We analyzed the structure of the magnetic field in active regions at coronal altitudes, determined using multiwavelength observations of polarized radio emission in the microwave range at the radiotelescope RATAN-600. The observations were compared with the current-free magnetic field extrapolation of the photospheric field. It is shown that the measured magnetic field is always larger than the reconstructed field at the same height. The slopes of the tubes obtained by this method corresponds to the slopes obtained for the reconstructed field, although the degree of the slope differ significantly. The measured magnetic field structure is probably more complicated than the structure obtained by the reconstruction. Comparison of our measurements with previous measurements of radio astronomical heights at fixed frequencies showed good match.