On the relation between spectral characteristics of the microwave emission from solar active regions and physical conditions of the solar atmosphere

Spectrographic observations of the microwave emission from selected active regions were analyzed and compared with S-component emission models. The observations were obtained by spectrographs of the NIRFI working in the ranges of 12-8 and 7-5 GHz covering the high-frequency part of the S-component spectrum. The measurements were carried out at the RT-22 radio telescope of the FIAN Radio Astronomy Station at Pushchino with an angular resolution of about 9 arc minutes. The conclusions obtained mainly relate to the reversal of the slope of the flux spectrum in the short cm-region by the change of the emission mechanism; to an excess of the observed flux spectrum at long cm-waves, which is probably due to hot loop structures; and to the interpretation of the proton-flare criterion of Tanaka and Kakinuma based on model calculations. (author)