Source A2142A. Top, left: total intensity contours and polarization vectors at 3.6   cm (8465 MHz). Contour levels are drawn at:  − 0.06 0.06 0.15 0.5 and 3 mJy/beam. Top, right: total intensity contours and polarization vectors at 6   cm (4535 MHz). Contour levels are drawn at:  − 0.1 0.1 0.5 1 and 3 mJy/beam. The angular resolution is 3.0′′  ×  3.0′′. The lines give the orientation of the electric vector position angle (E-field) and are proportional in length to the fractional polarization (1′′  ≃  10%). Bottom: trend of the fractional polarization as a function of the observing frequencies, at different source locations. The depolarization DP has been calculated as the ratio of the fractional polarization between the two extreme frequencies.