Features of the Spectra of Microwave Sources above Sunspots Inferred from Observations with RATAN-600

The flux density spectra of cyclotron sources above the sunspots were obtained by observations with RATAN-600 in the range of 1.7–10 cm with high spectral (\(\Delta f/f\sim 1{-}5\%\)) resolution and their spectral indices were estimated. The spectral index was then utilized to determine the magnitude of the magnetic field at the base of the transition region on the Sun. By analyzing the relationship between the emisson flux density of the sources and the magnetic field it was found that the observed characteristics of sunspot-associated sources did not align with predictions from a simplified radiation model commonly used for data interpretation. Specifically, there was an excess flux density in the spectrum of ordinary mode radiation compared to what was expected.