultaneous measurements of microwave
absorption/reflection and magneto-transport characteristics of a high mobility
two-dimensional electrons in GaAs/AlGaAs heterostructure in regime of
Microwave-Induced Resistance Oscillations (MIROs). It is shown that the
electrodynamic aspect of the problem is important in these experiments. In the
absorption experiments a broad cyclotron resonance line was observed due to a
large reflection from the highly conductive electron gas. There were no
additional features observed related to absorption at harmonics of the
cyclotron resonance. In near-field reflection experiments a very different
oscillation pattern was revealed when compared to MIROs. The oscillation
pattern observed in the reflection experiments is probably due to plasma
effects occurring in a finite-size sample. The whole microscopic picture of
MIROs is more complicated than simply a resonant absorption at harmonics of the
cyclotron resonance. Nevertheless, the experimental observations are in good
agreement with the model by Ryzhii et al. involving the photo-assisted
scattering in the presence of a crossed magnetic field and dc bias. The
observed damping factor of MIROs may be attributed to a change in the electron
mobility as a function of temperature.
