The observations of the radio eclipse of the Sun on 31 May, 2003 at the Crimean Astrophysical Observatory with the stationary radiotelescope RT-22 over millimeter range of waves allowed us to find out that the radio brightness of corona at distances of 350 000 and 700000 km above the photosphere is identical with the accuracy ΔT_K = 11 K. A compact radio source with an angular size of 3.36" and brightness temperature T_b = 3.18⋅10⁶ K is detected on the solar disc. During the eclipse an area of an increased radio brightness occurs above the limb of the Moon. Its occurrence can be explained by refraction of radio waves in a plasma layer with a height from 12 to 20 km and a maximum electronic concentration of 10³ см^-3.