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Adopting the thermal free-free emission mechanism, the coronal andchromospheric magnetic fields are derived from the polarization and spectralobservations with the Nobeyama Radioheliograph at 1.76 cm. The solar activeregions (AR) located near the disk center observed on January 8, 2015 (AR12257) and December 4, 2016 (AR 12615) are used for the estimate of thechromospheric and coronal magnetic fields with the microwave radioobservations. We compare solar radio maps of active regions for both intensityand circularly polarized component with the optical maps from observations withthe Helioseismic and Magnetic Imager and the chromosphere and corona transitionregion images obtained with the Atmospheric Imaging Assembly instrument, onboard the Solar Dynamic Observatory. We notice from the comparison betweenradio maps of both AR that the circular polarization degree in the AR 12257 isabout 2 percent, but the AR 12615 has a higher existent value by 3 percent.Radio observations provide us for direct measurements of magnetic fields in thechromospheric and coronal layers. We estimate the coronal magnetic fields usingthe Atmospheric Imaging Assembly observations by adopting magnetic loops in thecorona over some patches with weak photospheric magnetic fields. The coronalmagnetic field derived from the Atmospheric Imaging Assembly data was from 90to 240 Gauss. We also study the coronal magnetic fields based on the structureof the extrapolated field, where the result of the magnetic fields was in therange from 35 to 145 Gauss, showing that the difference in the coronal magneticfields between both results is attributed to the assumption of the force-freeapproximation.

Estimating the coronal and chromospheric magnetic fields of solar active  regions as observed with the Nobeyama Radioheliograph Compared with the  Extrapolated Linear Force-Free Field