Results of the polsolve fit to the simulated VGOS observations. Left panels: correlation plots between the true source polarization quantities (fractional polarization and EVPA at the fiducial frequency, RM, and polarization spectral index) and the polsolve estimates. The dotted lines indicate the 1:1 correlation. Right panels: simulated D-term spectra as thick lines, resulting from a frequency-dependent phase offset between the linear polarizers of the antennas, and the values fitted by polsolve.