Estimate of 〈B_⊥〉 using synthetic intensity data at 45 and 408 MHz obtained with model A from one MHD simulation (Bellomi et al. 2020) already implemented in P21 to study diffuse Galactic synchrotron emission. The initial mean magnetic-field strength of the simulation is 4 µG. The value of 〈B_⊥〉 is estimated as in Fig. 4. Left panel: ratio between the estimated 〈B_⊥〉 and the true median value of the plane-of-the-sky magnetic-field strength per pixel, ${\tilde{B}}_{\perp }$, shown as a function of ${\tilde{B}}_{\perp }$ for the three integration axes. Right panel: for the green case shown in the left panel, given the injected j_e-shape of model A in the simulations, 〈B_⊥〉 is also estimated using presently existing models; i.e. Orlando (2018, in purple) and Padovani et al. (2018, in teal). In all panels the, levels show the (0.5, 1, 1.5, 2) σ equivalent contours of the corresponding density of points.